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N361: Pathophysiology II > Module 6 - Genetics > Flashcards

Module 6 - Genetics Flashcards

1
Q

Gene

A

section of a DNA molecule

has the biochemical instructions for cells

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2
Q

Genetic information, stored in the structure of DNA, determines what things?

A

Directs cell structure and day to day cell function

determines appearance

environment response

unit of inheritance

disease susceptibility

how we react to drugs/medications

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3
Q

Genome

A

total genetic content

Human genome has about 20,300 protein encoding genes

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4
Q

The genome is __% the same in all people

A

99.9%

the 0.1% difference accounts for individual trait differences

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5
Q

___ create much of our identity

A

Proteins

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6
Q

Genetic information survives through what 3 things?

A
  1. Cell division
  2. Cell Renewal
  3. Tissue growth
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7
Q

DNA can ___

A

replicate

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8
Q

DNA converts to mRNA via ___

A

transcription

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9
Q

RNA makes proteins via ___

A

translation

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10
Q

What is the structure of Deoxyribonucleic Acid (DNA)?

A

Large stable macromolecule

Double helix and base pairing

“spiral staircase with the paired bases resembling steps”

It is a long double stranded helical molecule composed of nucleotides

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11
Q

Where is DNA primarily found?

A

Mostly in the nucleus but mtDNA is found in the mitochondria

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12
Q

What makes up a Nucleotide in DNA

A

Phosphoric Acid + 5 Carbon Sugar Deoxyribose _ 1 of 4 nitrogenous bases

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13
Q

2 Kinds of Nitrogenous Bases

A

Purines and Pyrimidines

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14
Q

Purines

A

2 nitrogen ring structures

  1. Adenine
  2. Guanine
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15
Q

Pyrimidines

A

Have one nitrogen ring

  1. Thymine (and Uracil)
  2. Cytosine
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16
Q

What are the complementary base pairs in DNA and RNA?

A

A-T (DNA only)

A-U (RNA only)

G-C

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17
Q

Nucleotide

A

single building block of DNA

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18
Q

Nitrogenous Bases

A

The basic structure of DNA and carry genetic information in 2 groups (purines and pyrimidines)

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19
Q

How many strands are there after DNA replication?

A

2 strands become 4 strands

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20
Q

What is the backbone of DNA?

A

alternating groups of sugars and phosphate with paired nitrogenous bases projecting inwards from the sides of sugar molecules

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21
Q

mtDNA

A

mitochondrial DNA

Mitochondria have their own DNA, different from that of the nucleus

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22
Q

What is the structure of mtDNA

A

packaged in a double stranded CIRCULAR chromosome

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23
Q

How is mtDNA passed on?

A

from mother to children

*so all mtDNA disorders come from the mother, not the father

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24
Q

What does mtDNA code for and why?

A

Codes for enzymes involved in oxidative phosphorylation reactions

without it/if mutated oxi phos cannot occur leading to energy and ATP abnormalities

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25
Q

Which kind of DNA can repair itself and which cannot?

A

DNA - can

mtDNA cannot repair itself

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26
Q

Mutations of mtDNA tend to cause dysfunction in what?

A

tissues with high utilization of ATP (ex: nerve, kidney, muscle, liver)

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27
Q

What is linked to aging?

A

mtDNA

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28
Q

What mutates more rapidly, DNA or mtDNA

A

mtDNA

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29
Q

What kind of genetic information is more likely to remain after extensive damage due to the sheer amount of copies there are?

A

mtDNA

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30
Q

Chromosomes

A

visible only ion dividing cells

they are tightly packaged DNA

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31
Q

Chromosomes take shape…

A

before division

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32
Q

Centromere

A

Connects the sides of chromosomes and are found in the pinched region of the chromosome

made of DNA and proteins

it connects the chromosome

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33
Q

Chromatin

A

DNA molecules and structural proteins combined

Seen in non-dividing cells

It is unwound DNA and proteins together - DNA does its work in this less compacted form

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34
Q

Histones

A

Proteins that the double helix wraps around (histones = proteins) when DNA replicates for organization

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35
Q

What form does DNA take during division?

A

Chromosome

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36
Q

What form does DNA take when not dividing?

A

Chromatin

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37
Q

The genome is distributed in ___

A

chromosomes (it is through chromosomes that our genetic information is distributed)

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38
Q

Genes are linear along ___

A

chromosomes

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39
Q

Humans have __ chromosomes arranged in pairs

A

46

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40
Q

Each chromosome contains..

A

1 continuous linear DNA helix

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41
Q

Haploid

A

A complete set of one of each chromosomes (23 total)

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42
Q

Diploid

A

A cell containing 2 sets of the 23 chromosomes in pairs (46 total)

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43
Q

Autosomes

A

22 chromosome pairs that do not determine gender

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44
Q

Sex Chromosomes

A

X and Y chromosomes

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45
Q

Female Sex Chromosomes

A

XX

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46
Q

Male Sex Chromosomes

A

XY

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47
Q

Reproductive Cells

A

Ova and Sperm (each only have 1 chromosome from each parent making them haploid (23) cells)

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48
Q

DNA is the basis of life because of 3 qualities what are they?

A
  1. they hold information
  2. It can copy itself
  3. it changes
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49
Q

In a female, only what is active in controlling the expression of genetic traits?

A

one X chromosome

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50
Q

Karyotype

A

an organized arrangement of all the chromosomes within one cell during the M phase of mitosis

Paired and then arranged by number according to size and position of the centromere

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51
Q

What model did Watson and Crick (1953) suggest was the proper model of DNA replication?

A

Semiconservative model

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52
Q

Meselson-Stahl Experiment

A

experiment that verified the semiconservative model of DNA replication

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53
Q

Semiconservative Model of DNA replication

A

Describes the method by which DNA is replicated in all known cells

It states that replication has DNA replicate before cell division to make two copies each containing one of the original DNA strands and an entirely new copy strand

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54
Q

RNA

A

long single stranded molecule involved in the actual synthesis of cellular enzymes and proteins

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55
Q

RNA polymerase

A

enzyme in the nucleus that synthesizes RNA

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56
Q

What is the structure of RNA

A

single nucleotide chain and one complimentary copy of a DNA strand

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57
Q

What is different between RNA and DNA?

A
  1. RNA is single stranded but DNA is double helix
  2. Thymine is replaced with Uracil in RNA
  3. RNA has a RIBOSE instead of Deoxyribose sugar
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58
Q

RNA can act …

A

as an enzyme and speed up chemical reactions

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59
Q

RNA is a ___ copy of a DNA strand

A

complementary copy

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60
Q

3 Types of RNA

A

mRNA

tRNA

rRNA

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61
Q

mRNA

A

Messenger RNA - “The Template”

Contains the transcribed instructions for protein synthesis obtained from the DNA molecule and carrier them to the cytoplasm while leaving the nucleolus

Holds the information on the order of amino acids in a protein via Codon sequences of nucleotides

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62
Q

Codon

A

chain of 3 mRNA nucleotides that specify insertion of one of the twenty different amino acids

A sequence of 3 bases forming a fundamental triplet code for transmitting information for protein synthesis

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63
Q

tRNA

A

Transfer RNA - “The Transporter”

Delivers the appropriate amino acids to the ribosome, where they are incorporated into the protein being synthesized

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64
Q

What is unique about tRNA shape?

A

There are 20 different kinds, each corresponding to one of 20 amino acids, in order to bring the AA to the ribosomes

Also it is a cloverleaf shape and the smallest RNA

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65
Q

What is the smallest RNA type

A

tRNA

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66
Q

Where is the site of protein synthesis

A

Ribosomes

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67
Q

rRNA

A

Ribosomal RNA - “The Synthesizer”

Provides the machinery needed for protein synthesis

It provides the structural support for the growing protein

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68
Q

Where is rRNA synthesized?

A

in the nucleolus (unlike other RNA types) and transported to the endoplasmic reticulum

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69
Q

Function and Structure of mRNA

A

functions as a blueprint; it is a code for a single protein (or polypeptide chain)

it is single stranded

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70
Q

Structure and Function of tRNA

A

the translator, capable of reading the mRNA language and binding corresponding amino acid to a growing peptide chain

cloverleaf shape

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71
Q

Structure and Function of rRNA

A

the factory, an “enzyme” of sorts

it is a complex with proteins

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72
Q

The bridge between the gene and protein is?

A

RNA

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73
Q

Transcription

A

the process of making RNA from DNA

RNA copy of a DNA sequence

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74
Q

Translation

A

the process of making proteins from RNA (genetic code to protein code)

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75
Q

In eukaryotes, RNA must undergo what to become mRNA

A

processing

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76
Q

Protein Synthesis

A

the selective activation of a gene which results in the production of the appropriate protein

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77
Q

What things are required to meet in translation for protein synthesis?

A

mature mRNA

tRNA

molecules carrying AA

rRNA

ATP and GTP

Verious protein factors

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78
Q

Where does transcription occur?

A

cell nucleolus

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79
Q

How is transcription done?

A

Weak H bonds of DNA are broken so free RNA nucleotides can pair with exposed DNA counterparts (unzipping) on the meaningful DNA strand –> RNA polymerase recognized the beginning or start sequence of a gene –> RNA polymerase then attaches to the double stranded DNA and copies the meaningful strand into a single strand of RNA –> once at the stop signal, the enzyme leaves the gene and releases the RNA strand

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80
Q

The Genetic Code

A

universal language used by most living cells

Four (nitrogenous) bases make up the alphabet for this code and can be arranged in 64 possible combinations of 3s called codons

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81
Q

Each gene provides the genetic code for making…

A

one specific protein

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82
Q

61 codon combinations correspond to a specific AA, but 3 are…

A

stop codons

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83
Q

How many amino acids are used in protein synthesis?

A

only 20, so the code is redundant or degenerate

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84
Q

Synonyms

A

codons that specify the same amino acids

they usually have the first two bases the same, but the third base differs

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85
Q

Stop Code/Coedon

A

signals the end of a protein molecule

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86
Q

Amino acids are the …

A

building blocks of life (and proteins)

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87
Q

the genetic code can survive…

A

the many stages of cell division, cell renewal, and tissue growth

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88
Q

Translation

A

process of matching amino acieds to corresponding sets of 3 bases (codons) and linking them into a protein

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89
Q

How does translation occur?

A

RNA leaves the nucleus and attaches to the (small rRNA subunit) ribosome to begin (it contains the instructions for a particular protein) –> AAs are brought by tRNA and linked to make polypeptide chains –> Ribosomes read the 3 bases together to do the corresponding bases

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90
Q

If the mRNA codon is UCG, what will the tRNA bring to link?

A

AGC (complementary/pair to it)

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91
Q

What is the pathway to DNA directed protein synthesis?

A

DNA (nucleus) –> mRNA (Nucleus) –> tRNA (cytoplasm) –> rRNA (ribosome in cytoplasm) –> protein synthesis

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92
Q

The basic structure of a protein is …

A

an amino acid sequence

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93
Q

What are proteins responsible for?

A

The functional diversity of cells

Performs most biological functions

Has many regulatory processes take place

Can cause many disease processes to occur

Where most drug targets are found (here and at translation)

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94
Q

What determines a proteins function?

A

the AA sequence/chain

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95
Q

Example of a protein that does regulatory processes?

A

Dystrophin - structural protein - it functions to maintain muscle integrity, and a mutation in the gene coding for this protein can lead to the most commonly inherited myopathy, Duchenne Muscular Dystrophy

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96
Q

Cell Proliferation

A

process by which cells divide and reproduce

inherent adaptive mechanism for replacing body cells when old cells die or additional cells are needed

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97
Q

__% of body cells are replaced daily either via mitosis or meiosis

A

10%

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98
Q

2 Kinds of Cell Division

A

Mitosis

Meiosis

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99
Q

Gametes

A

ovum and sperm

haploid (1 set of chromosomes)

designed for sexual function

one kind of cell

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100
Q

Somatic cells

A

any body cell diploid (2 chromosome sets) and not gametes

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101
Q

How many kinds of cells are there

A

200+

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102
Q

What are the 3 main types of cells

A
  1. Well differentiated that are unable to divide or reproduce
  2. Parent (progenitor) cells that continue to divide and reproduce
  3. Undifferentiated stem cells that can be triggered to enter the cell cycle and produce large numbers of progenitor cells when needed
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103
Q

Cell differentiation

A

process in which proliferating cells are transformed into different and more specialized cell types

process occurs in orderly steps

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104
Q

What does cell differentiation result in ?

A

Fully differentiated adult cell with specific sets of structural, functional, and life expectancy characteristics

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105
Q

What is the exchange existing with cell differentiation?

A

Increased specialization is exchanged for loss of ability to develop different cell characteristics and different cell lines

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106
Q

Stem cell

A

Cell that remains incompletely differentiated throughout life

remains quiescent until cell replenishment is needed

one daughter cell retains characteristics of a stem cell while the other differentiated into a parent or progenitor cell with a limited potential for differentiation and proliferation

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107
Q

Fully differentiated cells can no longer…

A

undergo mitosis

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108
Q

The ultimate stem cell is

A

a fertilized ovum

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109
Q

Cell Cycle

A

interval between each cell division

steps of cell division

110
Q

Phases of the Cell cycle

A

G1 (Gap 1) Phase –> S Phase –> G2 (Gap 2) Phase –> M Phase –> loops or G0 Phase

111
Q

G1 Phase

A

first phase of mitosis

cell resumes synthesis of RNA, proteins, and carbohydrates are synthesized but DNA synthesis ceases

This is the “Post mitotic phase”

The most variable in duration

112
Q

S Phase

A

10-20 hours long

DNA Synthesis occurs; gives rise to 2 separate sets of chromosomes (one for each daughter cell)

113
Q

G2 Phase

A

2-10 hours long

Premitotic phase where DNA synthesis ceases; RNA and protein synthesis continue though

114
Q

M Phase

A

Mitosis Phase taking 0.5 to 1 hour

Phase of cellular division or mitosis

115
Q

G0 Phase

A

Variable in length

Resting phase - phase in which cells are not actively dividing and are quiescent

116
Q

What is the length of the cell cycle?

A

Can be anywhere from < 8 hours to > 1 year

117
Q

The cell cycle phase longest in duration

A

G1 Phase

118
Q

The cell cycle phase where chromosomes become dense enough to be visible and when Karyotyping can be prepared?

A

M Phase

119
Q

Mitosis

A

Cell division of somatic cells

Asexual division

Occurs in M Phase

Involves DNA replication

Each daughter cell contains the same number of chromosomes as the parent cell

The 2 resulting daughter cells have identical sets of 23 chromosomes

120
Q

Stages of Mitosis

A

“Interphase” –> Prophase –> Prometaphase –> Metaphase –> Anaphase –> Telophase –> 2 Diploid Cells

PPMAT !

121
Q

Prophase

A

first stage of mitosis where the nuclear membrane breaks down and chromatin in the nucleus condenses into chromosomes

122
Q

Prometaphase

A

second stage of mitosis where there is no longer a recognizable nucleus

Mitotic spindles elongate to specific areas on chromosomes

123
Q

Metaphase

A

third stage of mitosis where tension is applied to spindle fibers which align chromosomes in one plane at the center of the cell

124
Q

Anaphase

A

fourth stage of mitosis where chromosomes are pulled away from the central plane toward the cell poles

125
Q

Telophase

A

fifth stage of mitosis where chromosomes arrive at cell poles and decondense

nuclear envelope re-forms around clusters at each end of the cell

126
Q

Meiosis

A

cell division which occurs only in reproductive cells during the formation of gametes (sex cells)

127
Q

How does DNA duplication differ in Meiosis compared to Mitosis?

A

A cell dividing by meiosis duplicates its DNA as with cells undergoing mitosis, BUT splits into 4 new cells instead of two and each contains only one copy of each chromosome - making them haploid

128
Q

What is the benefit of meiosis?

A

Maintains the chromosome number while mixing gene combinations through crossover

129
Q

Gametes form which cells?

A

Germ Line Cells

130
Q

Crossing Over

A

a biological occurrence when paired chromosomes of the same type line up and recombine the genes

this process allows parental relation while still having the offspring have different copies from the parents and unique individual characteristics

131
Q

Meiosis makes __ cells

A

4

132
Q

Mitosis makes __ cells

A

2

133
Q

Meiosis cells have ___ chromosomes

A

23 chromosomes

134
Q

Mitosis cells have ___ chromosomes

A

46 chromosomes

135
Q

Phases of Meiosis?

A

Interphase –> Meiosis 1 (PPMAT I) –> Meiosis 2 (PPMAT II) –> 4 Haploid Cells

136
Q

Meiosis v Mitosis: DNA Synthesis

A

Meiosis - occurs in S phase of interphase

Mitosis: Occurs in S phase of interphase

137
Q

Meiosis v Mitosis: Synapsis of Homologous Chromosomes

A

Meiosis - During prophase I

Mitosis - Does no occur in mitosis

138
Q

Meiosis v Mitosis: Crossover

A

Meiosis: During prophase 1

Mitosis: Does not occur

139
Q

Meiosis v Mitosis: Homologous Chromosomes line up at metaphase plate?

A

Meiosis: During metaphase I

Mitosis: does not occur in mitosis

140
Q

Meiosis v Mitosis: Sister Chromatids Line Up At Metaphase Plate

A

Meiosis: During metaphase II

Mitosis: during metaphase

141
Q

Meiosis v Mitosis: Outcome

A

Meiosis: 4 haploid cells at the end of meiosis II

Mitosis: 2 diploid cells at the end of mitosis

142
Q

Interphase

A

phase when DNA replicates before cell division starts

143
Q

2 Specialized forms of Meiosis

A

Oogenesis

Spermatogenesis

144
Q

Oogenesis

A

Female sex cell meiosis to produce an ovum

145
Q

Steps of Oogenesis

A

Meiosis I leads to a Secondary Oocyte and a Polar body –> Secondary Oocyte undergoes Meiosis 2 into an Ovum (mature oocyte) and a polar body, and the other polar body splits into 2 polar bodies

146
Q

Result of Oogenesis

A

1 Mature Ovum

3 Polar Bodies

147
Q

Polar Bodies

A

byproducts of oogenesis with no real biological role

148
Q

Spermatogenesis

A

Male sex cell meiosis to produce 4 sperm

149
Q

Steps of Spermatogenesis

A

Spermatogonium –Mitosis–> Meiosis I occurs leading to 2 secondary spermatocytes –> Meiosis 2 occurs leading to 4 viable daughter spermatids –> the 4 spermatids differentiate into sperm cells

150
Q

What would happen if we did not have meiosis?

A

Sperm and Ovum would each get 46 chromosomes leading to a fusion of 92 chromosomes total

151
Q

Human genome Project

A

1990-2003

Successful mapping of all genes in the human genome

152
Q

Genome Mapping

A

project that shows the relative location of 2 genetic traits and often leads to the specific location of a gene locus

153
Q

2 types of genomic maps?

A
  1. Genetic Maps
  2. Physical Maps
154
Q

Linkage Studies

A

assume genes occur in a linear pattern in chromosomes, and identify inherited traits that occur at a greater rate together than they would be by chance alone

155
Q

Linkage Analysis

A

can be used to clinically ID individuals in a family with a known genetic defect

156
Q

Genetic Maps

A

use linkage studies to estimate distance between chromosomal landmarks

157
Q

Physical Maps

A

measure the actual distance between chromosomal elements in biochemical units

158
Q

How is hybridization studies used to visualize and map genetic material in a cell?

A

Isolation can be achieved by fusing the cell with a mouse/rat cell to make a hybrid cell

This hybrid cell can then be used to understand genetic mutations and chromosomal abnormalities

159
Q

Hybridization studies are commonly used to study…

A

viruses and mutations involving cancer

160
Q

Genotype

A

genetic information stored in base pairs

161
Q

Phenotype

A

recognizable traits, physical or biochemical associated with a specific genotype

162
Q

Homozygotes

A

persons in whom the two alleles of a given pair are the same (AA or aa)

163
Q

Heterozygotes

A

persons having different alleles (Aa) at a gene locus

164
Q

Recessive Trait

A

expressed only as a homozygous pairing (aa)

165
Q

Dominant Trait

A

expressed either as homozygous (AA) or heterozygous (Aa)

166
Q

Single Gene Trait

A

when only one pair of genes is involved in the transmission of information

follows mendelian laws of inheritance

167
Q

Polygenic Inheritance

A

involves multiple genes at different loci with each gene adding a small additive effect in determining a trait

Predictable but with less reliability than single gene traits

168
Q

Multifactorial Inheritance

A

similar to polygenic inheritance but also includes environmental effects on genes

169
Q

Punnett Square

A

Shows potential genotypes and single gene inheritance expression for offspring of parents with TWO KNOWN GENOTYPES

170
Q

Mendelian Genetics

A

refers to the rules of inheritance of a SINGLE GENE TRAIT (one where expression is determined by inputs of 2 alleles, one from each parent)

Does not apply to traits needing more than 1 gene (like polygenic)

171
Q

Dominant Inheritance

A

required only one altered copy of a gene to result in gene expression

The child can have the trait as long as one parent has the trait

ex: Autosomal Dom - Huntington’s Coria Disease

172
Q

Recessive Inheritance

A

inheritance requires two altered copies of a gene, one from each parent, to result in gene expression

ex: Autosomal Rec - Cystic Fibrosis

173
Q

X Link Inheritance

A

Inheritance is associated with genes located on the X chromosome

174
Q

How does X linked inheritance differ between men and women?

A

Men are hemizygous (XY) so a mutation on the X chromosome results in gene expression, but women need mutation/change in both X chromosomes to show full expression usually

Hemizygous usually related to mother passing the affected X chromosome to the son

175
Q

Hemizygous

A

person with only one member of a chromosome pair or segment rather than the usual two

ex: XY in men

176
Q

Autosomal Dominant Inheritance

A

Single Gene Trait

Controlling gene trait on an autosomal chromosome expresses regardless of homo or hetero zygosity

177
Q

What kind of inheritance has carriers?

A

Recessive Inheritance

178
Q

Risk for passing on dominant inheritance in a heterozygous, dominant homozygous, and recessive homozygous individuals?

A

50% for Aa

100% for AA

0% for aa

179
Q

How does Dominant transmission stop?

A

when a generation arises where no family members are affected (have A)

180
Q

Males and Females transmit Dominant traits…

A

with equal frequency

Males and female can be affected and transmission of male-male is possible

181
Q

Does dominant traits skip generations?

A

no, successive generations are affected with no generations skipped

182
Q

Autosomal recessive Inheritance

A

Single Gene trait

only expressed when homozygous for the recessive allele

male and females are affected and can transmit the trait

183
Q

Do recessive traits skip generations?

A

They can because of carriers

usually then occurs in siblings rather than the parents

184
Q

How many carriers do you need to pass on a recessive trait?

A
  1. just one creates a carrier potentially
185
Q

If two parents are Aa, what are the chance of trait outcomes for the kids

A

AA - 25%

Aa (carriers) - 50%

aa (Affected with recessive -25%

186
Q

How many X chromosome copies are needed for X linked inheritance in males?

A

only 1 (need 2 in girls)

187
Q

How does affliction differ between males and females with x linked inherited disorders?

A

Females are affected less frequently and less severity if any, but can pass it on to their children

188
Q

Why can men only pass their affliction onto their daughters and not their sons?

A

Because men contribute the Y chromosome to boys so they cannot move the X affliction on (but the mother still could if she is a carrier)

189
Q

Example of an X linked recessive trait?

A

Red Green color blindness

Parents: X^BY and X^BX^b (25% normal male, 25% normal female, 25% female carrier, 25% color blind male)

190
Q

Mutations

A

accidental errors in duplication of DNA

can occur in somatic or germ cells

usually acquired but may be inherited

191
Q

What is the only way mutations can be inherited?

A

if the DNA is changed in the germ cell and passes on

192
Q

Causes, Spontaneous or Environmental, for Mutations

A

substitution of one base pair for another

the loss or addition of one or more base pairs

rearrangement of base pairs

environmental agents

chemicals

radiation (80% of which is environmental)

193
Q

Mutations can affect…

A

any part of the genome - transcription, proteins, translation, etc

194
Q

How do the impacts of mutations vary?

A

No effect

Beneficial effect

Impairment

195
Q

What sort of things can a harmful mutation cause?

A

Slow down protein synthesis

Impair protein function

Over Synthesize Proteins

196
Q

Causes for Birth Defects

A
  1. Genetic Factors
  2. Environmental Factors (Fetal Development)
  3. Intrauterine Factors (rare)
197
Q

Examples of Genetic Factors for Birth Defects?

A

single gene or multi factorial inheritance or chromosomal aberrations

198
Q

Examples of Environmental Factors for Birth Defects?

A

maternal disease

infections

drugs taken during pregnancy

199
Q

Examples of intrauterine Factors for Birth Defects?

A

fetal crowding

positioning

entanglement of fetal parts with the amnion

200
Q

Characteristics of Single Gene Disorders

A

Caused by a single defective or mutant allele at a single gene locus

May be present on an autosome or X chromosome

May affect one member or both members of an autosomal pair

Defects follow the Mendelian patterns of inheritance

Characterized by their patterns of transmission which are obtained thru a family genetic history

201
Q

How many generations need to be assessed for an accurate genetic family history?

A

3 generations

202
Q

Autosomal Dominant Disorder

A

a single mutant allele from an affected parent is transmitted to an offspring regardless of sex

203
Q

Autosomal Recessive Disorder

A

manifested only when both members of the gene pair are affected (both parents unaffected, but are carriers)

204
Q

X Linked Recessive Disorders

A

Always associated with the X chromosome

inheritance pattern is predominantly recessive

Women need both X to be affected in this case

205
Q

X Linked Dominant Disorders

A

conditions are expressed in both males and females, but are more severe in males

Mutant X supersedes other X for women in this case and causes the issue

You either have the mutant or not, if you do not then you cannot pass a mutant on unlike recessive

206
Q

Examples of Autosomal Dominant Disorders

A

Marfan’s Syndrome

Neurofibromatosis (NF)

207
Q

Marfan’s Syndrome

A

Autosomal dom Disorder

a connective tissue disorder manifested by changes in the skeleton, eyes, and cardiovascular system

Abnormality effects fibrillin 1 (coded for by FBN 1 gene)

No cure and diagnosis has major and minor criteria

Treatment is just regular system assessments for those at risk since it affects several organ systems

208
Q

Neurofibromatosis (NF)

A

Autosomal dom disorder

Condition involving neurogenic tumors that arise from Schwann cells and other elements of the peripheral nervous system

Children with this are susceptible for neuro complications including increased incidence of learning disabilities, ADD, speech anomalies, and complex partial tonic clonic seizures

209
Q

Examples of Autosomal recessive Disorders

A

Phenylketonuria (PKU)

Tay-Sachs Disease

210
Q

Phenylketonuria (PKU)

A

Autosomal Rec Disorder

A rare metabolic disorder caused by a deficiency of the liver enzyme phenylalanine hydroxylase

Insidious onset and difficult to assess

Need a special diet

If untreated there will be impaired speech, intellectual inability, and other neurodevelopmental impairments

Testing for PKU is mandatory and occurs 24-48 hours post-birth

211
Q

Tay-Sachs Disease

A

Auto Rec Disorder

A variant of a class of lysosomal storage diseases known as GANGLIOSIDOSE

Ganglioside in the membranes of nervous tissue are deposited in the neurons of the CNS and retina because of a failure of lysosomal degradation

Failure to break down GM2 ganglioside of a cell membrane leads to this

Infants appear normal at birth, but by 6-10 months there is decreased responsiveness, progressive weakness, muscle flaccidity, and death by age 4-5

This one highlights the important of family genetic history

212
Q

Examples of X Linked Recessive Disorders

A

Red green color blindness

Hemophilia A

213
Q

red green color blindness

A

X linked Rec Disorder

a person cannot distinguish between shades of red and green

So, on the X chromosome a gene for red sensitive opsin is need one or several green opsin so the sequences are similar and overlap leading to a crossover error

visual acuity is normal

more in males than females

214
Q

Hemophilia A

A

X Linked Rec Disorder

Blood cannot clot properly due to a deficiency in factor VIII

Abnormally heavy bleeding even from a small cut, easy bruising, and potential internal bleeding into the muscles and joints can occur

Accounts for most cases (1 in 4500) while Hemophilia B is 1in 20,000 live male births

215
Q

1/3 cases of hemophilia A are believed to be…

A

new mutations in the family rather than inherited from the mother

216
Q

What may be used to check for hemophilia A pre-birth?

A

Perinatal testing checking for bleeding from the umbilical cord

217
Q

How may women carriers differ in Hemophilia A presentation than men?

A

The carriers may show some mild signs of Factor VIII deficiency like easy bruising or taking longer to stop bleeding, but not all women show s/s just because they are carriers

218
Q

Fragile X Syndrome

A

X Linked Disorder associated with a fragile site on the X chromosome where the chromatin fails to condense during mitosis

Affects more men than females (1 in 4000 rather than 1 in 6000) - but nearly 4x the amount of women are carriers

causes intellectual disability

in all ethnic groups and races

219
Q

What is the second most common cause of Intellectual disability?

A

fragile x syndrome

220
Q

FMR-1

A

Fragile site of the X chromosome

Fragile x syndrome is characterized when many CGC repeats occur here

mutations here are unusual compared to other genes

221
Q

Nearly everyone with Fragile X syndrome have what?

A

instability in the gene leading to increased numbers of a portion of a gene in the CGC repeat region (50-200 CGC repeats)

222
Q

Premutations

A

A mutation where the person does not have the disorder but are at risk for passing it on to children or grandchildren as well as a risk for adult onset disorders

223
Q

What is the premutation in Fragile X syndrome

A

A CGC triplet repeat of 50-200 times

224
Q

What adult onset disorder are Male carriers with the fragile X/CGC repeat premutation at risk for?

A

Fragile X Tremor Ataxia Syndrome (FXTAS)

225
Q

What adult onset disorder are Female carriers with the fragile X/CGC repeat premutation at risk for?

A

Primary Ovarian Insufficiency (POI)

can cause premature menopause

226
Q

FMR-1 Related Disorders

A

FXTAS

POI

227
Q

How does full FMR-1 mutations differ between men and women?

A

All males with it will have Fragile x syndrome

However, some females with it will not have behavioral, cognitive, or physical features of Fragile x Syndrome

228
Q

Is Fragile X Syndrome a Dominant or Recessive X Linked Disorder?

A

Both Yet Neither!!

Used to be thought mothers passed it on, but women express it differently when only have one problematic X chromosomes so it is hazy

Just know the disorder is from a fragile site

229
Q

What are the characteristics of multi factorial inheritance disorders?

A

They are caused by multiple genes and environmental factors - but the exact number of genes is unknown

230
Q

Do multi factorial inheritance disorders follow a pattern?

A

No they do not follow a clear cut pattern of inheritance

disorders can be expressed during fetal life and be present at birth, or expressed later in life

231
Q

Examples of Multi Factorial inheritance Disorders

A

Cleft lip or palate

clubfoot

Congenital dislocation of the hip

congenital heart disease

pyloric stenosis

urinary tract malformation

232
Q

Cleft Lip or Palate

A

multi factorial inheritance disorder

can vary from a small notch in the vermillion border of the upper lip to complete separation from the palate to the floor of the nose

233
Q

Clubfoot

A

multi factorial inheritance disorder

internal rotation of foot around ankle

can be mild or severe

can be in one or both feet

234
Q

Congenital Dislocation of the Hip

A

“Developmental Hip Dysplasia”

multi factorial inheritance disorder

hip joint does not form easily and the ball is loose in the socket allowing easy dislocation

Most often present at birth but can develop in the first year of life

235
Q

Pyloric Stenosis

A

multi factorial inheritance disorder

thickening or swelling of the pylorus which causes severe forceful vomiting in the first few months of life

also called “Infantile Hypertrophic Pyloric Stenosis”

236
Q

Chromosomal Disorders

A

Major category of genetic disease counting for a large proportion of early miscarriages, intellectual disabilities, and congenital malformations

Can be from abnormal numbers of chromosomes in autosomes or sex chromosomes, or it can be related to alteration in the structure of one or more chromosomes

237
Q

What things can Chromosomal Disorders cause/manifest?

A

Reproductive Wastage

Congenital malformations

intellectual disability

*it is linked to 60+ identifiable syndromes present at birth

238
Q

Reproductive Wastage

A

early gestational abortions

239
Q

Types of Chromosomal Disorders

A

Structural Chromosome Abnormalities

Numeric Disorders involving Autosomes

Numeric Disorders involving Sex Chromosomes

240
Q

Examples of Numeric Chromosomal Disorders involving Autosomes

A

Trisomy 21

Monosomy X

Polysomy X

241
Q

Examples of Numeric Chromosomal Disorders involving Sex chromosomes

A

Turner Syndrome

Klinefelter Syndrome

242
Q

Trisomy 21

A

Downs Syndrome

Extra/3 chromosomes on position 21 rather than 2

Can occur on the 13th and 18th chromosomes but 21 is the most common

243
Q

Monosomy X

A

presence of only one member of a chromosome pair

mostly due to nondisjunction during meiosis

often leads to a spontaneous abortion when it is associated with autosomes

244
Q

Polysomy X

A

more than 2 chromosomes in a cell

245
Q

Turner Syndrome

A

Loss or partial loss of the X chromosome

Leads to early pregnancy loss with 99% not surviving first trimester

Usually only in girls as its missing an X chromosomes or part of a second X chromosome

246
Q

S/S of Turner Syndrome

A

At Female Sexual maturity, there is no ovulation or menstruation that occurs

short stature

congenital heart disease

bicuspid aortic valve and/or alteration of aorta

short webbed neck

247
Q

Klinefelter Syndrome

A

XXY karyotype - 47 - extra X chromosome

only in males

248
Q

S/S of Klinefelter Syndrome

A

Manifests as a teen and young adult

testosterones drops and follicle stimulating hormone increases (FSH)

249
Q

What is the most common chromosomal; abnormality?

A

turners syndrome

250
Q

mtDNA only comes from…

A

the mother

251
Q

All mtDNA disorders are inherited from…

A

the maternal line

mom can pass it to all children but only the daughters will pass the mutation to their children

252
Q

Clinical expression of a Mitochondrial Gene Disorder depends on what?

A

total content of mitochondrial genes and the proportion that are mutant

253
Q

How rare are mitochondrial diseases?

A

Very rare

as of September 2020 there were about 300 in existence

254
Q

What are the manifestations and s/s of a Mitochondrial Gene Disorder?

A

It often affects more than 1 body organ system

muscle weakness

stroke like episodes and seizures

activity intolerance

myocardial myopathy

most syndromes have similar symptoms due to it impacting the neuromuscular system

255
Q

Teratogenic Agents

A

Agents that produce abnormalities during embryonic or fetal development

It is a chemical, physical, or biological agent that produces these abnormalities

256
Q

What are some examples of Teratogens?

A

Radiation

Chemicals and Drugs

Infectious Agents

Folic Acid Deficiency (showing how not just exposure, but nutritional deficiency counts too)

257
Q

What are some example of chemical and drug teratogen exposure outcomes?

A

Fetal Alcohol Syndrome

Cocaine Babies

Folic Acid/Nutritional deficiencies

Prenatal smoking

258
Q

How does sensitivity vary over time to teratogens?

A

different systems have different sensitivities at different times of development

259
Q

When is the CNS most sensitive to teratogens?

A

About the first 2-4 weeks of development

260
Q

When is the Heart most sensitive to teratogens?

A

About 2.5 to 6th week of development

261
Q

When are the extremities most sensitive to teratogens?

A

about 3.5 to 7th week of development

262
Q

when are the eyes most sensitive to teratogens?

A

about 3.5 to the 7.5 week of development

263
Q

when is the external genitalia most sensitive to teratogens?

A

about the 6.5 to 8.5 week of development or so

264
Q

What are the components of a genetic assessment?

A

Assessment of Genetic Risk and Prognosis

Detailed Family History

Pregnancy History

Detailed Accounts of Birth Process

Accounts of Postnatal Health and Development

Physical Examination of Affected Child and Family

Laboratory Testing

265
Q

What are the 3 purposes of a prenatal diagnosis?

A

Information

Reassurance

Knowledge

266
Q

How does a prenatal diagnosis lead to information?

A

Provides parents with information needed to make informed choices about having a child with an abnormality

267
Q

How does a prenatal diagnosis lead to reassurance?

A

Provides reassurance and reduces anxiety among high risk groups

268
Q

How does a prenatal diagnosis lead to knowledge?

A

allows parents at risk to begin pregnancy with assurance that knowledge about the presence or absence of a disorder can be confirmed with testing

269
Q

Methods for Fetal Diagnosis

A

Maternal Blood Screening

Ultrasonography (non invasive allowing you to see soft tissue structures)

Obtaining Fetal Cells: Amniocentesis, Chronic Villus Sampling, Fetal Biopsy, Percutaneous Umbilical Fetal Blood Sampling

Cytogenic and Biochemical Analysis

270
Q

When is maternal testing recommended?

A

Between 11 and 13 weeks

271
Q

Amniocentesis

A

Invasive maternal testing for fetal diagnosis

can be done 13/14 to 20 weeks of pregnancy

Detects chromosomal abnormalities, neural tube defects, and genetic disorders

obtains fetal cells from the amniotic fluid via a needle

98-99% accurate but cannot determine severity of a birth defect

N361: Pathophysiology II (20 decks)

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