Additional Info

Question 1

Monosomy

Answer 1

– loss of one chromosome, depicted by the question
2n-1
N=#chromosomes
Humans have 23 paired chromosomes; thus norm is 46
45 chromosomes

Question 2

Sex chromosome aneuploidy:

Answer 2

Turner syndrome – loss of an X chromosome

Typically occurs with females

Question 3

Klinefelter syndrome – a form of trisomy

Answer 3

occurs in males with presence of an extra X chromosome
Characterized by presence of infertility; decreased testicular size; decreased facial and pubic hair; reduction of muscle strength; metabolic syndrome

Question 4

Trisomy

Answer 4

Trisomy – addition of a chromosome or chromosomal segment; depicted by equation 2n + 1

Question 5

Trisomy 18

Answer 5

Edwards syndrome (microcephaly, misshaped ears, cleft palate; cardiac defects)

Question 6

Trisomy 21

Answer 6

Down syndrome (see next slide for characteristics)

Question 7

missense mutation

Answer 7

changes one nucleotide [one letter] and consequently one amino acid [one word], for example: ‘ONE CAN NOT SEE THE SUN FOR THE DOG’. That creates a different meaning, but the sentence is still readable. There is a substitution of one amino acid for another.

Question 8

nonsense mutation

Answer 8

nonsense mutation results in a breakup of the text: ‘ONE CAN NOT SEE THE XXX’. Always results in premature termination (stop codon).

Question 9

in-frame mutation

Answer 9

in-frame mutation [e.g.: deletion of three letters] may or may not affect the meaning of the sentence: ‘ONE CAN NOT SEE THE SUN FOR FOG’. [missing ‘the’ before fog].

The deletion or insertion of multiples of three causes the deletion or insertion of amino acids in the translated protein but does not affect the reading frame beyond the mutation; the deletion/insertion is said to be ‘in frame’.

Question 10

frameshift mutation

Answer 10

A frameshift mutation [e.g.: deletion of one letter] changes the reading frame and make the sentence unreadable: ‘ONE CAN OTS EET HES UNF ORT HEF OG’ [when one letter/amino acid is deleted/removed, there is a shifting of all the other letters/amino acids…remember amino acids are always in groups of three].
So gains or loss of nucleotides in a number not divisible by three constitutes a frameshift mutation, which destroys the entire reading frame beyond the mutation and leads to the continued integration of incorrect amino acids, generating a completely abnormal protein.

Question 11

Cell summary overview

Answer 11

The cell cycle consists of the 3 stages of Interphase (G1, S G2) & Cell Division (mitosis or meiosis). Chromosomes are replicated during the S (synthesis) stage. Cell division is made up of 5 phases (prophase, metaphase, anaphase, telophase, cytokinesis).
Mitosis results in two identical daughter cells – each with 46 (diploid) chromosomes.
Meiosis (male or female) results in gametes that each contain 23 (haploid) chromosomes (1 copy of each autosome & 1 sex chromosome).
During fertilization, the egg & sperm unite & the full complement of chromosomes (46) is restored. Each of us receives one copy of each chromosome pair from our mother & the other from our father.

Question 12

Abbreviations

Answer 12

DNA- deoxyribonucleic acid
FISH- fluorescence in situ hybridization
GWAS –genome wide association study
mRNA–messenger RNA
RNA-ribonucleic acid
rRNA –ribosomal RNA
SNP- single nucleotide polymorphism
tRNA–transfer RNA

Question 13

Tumor suppressor gene:

Answer 13

Tumor suppressor gene: a gene that codes for a product that controls cell growth.
Variable expressivity: differing degree of clinical phenotypes in individuals with mutations in the same gene.

Question 14

Triploidy

Answer 14

an extra set of chromosomes due to the fertilization of one egg by two sperm, or the fertilization of an egg which then divides into two resulting in an embryo with 69 chromosomes. This is generally incompatible with life.

Question 15

Transcription Factor Modulators:

Answer 15

Medications that affect the levels of gene transcription in the body.

Question 16

Transcription Factors:

Answer 16

Regulatory proteins that bind to the promoter region at the beginning of a gene, thereby activating the gene.

Question 17

Transfer RNA (tRNA):

Answer 17

Carries appropriate amino acids to the template mRNA strand so that protein formation can occur.

Question 18

Transcription:

Answer 18

The process of “reading” a gene to creating a chain of mRNA from a template strand of DNA.

Question 19

Splicing:

Answer 19

The process of removal of non-coding parts of messenger RNA (introns) and joining together of the coding parts (exons) to produce the instructions to make a protein.

Question 20

Single Nucleotide Polymorphism (SNP):

Answer 20

: A nucleotide change present in more than 1% of the population.

Question 21

Ribosomal RNA (rRNA):

Answer 21

Functions to produce ribosomes, which are the machinery for protein formation to occur.

Question 22

Ribonucleic Acid (RNA):

Answer 22

A single-stranded molecule implicated in coding, decoding, regulation, and expression of genes.

Question 23

Proto-oncogene:

Answer 23

A gene that regulates cell proliferation and may be a transcription factor, growth factor, or other growth-promoting agent.

Question 24

Preimplantation Genetic Diagnosis:

Answer 24

The screening of embryos produced through in vitro fertilization for the presence of genetic or chromosome abnormalities.

Question 25

Pharmacogenomics:

Answer 25

The study of how genetic variants affect an individual’s responses to medications.

Question 26

Penetrance:

Answer 26

The proportion of individuals who inherit a mutation that will have clinical symptoms.

Question 27

Mitochondrial DNA:

Answer 27

: DNA located in the mitochondria, organelles within eukaryotic cells that convert chemical energy from food into adenosine triphosphate (ATP).

Question 28

Mosaicism:

Answer 28

The presence of more than one genetic cell line in a person.

Question 29

Neurofibromatosis:

Answer 29

An autosomal dominant genetic condition causing progressive neurocutaneous lesions.

Question 30

Messenger RNA (mRNA):

Answer 30

The template for protein synthesis, carrying genetic information from DNA to ribosomes.

Question 31

Marfan Syndrome:

Answer 31

A genetic disorder caused by a mutation in a connective tissue gene, resulting in skeletal, ocular, and cardiac abnormalities.

Question 32

Karyotyping:

Answer 32

Identifying the visual appearance of chromosome structure and number, often used in genetic diagnosis.

Question 33

Hybridization:

Answer 33

The process of joining two complementary single strands of DNA or RNA, or one of each, to form a double-stranded nucleic acid.

Question 34

Gonadal Cells:

Answer 34

Egg and sperm cells involved in reproduction.

Question 35

Genome-Wide Association Study (GWAS):

Answer 35

A genomic test used in research and clinical practice to identify relationships between common genome variations and specific traits of interest.

Question 36

Genetic Imprinting:

Answer 36

The differential expression of genes based on whether they are inherited from the mother or father.

Question 37

Fluorescence In Situ Hybridization (FISH)

Answer 37

A test using fluorescent probes to detect chromosome number and target specific DNA sequences on chromosomes.

Question 38

Epigenome:

Answer 38

The collection of chemical compounds (not part of genomic DNA) that instruct the genome where and when genes are expressed within a cell.

Question 39

Epigenetics:

Answer 39

The external modifications of DNA that affect gene expression without altering the DNA sequence itself, playing a role in gene regulation and inheritance.

Question 40

Cytogenetics

Answer 40

The study of chromosome number and structure, often used in the diagnosis of genetic disorders.

Question 41

Cystic Fibrosis

Answer 41

A genetic disorder characterized by impaired ion transport by epithelial cells, resulting in thick secretions that obstruct airways, pancreatic ducts, and other passageways in the body.

Question 42

Central Dogma:

Answer 42

The process of conversion of DNA to RNA to Protein, representing the flow of genetic information in cells.

Question 43

Chromosome Nondisjunction:

Answer 43

The failure of chromosomes to separate properly during cell division, leading to an abnormal number of chromosomes in daughter cells.

Question 44

Barr Body:

Answer 44

The inactivated X chromosome in each cell, a result of X chromosome inactivation in females.

Question 45

Anti-sense Oligonucleotide:

Answer 45

A sequence of complementary nucleotides that can bind directly to a target gene sequence to block the production of the gene product.

Question 46

Isolated:

Answer 46

A medical trait that appears to occur alone, without accompanying co-findings.

Question 47

Mutations:

Answer 47

Changes in the DNA code that can be beneficial, neutral, or harmful (e.g., disease-causing).

Question 48

Proband:

Answer 48

The person who has brought the condition in question to medical attention, often the first person diagnosed in a family.

Question 49

Variable Expressivity:

Answer 49

The different ways the same disease or disease-causing mutation can affect individuals, even within the same family, leading to variations in severity and presentation.

Question 50

Segregation

Answer 50

The distribution of genes during the formation of an egg or sperm. Each person has two versions (alleles) of each gene but contributes only one version (allele) to each egg or sperm cell.

Question 51

Syndrome

Answer 51

A collection of multiple signs and symptoms that, when present together, constitute the clinical picture of a disease.

Question 52

Aneuploidy

Answer 52

Wrong number of chromosomes present in embryo

Question 53

Aggregation

Answer 53

The clustering of a disease within a family, common in complex diseases like diabetes, which do not follow patterns of inheritance typical of single-gene disorders.

Question 54

Blue Sclerae:

Answer 54

A blue-gray tint in the whites of the eyes (sclera), often seen in genetic conditions like osteogenesis imperfecta.

Question 55

Independent Assortment:

Answer 55

The principle that different genes are distributed independently into egg and sperm during meiosis, leading to genetic diversity in offspring.

Question 56

Neurosusceptibility variants [CNVs]

Answer 56

-associated with a spectrum of psychological, emotional and behavioural disorders including intellectual disability, autism, epilepsy, attention deficit disorder and learning disabilities.
-Neurosusceptibility variants show enormously variable penetrance and there is a wide spectrum of severity: some people may never know that they carry a CNV as they have mild or no features.
-There are only a few neurosusceptbility variants associated with adult-onset health implications.
-There is a high de novo rate, they generally follow an autosomal dominant pattern of inheritance with extremely variable penetrance.