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Foundations exam 2 > Genetics > Flashcards

Genetics Flashcards

1
Q

Genes

A

hereditary units of DNA transmitted from one gen to another

code for proteins

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2
Q

locus

A

specific location of a gene on a chromosome

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3
Q

alleles

A

different versions of a gene

humans have 2 alleles for each autosomal gene

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4
Q

Chromosomes

A

structure composed of genes located in nucleus of cell
-chromosomes can be distinguished from ea. other by overall length and position of centromere (divides chromosome into 2 arms of varying length)

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5
Q

homologous chromosomes

A

have the same genes at the same loci

one maternal + one paternal

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6
Q

genome

A

genetic info contained in the cells, ont he chromosomesfor a particular species

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7
Q

Number of chromosomes in a human

A

46 (23 pairs)

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8
Q

Number of chromosomes in a garden pea

A

14

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9
Q

Number of chromosomes in a fruit fly

A

8

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10
Q

Mutation

A

a change in some part of the DNA code

  • can be spontaneous or induced by exposure to mutagenic chemicals or radiation
  • varying effects depending on where in the gene code mutation occured
  • net result= may change physical appearance or alter some other train
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11
Q

autosome

A

any chromosome that isnt a sex chromosome (humans have 22 paris)

allosome pair=sex chrom pair

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12
Q

chromosome number

A

Somatic cells contain one set of chromosomes from female parent and one homologous set from male parent

  • Homologous chromosomes are similar in size, structure, and gene composition
  • Humans have 22 pairs of autosomes, and 1 pair of sex chromosomes (allosomes) for 23 total pairs in each cell
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13
Q

haploid number

A

n= 23

number of chromosomes in sex cells/gametes

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14
Q

diploid nunber

A

2n=46

total number of chromosomes in somatic cells

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15
Q

which is the short arm of the chromosome?

A

p= short arm

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16
Q

which is the long arm of the chromosome?

A

q

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17
Q

how are chromosomes numbered?

A

numbered consecutively according to length beginning with longest chromosome first

exception= sex chromosome

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18
Q

Automsomes

A

somatic chromosomes

all except sex chromosomes

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19
Q

allosomes

A

sex chromosomes

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20
Q

what determines maleness?

A

genetic factors on the Y

males have one morphologically dissimilar pair of chromosomes

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21
Q

Karyotype

A

picture of persons chromosomes

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22
Q

mitosis

A

one exact cope of ea chromosome made and distributed through the division of original cell–> 2 daughter cells

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23
Q

Meiosis

A
  • The process by which gamete cells are produced (egg and sperm)
  • Resulting gametes have 23 new chromosomes (one member of each of the pairs), with new combos of the original maternal and paternal copies
  • Occurs only in specialized germ cells of gonads

-2 consecutive cell divisions producing cells with half the original chromosome number
diploid 2n—>haploid n

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24
Q

oogenesis

A

diploid primordial cells in ovaries become oogonia

=1 haploid ovum (n) and polar bodies, which degenerate

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25
Q

spermatogenesis

A

diploid primordial cells in testes become spermatogenia

=4 sperm cells (spermatozoa)–> ea haploid (n)

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26
Q

genotype

A

all of the alleles of an organism

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27
Q

phenotype

A

measurable trait an organism has

-result of gene products that interact in a given enviro

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28
Q

Patterns of inheritance

A

Describe how disease is transmitted in families

-The patterns help predict the risk for relatives

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29
Q

Patterns of inheritance- what are single gene disorders

A

-Single gene disorders (Mendelian disorders)

Classified by whether they are
Autosomal or x-linked
Dominant or recessive pattern

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30
Q

punnett square

A

illustrates monofactorial cross- mating where single gene is analyzed

-demonstrates mendels principle of segregation: one parent has 2 copies of a gene for ea trait, but transmits only one via a gamete

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31
Q

codominance

A

when 2 alleles for a trait are equally expressed (ex: AB blood type)
-When alleles lack complete dominant and recessive relationships and are both observed phenotypically (expressed at same time)

ex: roan cow, checkerd chickens

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32
Q

what type of inheritance is AB blood type?

A

codominance

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33
Q

incomplete dominance

A

heterozygotes have phenotypes that have both alleles visible as a blend (one allele isn’t expressed over the other)

Makes a third phenotype that’s a blending of the two
Human examples: wavy hair – it’s a blend that’s seen when a person with straight hair has a child with a person with curly hair;
-another ex: skin color

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34
Q

penetrance

A

the probability that individuals in a population who have a particular gene combination will show the condition

Example: if a mutation causing diabetes has 95% penetrance, 95% of people with the mutation combo will develop diabetes

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35
Q

genetic marker

A

Sequence of DNA with a known location on a chromosome

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36
Q

expression

A

the components of the phenotype that are exhibited in an individual

Example: myotonic muscular dystrophy
Phenotype may include myotonia, cataracts, narcolepsy, balding, infertility
–>2 people carrying this gene may express it differently

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37
Q

anticipation

A

Genetic diseases that increase in severity or have earlier onset with each successive generation

Examples: Fragile X, Huntington, myotonic muscular dystrophy

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38
Q

Chromosomal abnormalities: most common type

A

-can be numerical or structural

most common= aneuploidy (abnormal number)

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39
Q

Chromosomal abnormalities: balanced chromosomal abnormalities

A

no net loss or gain of chromosomal material

Balanced translocation or inversion

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40
Q

Chromosomal abnormalities: balanced chromosomal abnormalities–> Balanced translocation

A

rupture of a chromosome resulting in the pieces “re-sticking” in the wrong combinations

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41
Q

Chromosomal abnormalities: balanced chromosomal abnormalities–>inversion

A

a chromosome piece is lifted out, turned around, and reinserted

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42
Q

Chromosomal abnormalities: balanced chromosomal abnormalities–> Unbalanced chromosomal abormalities

A

additional or missing info

deletion or insertion

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43
Q

Unbalanced chromosomal abnormalities- unbalanced translocation

A

Tends to arise as an offspring of a balanced carrier

ex: Robertsonian translocation

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44
Q

Robertsonian translocation

A

ex of unbalanced translocation

  • involve 2 chromosomes
  • They are all acrocentric (centromeres are close to the end)
  • Results in formation of a “new” chromosome
  • The bigger chromosome can produce an unbalanced gamete
  • Those involving chromosome 21 can produce gametes with 2 copies; upon fertilization, can produce Trisomy 21
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45
Q

Why use 3 generation pedigree

A
  • Provides a concise visual tool
  • Multifactorial genetic conditions now require that treatment and prevention measures be highly individualized
  • PCP is at front line playing integral role in prevention and treatment of genetically based diseases
  • genetic testing is more available to patients
  • Many diseases with genetic links have been discovered and clarified
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46
Q

CONS of software pedigree programs

A

Many software pedigree programs available are actually less user friendly than drawing it out – harder to record nuances such as multiple relationships, > 3 generations, and tracking multiple diseases

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47
Q

Function of the 3 generation pedigree

A
  1. Making a diagnosis
  2. Deciding on testing strategies
  3. Establishing the pattern of inheritance
  4. Identifying people at risk
  5. Educating the patient
  6. Determining reproductive options
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48
Q

Purpose of 3 generation pedigree

A
  • Genetic family history recorded in shorthand form
  • How members are related to each other from generation to generation
  • Graphic representation of medical family history using symbols
  • Provides medical information and relationship information at a glance
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49
Q

Pedigree Standardization Task Force of the National Society of Genetics Counselors

A

Established in 1995, updated in 2008

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50
Q

standard pedigree language

A

Male -square

Female – circle

Diagonal line through symbol – deceased

Shaded symbol – affected with trait

Half-shaded symbol – carrier of trait

Relationship – line between individuals

Sibship – horizontal line showing siblings

Line of descent – line showing offspring

Individual line – attaches to sibship line

Two hash marks – divorced or separated (or no longer in a relationship)

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51
Q

siblings on a pedigree

A

draw siblings in birth order from left to right
includ either age or birth year

each gen goes on the same horizontal plane

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52
Q

Research pedigree

A

generations are given a roman numeral

-individuals given a number (1,2,3)

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53
Q

Clinical pedigree

A

Names recorded next to individual’s line

Surname recorded above sibship or relationship line
Initials often used

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54
Q

Autosomal dominant

A

65% of human monogenic disorders

  • mutation in a single allele can cause dz
    ex: Huntington’s Disease

affected= Hh or HH

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55
Q

Characteristics of Autosomal dominant

A
  1. Vertical pattern
  2. Multiple generations affected
  3. Variable expressivity
    - Affected individuals in same family may show varying degrees of phenotypic expression (severity)
  4. Reduced penetrance
    Some with the genetic mutation may not show phenotype, making it appear that it “skipped” a generation
  5. Males and females affected equally
  6. Male to male transmission can be seen
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56
Q

Autosomal recessive

A

25% of human monogenic disorders

Tends to involve enzymes or receptors

Rare

Males and females equally affected

Horizontal inheritance
-Multiple affected offspring

Often occurs in the context of consanguinity (blood related)

Heterozygous carriers of a defective allele are usually clinically normal

Example:
Cystic fibrosis

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57
Q

Characteristics of autosomal recessive

A

Horizontal pattern

Single generation affected

Males and females affected equally

Inheritance is from both parents, each being a heterozygote/carrier

Each offspring has a 25% chance of being affected, and a 50% chance of being a carrier

Higher association with consanguity (blood relative)

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58
Q

X-linked

A

5% of human monogenic disorders

Risk of developing disease due to a mutant x

chromosome differs between the sexes

Males are hemizygous (heterozygous) for mutant allele on the x

The terms “x-linked dominant” and “x-linked recessive” therefore only apply to females

Heterozygous females usually normal or mild

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59
Q

Who is more likely to develop a mutant phenotype in x-linked disorders?

A

Men

Males are hemizygous (heterozygous) for mutant allele on the x

More likely to develop a mutant phenotype regardless if the mutation is dominant or recessive

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60
Q

Who does “x-linked dominant” and “x-linked recessive” apply to?

A

Females only!

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61
Q

What is not possible in x-linked disorders?

A

No male to male transmission is possible

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62
Q

Males and x-linked disorders

A

No male to male transmission is possible

Unaffected males do not transmit the phenotype

All daughters of an affected male are heterozygous carriers

Males usually more severely affected than females

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63
Q

Examples of x-linked dominant disorders

A

Alport’s Syndrome

Fragile X Syndrome

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64
Q

Examples of x-linked recessive disorders

A

Wiskott-Aldrich Syndrome

Duchenne muscular dystrophy

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65
Q

Multifactorial/Complex disease

A

Caused by interactions of variations in multiple genes and environmental factors

Genetic susceptibility genes
–>These genes make a person susceptible to a disorder, and certain environmental factors trigger the susceptibility

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66
Q

Examples of Multifactorial/Complex disease

A 
Cancer
Diabetes
Asthma 
Heart disease
Mental illness
Cleft lip/cleft palate
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67
Q

Multifactorial/Complex disease- cancer

A

Sporadic inheritance of a cancer vs. inherited cancer syndrome for which a genetic test may be available (ex: BRCA)

  • Sporadic cancer is more likely
  • Most cancer is NOT inherited, but the predisposition to cancer IS inherited (ie BRCA)

The pedigree can help the clinician make more cost-effective, appropriate choices in genetic testing
-Determine who needs to be tested first, and who else needs to be tested

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68
Q

Down syndrome

A

Trisomy 21- gamete has 2 copies of chromosome 21 (leads to trisomy when fertilized)

Most common chromosomal abnormality in live births

Most common non-lethal trisomy

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69
Q

Prenatal testing for Down Syndrome

A
  • Quad screen (maternal serum AFP, estriol, hCG, inhibin-alpha)
  • Nuchal translucency
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70
Q

What causes Down Syndrome?

A

Trisomy 21 is cause of 95% of cases of Down Syndrome

4% due to Roberstonian translocation

71
Q

Down Syndrome- When are parental chromosome studies indicated

A

indicated if trisomy was due to an unbalanced translocation

72
Q

What is the prevalence of Down Sydrome

A

1:500 pregnancies

Increase incidence with advancing maternal age
Age 35 1:400
Age 45 1:35

73
Q

Symptoms of Down Syndrome

A

Intellectual disability

Characteristic facial appearance

40% have cardiac defects

75% hearing loss

> 50% visual problems

7% have GI defects

Increased social skills in childhood as long as Syndrome isn’t severe

Half of adults with Down syndrome develop Alzheimer disease

74
Q

Trisomy 18

A

AKA Edwards Syndrome

Second most common autosomal trisomy after trisomy 21 that goes to full term

Many die before birth or in first month

75
Q

What is Trisomy 18 from

A

Usually from 3 copies of 18, but translocation can occur

76
Q

Characteristics of Trisomy 18

A

Kidney and heart defects

Developmental delay

Club foot (Rocker bottom feet)–> hallmark sign

Low set ears, small jaw

clenched hand with overlapping fingers

77
Q

Incidence of Trisomy 18

A

1:5000 live born infants

Increased risk with advanced maternal age

IUGR

78
Q

Survival rate of Trisomy 18

A

Highly lethal in-utero – 85% lost between 10 weeks’ gestation and term

50% die in first week of life

2% 1 year survival rate

Heart, GI, kidney defects

79
Q

Trisomy 13

A
  • Patau syndrome
  • Severe intellectual disability
  • Many physical abnormalities
  • Cleft lip or palate
  • Seizures
  • Small jaw
  • Polydactyly
  • Heart defects, brain/spinal
80
Q

What is the incidence of Trisomy 13

A

1: 16,000 live births

Increased risk with advanced maternal age

81
Q

Survival rate of Trisomy 13

A

cord abnormalities

-Many children die within first days or weeks of life

82
Q

Etiology of Trisomy 13

A
  • Most cases of Trisomy 13 from 3 copies of chromosome 13

- Some caused by Robertsonian translocation involving chromosomes 13 and 14

83
Q

Cri-du-Chat Syndrome

A

Chromosomal abnormality: deletion of part of short arm of chromosome 5

Partial monosomy – when only a portion of a chromosome has one copy instead of two

Most cases are from a spontaneous mutation

1:50,000 births

Can be detected in utero with CVS (chorionic villi sampling)

84
Q

What is the characteristic sign of Cri-du-Chat Syndrome?

A

Cat-like cry of affected children due to abnormal larynx development

85
Q

Physical appearance of person with Cri-du-Chat syndrome?

A

Intellectual disability, wide set eyes, low ears

86
Q

Klinefelter’s Syndrome

A

Extra X chromosome, 47 XXY–> so MEN

Occurs during gametogenesis

Affects male physical and cognitive development

Accounts for many first trimester losses

Physical traits become more apparent after puberty (will have some female characteristics)

Most common sex chromosome aneuploidy in males

Hypogonadism, infertility (b/c testicles not developing properly)

Gynecomastia(abnormal breast tissue in men), reduced hair

87
Q

Turner Syndrome

A

45 X, affects development in females (does not affect males)

Monosomy

88
Q

Characteristics of Turner Syndrome

A

Gonadal dysgenesis–> non-functional ovaries

Short stature

Broad chest

Webbed neck

Amenorrhea

Infertility

Cardiovascular abnormalities

89
Q

Huntingtons disease

A

A neurodegenerative disease – progressive brain disorder

90
Q

What Huntingtons disease causes

A

Causes uncontrolled movements
emotional problems
loss of thinking ability,
changes in personality

Involuntary jerking movements- Chorea

91
Q

Early signs of Huntington’s Disease

A

depression, irritability, poor coordination, trouble learning

92
Q

When do you see Huntington’s Disease

A

-Latent for a long time

Adult onset: genetic defect is latent for 3-5 decades, then manifests as progressive neuronal dysfunction

93
Q

Etiology of Huntington’s Disease

A

Genetic defect: HD gene on chromosome 4 that codes for a unique protein called huntingtin

  • CAG trinucleotide repeat
  • Normal: 10-35 repeats
  • In HD: 36-120 repeats
  • Abnormal protein causes microscopic deposits of protein in neurons
  • Most cases are inherited, but some occur as new spontaneous mutations (so MUST offer genetic counseling to offspring)
94
Q

What is the average time from symptom onset to death in Huntingtons disease

A

15 years

95
Q

Mode of inheritance of Huntington’s disease

A

Autosomal dominant

If one parent has the disorder, each child has a 50% chance of manifesting it

Only human disorder of complete dominance
***Heterozygotes are just as affected clinically as homozygotes (HH, Hh)

96
Q

Alzheimer’s Disease

A

A neurodegenerative disease

Most common form of dementia in older individuals

65% of dementia from Alzheimer’s Disease
35% of dementia are vascular in nature

97
Q

Alzheimer’s Disease- age of onset, population

A

Usually begins after age 60; risk increases with age

Death usually occurs within 10 years

People with parent, sibling, or child with AD are at increased risk

98
Q

Pathophysiology of Alzheimer’s disease

A

Loss of cholinergic neurons in brain (loss of acetylcholine)

Formation of plaques and tangles

Atrophy of brain

Resultant effect – blocked communication

99
Q

Mode of inheritance of Alzheimers disease

A

Several gene mutations cause predisposition to AD

100
Q

Clinical manifestations of Alzheimers disease

A

Progressive mental deterioration: memory loss, confusion, disorientation

101
Q

The two forms of Alzheimers disease

A

familial (early onset) and sporadic (late onset)

102
Q

Familial Alzheimer’s Disease

A

Also called early onset AD

Many members of multiple generations affected

Symptoms start before age 65

Mutations on chromosomes 1, 14, or 21

Induce formation of a “sticky” protein that forms clumps in the brain

Rare - <5% of cases of AD

Autosomal dominant
50% chance of developing early onset AD if one parent has it

103
Q

Sporadic Alzheimer’s Disease

A

Also called late onset AD

  • Usually develops after age 65
  • Accounts for most cases of AD

One gene has been shown to increase risk

  • Chromosome 19 apolipoprotein E (APOE) gene
  • Not everyone carrying the gene develops disease

*Definitive diagnosis: autopsy-plaques and tangles

104
Q

Risk factors of Hereditary breast and ovarian cancer syndrome

A

Gender
Age
Family history

105
Q

Mode of inheritance of Hereditary breast and ovarian cancer syndrome

A

Up to 10% of breast and ovarian cancers are caused by known predisposing genetic factors

106
Q

Clinical manifestations of Hereditary breast and ovarian cancer syndrome

A

Early age of breast cancer onset (< 50)

FH of both breast and ovarian cancer

Increased bilateral cancers

Increased development of both cancers in same person

Increased incidence of prostate cancer in family

Male breast cancer

107
Q

Overview of BRCA1/2

A

tumor suppressor genes

Normally control cell growth and death, and DNA repair and stability

If a person has one mutated copy of either gene, their cancer risk goes up

Second gene associated with breast cancer
BRCA2 on chromosome 13
Mutations is inherited in autosomal dominant manner
Associated with male breast cancer, ovarian cancer, prostate cancer, and pancreatic cancer

108
Q

BRCA1

A

First gene associated with breast cancer

  • ->BRCA1 on chromosome 17
  • ->Mutation is inherited in autosomal dominant manner
  • ->Not all families with this gene get hereditary breast cancer
109
Q

BRCA2

A

Second gene associated with breast cancer

BRCA2 on chromosome 13

Mutations is inherited in autosomal dominant manner
–>Associated with male breast cancer, ovarian cancer, prostate cancer, and pancreatic cancer

110
Q

Hereditary Breast and Ovarian cancer syndrome- genetic testing

A

Preferable to first test an individual who is affected by cancer before testing unaffected family members

Helps to identify whether a detectable BRCA1 or BRCA2 mutation could be responsible for the cancer

An individual can inherit a BRCA1 or BRCA2 mutation yet never develop cancer

111
Q

Colorectal cancer

A

Genetic+ environmental factors

Genetic predisposition is the main risk factor in only a small proportion of people

Diet, exercise, smoking, obesity are stronger risk factors in most people

112
Q

Colorectal cancer- familial inheritance

A

May occur sporadically or from familial inheritance

  • Most are from sporadic mutations and occur randomly
  • Many cancer syndromes include colon cancer
113
Q

Types of colon cancer

A
  1. Familial colorectal cancer

2. Hereditary colorectal cancer syndromes

114
Q

Hereditary colorectal cancer syndromes

A

Arise from specific mutations in genes that code for susceptibility to cancer

  • ->Familial adenomatous polyposis (FAP) <1% of colon cancers
  • ->Hereditary nonpolyposis colorectal cancer (HNPCC, Lynch Syndrome) 2-3%
115
Q

Familial colorectal cancers

A

Patterns within a family that exist without identifying a specific mutation are labeled as familial colorectal cancers

A family history of 1+ people with colorectal cancer or premalignant polyps is considered a positive FH

116
Q

Familial colorectal cancer- causes

A

May be due to:

  • Chance alone
  • Shared exposure to a carcinogen or diet/lifestyle factors
  • Combination of gene mutations and environmental risk factors
117
Q

\Familial adenomatous Polyposis (FAP) gene

A

<1% of all colorectal cancers

Genetic mutation: mutation in APC (adenomatous polyposis coli) gene

  • ->Hundreds to thousands of polyps in colon beginning in adolescence
  • ->APC is a tumor suppressor gene on chromosome 5
  • ->Cancers develop in 20’s
  • ->Risk of developing colorectal cancer is near 100%, usually before age 50
  • ->Time from polyp to cancer development is 10+ years
118
Q

Mode of inheritance of Familial adenomatous Polyposis (FAP) gene

A

autosomal dominant

50% chance of passing it to each offspring

119
Q

Mode of inheritance of Familial adenomatous Polyposis (FAP) gene–> genetic counseling and testing

A

Should be offered to all patients with a suspected diagnosis of FAP as identified by colonoscopy

Should also be offered to all relatives at risk

Children of patient with FAP should have genetic screening by age 10 years

120
Q

Tx of FAP

A

Once diagnosis of FAP is established, total colectomy is recommended before age 20 years

121
Q

Hereditary Nonpolyposis colorectal cancer (HNPCC)

A

Also called Lynch Syndrome

2-3% of all colorectal cancers

122
Q

Pattern of inheritance of Hereditary Nonpolyposis colorectal cancer (HNPCC)

A

autosomal dominant
Genetic mutation: a mutation in one of many genes that code for DNA repair

More rapid transition from adenoma to cancer than FAP – cancers occur earlier, 30’s and 40’s

123
Q

Hereditary Nonpolyposis colorectal cancer (HNPCC) –> Nonpolyposis

A

refers to the fact that colorectal cancer can occur when a small number or no polyps are present

124
Q

Rate of incidence of Hereditary Nonpolyposis colorectal cancer (HNPCC)

A

Approx. 50% chance of cancer in women, approx. 70% in men

125
Q

Hereditary Nonpolyposis colorectal cancer (HNPCC)-Association with other cancers

A

Associated with the formation of other cancers

Uterus, ovaries, stomach, urinary tract, small bowel, bile ducts

126
Q

What to do if genetic testing + for Hereditary Nonpolyposis colorectal cancer (HNPCC) gene mutation

A

Regular colonoscopy starting age 25 for relatives
–>Or beginning 5 years younger than the age of diagnosis of the youngest affected family member

Upper endoscopy every 2 years to screen for gastric cancer

Screening for endometrial and ovarian cancer in women at age 25-35

127
Q

Chronic Myelogenous leukemia

A

A myeloproliferative disorder

Genetic defect
Translocation between chromosomes 9 and 22
Philadelphia chromosome (22)

**Produces a protein that codes for an enzyme that causes too many stem cells to develop into WBCs

Acute myelogenous leukemia is life threatening

128
Q

Chronic Myelogenous leukemia- rate of incidence

A

More common in men

Median age at presentation is 55 years

129
Q

Pathophysiology of Chronic Myelogenous leukemia-

A

Increased production of abnormal white blood cells that are nonfunctional

These large numbers of abnormal WBCs take up bone marrow space meant for healthy WBCs, RBCs, and platelets

130
Q

Clinical presentation of Chronic Myelogenous leukemia

A

Insidious onset, slow progression over months to years of infections, anemia, complications of bleeding (most likely have low platelet counts)

Fever, night sweats fatigue (“B symptoms”)

131
Q

Diagnosis of Chronic Myelogenous leukemia

A

Bone marrow aspiration and then assess for karyotype

132
Q

Hemophilia

A

Bleeding disorders caused by mutations in genes that code for coagulation proteins

Mutation on F8 or F9 genes, located on the X chromosome

133
Q

Hemophilia- Mutation on F8 gene

A

Mutation in F8 gene causes factor VIII deficiency

Results in hemophilia A (classic hemophilia)

More common

134
Q

Hemophilia- Mutation on F9 gene

A

Mutation in F9 gene causes factor IX deficiency

Results in hemophilia B (Christmas Disease)

135
Q

Pattern of inheritance of Hemophilia

A

X-linked recessive pattern

Genes associated are on the X chromosome

Most people affected are males

136
Q

Clinical manifestations of Hemophilia

A

hemarthrosis (spontaneous bleeding into a joint)–> most common clinical manifestation

bleeding into muscles, and other soft tissues after injury or trauma;

prolonged bleeding or oozing of blood after injury or surgery

Severity of symptoms can be variable

137
Q

Sickle Cell disease- pathophysiology

A

Atypical hemoglobin molecules (hemoglobin S)

Distorts the red blood cell into a crescent shape

Abnormally shaped RBCs break down prematurely
Mutation on HBB gene

138
Q

Sickle Cell disease- Clinical manifestations

A

CP
Anemia, infections, episodic pain

Shortness of breath, fatigue, delayed growth

Generally will present with sickle cell crisis

139
Q

Inheritance of Sickle cell disease

A

Autosomal recessive

Most common in people whose ancestors came from:
Greece, Africa, Turkey, Italy, Arabian Peninsula, India, South America, Central America, Caribbean

140
Q

Cystic Fibrosis- Pattern of inheritance

A

autosomal recessive

Two copies of mutated gene are needed for disease to be expressed

141
Q

Cystic Fibrosis- Genetic mutation involved

A

mutation in the CFTR gene (cystic fibrosis transmembrane conductance regulator)

CFTR codes for a protein that regulates chloride channels in epithelial cells

When mutated, a defective protein is made, causing a disruption of chloride and water transport - water balance in secretions is disrupted

142
Q

Clinical manifestations of Cystic Fibrosis

A

Causes thick, sticky mucous obstructing airways in lungs and ducts in pancreas

Can affect pancreas, intestines, GU tract, hepatobiliary system, and exocrine glands

143
Q

Clinical manifestations of Cystic Fibrosis–> symptoms

A

Difficulty breathing, infections in lungs

Problems with nutrient digestion

Buildup of mucous prevents pancreatic enzymes from reaching intestine

Failure to thrive, poor growth rate

Meconium ileus – newborn intestinal obstruction due to thick fecal waste products

144
Q

What is the most common cause of morbidity associated with Cystic fibrosis

A

pulmonary disease

Pulmonary system can’t defend against pathogens well – leads to sinusitis and bronchitis

Nasal polyps, nosebleeds, chronic sinus infections common in CF patients
Thick mucous builds up in lower airways causing obstruction

145
Q

Disease incidence of Cystic Fibrosis

A

Common genetic disease in the white population in the US

Disease incidence: 1 in 3500 white newborns

Carrier incidence: 1 in 25

Most cases diagnosed by age 1

146
Q

How do you diagnose Cystic Fibrosis

A

Sweat chloride test – primary test for diagnosis

Defective chloride channel doesn’t allow chloride to be reabsorbed
-Concentration of chloride in sweat is elevated in CF

Genetic testing used to confirm results

147
Q

Marfan syndrom- mode of inheritance

A

autosomal dominant

Results from either an inherited mutation or a new mutation of the fibrillin-1 gene (FBN1)

148
Q

Results of Marfan Syndrome

A 
Causes defects in connective tissue affecting multiple systems
Bones
Ligaments
Muscles
Blood vessels
Heart valves
149
Q

Clinical Manifestations of Marfan Syndrome

A 
Tall stature
Long, thin arms and legs
Arm span wider than body height
Long, narrow face
High arched palate
Overcrowded teeth
Scoliosis
Hyperflexible joints
Chest deformities (barrel chest)
150
Q

Primary features of Marfan syndrome

A
  • vision problems because of dislocated lens

- Aortic aneurysm/dissection

151
Q

What is the major cause of morbidity and mortality in Marfan Syndrome

A

Heart defects

Mitral valve prolapse, aortic valve regurgitation
–>Both of these can cause SOB, fatigue, palpitations

152
Q

What do you advise patients with Marfan Syndrome

A

Affected individuals are advised to avoid contact sports, caffeine, and decongestants due to increased stress placed on CV system

153
Q

Neurofibromatosis Type I

A

Also called von Recklinghausen disease

154
Q

Pattern of inheritance of Neurofibromatosis Type I

A

autosomal dominant

Tumor suppressor gene

155
Q

Pattern of inheritance of Neurofibromatosis Type I –> what mutation results in

A

Growth of neurofibromas - benign tumors that grow on nerves of skin and brain
Changes in skin pigmentation

156
Q

Pattern of inheritance of Neurofibromatosis Type I – what is the most common type (along with clinical manifestations)

A

NF-1 is most common type

  • Subcutaneous tumors
  • Hyperpigmented skin lesions called café-au-lait spots
  • Flat patches on skin darker than surrounding area
  • Lisch nodules in iris
  • Freckles in axillae and groin
157
Q

Diagnositic features of Neurofibromatosis Type I

A

1.5 cm or larger café-au-lait spot post puberty or 6 or more café-au-lait spots 0.5 cm or larger in before puberty

2 or more neurofibromas to be diagnosed

Axillary or inguinal freckling (Crowe sign)

Optic glioma

2 or more Lisch nodules

1st degree relative with NF1

158
Q

Polycystic kidney disease- pathophysiology

A

Clusters of fluid filled sacs develop in kidneys

Affects ability to filter the blood properly

Kidneys become enlarged and can fail (2nd most common cause of kidney transplant)

159
Q

Polycystic kidney disease- Clinical manifestations

A

Hypertension
Back pain (b/c kidneys getting bigger and putting strain on back)
Hematuria
UTIs, kidney stones

160
Q

Other associations of Polycystic kidney disease

A

Liver cysts
Heart valve abnormalities
Increased risk of aortic aneurysm and brain aneurysm

161
Q

Polycystic kidney disease- 2 forms

A

Autosomal dominant

Autosomal recessive

162
Q

Polycystic kidney disease- Autosomal dominant

A

sx start in adulthood
1 in 1000; PKD1 and PKD2 genes
Usually inherited (90% of the time)

163
Q

Polycystic kidney disease- Autosomal recessive

A

rare, lethal early in life
1 in 30,000
PKHD1 gene

164
Q

Congenital abnormalities

A

Approximately 10% of all newborns have some birth defect
–>Ranges from minor biochemical problem to severe physical deformity

Caused by variety of biological, chemical, and physical agents
–>Contributors: mutant genes, chromosomal defects, multifactorial components

165
Q

What is the biggest cause of birth defects?

A

unknown etiology!

166
Q

Congenital abnormalities- teratology

A

Teratology= study of abnormal development

Teratogens- anything capable of disrupting embryonic or fetal development and producing malformations
Teratogenic, teratogenicity

167
Q

Congenital abnormalities- What is the critical period for teratogenic effects

A

3-16 weeks

brain starts to develop at 3 weeks

Timing of exposure determines which systems are affected

Example – CNS begins to develop in 3rd week, while teeth and palate begin to form in 6th-7th week

168
Q

Newborn screening

A

Performed on all newborns

Biochemical analysis that determines whether certain proteins (enzymes) are present or absent

These are typically autosomal recessive conditions
Referred to as “inborn errors of metabolism”
–>Inherited defect in one or more enzymes

Newborn screening checks for many of these metabolic disorders

A law in 2008 was enacted to increase testing and make more uniform among states

169
Q

Newborn screening- the Arizona Panel

A 
The federally recommended uniform screening panel of 30 disorders (including hearing loss):
Endocrine Disorders
Hemoglobinopathies
Other Enzyme Deficiencies
Amino Acid Disorders
Fatty Acid Oxidation Disorders
Organic Acid Disorders
Cystic Fibrosis
Hearing Loss
170
Q

Newborn screening- First and second test

A

1st: baby is 24-36 hours old
2nd: 1st office visit, b/w 5-10 days

171
Q

Who are genetic counselors employed by Employed by>

A

physician offices, medical centers, advocacy organizations, governmental agencies, public health departments, biotech companies

172
Q

Medical geneticist

A

Clinical genetics specialist

Practice of clinical medicine with regard to hereditary disorders

Recognized by the American Board of Medical Specialties

Residencies in clinical genetics are accredited by the American Council of Graduate Medical Education

Applicants must be M.D. or D.O. who has already completed 24 months of another residency

173
Q

Genetic counselor

A

Master’s trained health care professionals

Skilled in genetic risk assessment, education, counseling

Foundations exam 2 (2 decks)

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