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Foundations > Genetic Diseases > Flashcards

Genetic Diseases Flashcards

1
Q

what is the most common chromosomal abnormality in live births

A

Down syndrome

95% caused by Trisomy 21, 4% caused by Robertsonian translocation

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2
Q

What is Trisomy 21 linked to

A

advancing maternal age
Age 35= 1:400
Age 45= 1:35

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3
Q

How can you test for Trisomy 21

A 
Quad screen (maternal serum AFP, estriol, hCG, and inhibit-alpha)- levels can be too low or too high
Nuchal translucency- added to results of quad screen for accuracy
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4
Q

What is nuchal translucency

A

an ultrasound done on baby in mom’s tummy checking thickness of neck. the thicker the neck, the more likely the baby is of having trisomy 21

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5
Q

How does Trisomy 21 develop

A

a gamete has two copies of chromosome 21, leading to a trisomy when fertilized

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6
Q

When are parental chromosome studies indicated

A

when the trisomy was due to an unbalanced translocation

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7
Q

What is the prevalence of Trisomy 21

A

1:500 pregnancies

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8
Q

What are possible effects of Down Syndrome

A

intellectual disability, characteristic facial appearance, 40% have cardiac defects, 75% have hearing loss, 50% have visual problems, 7% have GI defects, increased social skills in childhood

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9
Q

What do half of adults with Down Syndrome develop

A

Alzheimer disease

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10
Q

What is the second most common form of autosomal trisomy that goes full term

A

Trisomy 18- Edwards syndrome

85% lost between 10 weeks gestation and term, 50% die in first week of life, 2% survive to 1 year

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11
Q

What are characteristics of Edwards Syndrome

A

Rocker bottom feet

Kidney/Heart defects, developmental delay, club foot, low set ears/small jaw

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12
Q

What is the incidence of Trisomy 18

A

1:5000 live born infants

Increased risk with maternal age

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13
Q

What is Trisomy 13

A

Palau syndrome

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14
Q

What is the incidence of Patau syndrome

A

1:16000 live births

seen with advancing maternal age

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15
Q

What are effects of Trisomy 13

A

severe intellectual disability, cleft lip/palate, seizures, small jaw, polydactyly, heart defects, brain/spinal cord abnormalities

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16
Q

What is the etiology of Patau syndrome

A

most cases due to true trisomy on chromosome 13.
Some caused by Robertsonian translocation involving chromosomes 13 and 14- part of 13 gets attached to 14, leading to 2 normal copies of 13 plus extra copy attached to another chromosome

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17
Q

What is Cri-du-chat

A

a chromosomal abnormality that occurs due to deletion of short arm of chromosome 5 (partial monosomy) affecting 1:50,000 births

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18
Q

How does Cri-du-chat occur

A

usually due to spontaneous mutation

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19
Q

What are characteristics of cri-du-chat

A

cat like cry due to abnormal larynx development, intellectual disability, wide set eyes, low ears

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20
Q

How can you test for cri-du-chat

A

in utero with CVS

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21
Q

What is Klinefelter’s syndrome

A

when there is an extra X chromosome (47XXY) due to genetic mutation in gametogenesis. Many are lost during first trimester

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22
Q

What are characteristics of Klinefelter’s syndrome

A

affects male physical and cognitive development.

physical traits apparent after puberty; hypogonadism, infertility, gynecomastia, reduced hair

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23
Q

What is Turner syndrome

A

Genetic mutation leading to monosomy of x chromosome (45X) affecting development in females. Not commonly discovered until menstruation doesn’t occur

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24
Q

What are characteristics of Turner syndrome

A

Gonadal dysgenesis, short stature, broad chest, webbed new, amenorrhea, infertility, cardiovascular abnormalities

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25
Q

What is Huntington’s disease

A

An autosomal dominant, neurodegenerative disease/progressive brain disorder due to HD gene on chromosome 4 that codes for protein Huntingtin. It is the only human disorder for complete dominance

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26
Q

What are early signs of Huntington’s disease

A

depression, irritability, poor coordination, trouble learning

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27
Q

At what age is Huntington’s onset

A

usually adult onset, it is latent for 3-5 decades before manifesting as progressive neuronal dysfunction. However, if passed from previous generation, onset is likely to occur sooner

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28
Q

What are fun blown Huntington’s characteristics

A

uncontrolled movements (chorea), emotional problems, loss of thinking ability, changes in personality

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29
Q

What is Huntingtin

A

a CAG nucleotide repeat 36-120 repeats (diseased state) that causes microscopic deposits of protein in neurons

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30
Q

What is the likelihood of survival in Huntington’s

A

After symptoms present, usually 15 years. There is no treatment

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31
Q

How is Huntington’s disease transferred

A

Most cases inherited, some can be spontaneous. If one parent has the disorder, each kid has 50% chance of manifesting. heterozygotes are just as affected as homozygotes (HH, Hh)

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32
Q

What is Alzheimer’s

A

neurodegenerative disease causing the most common form of dementia in older individuals.
Early onset AD (familial) is more rare and late onset AD (sporadic) is more common

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33
Q

What population is at risk for Alzheimer’s

A

usually above age 60. risk increases with age. People with parent, sibling, or child with AD are at increased risk

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34
Q

What is the survival rate of individuals with Alzheimer’s

A

death within 10 years

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35
Q

What is the pathophysiology of Alzheimer’s

A

loss of cholinergic neurons in brain (loss of acetylcholine), PLAQUE and TANGLE formation, brain atrophy, resulting in blocked communication

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36
Q

How is Alzheimer’s transferred

A

several gene mutations can cause a predisposition to AD

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37
Q

What are characteristics of Alzheimer’s

A

progressive mental deterioration, memory loss, confusion, disorientation

38
Q

What is unique about Familial Alzheimer’s

A

symptoms start before 65.
accounts for less than 5% of AD cases
Is autosomal dominant; 50% chance of developing if a parent has it

39
Q

What is the etiology of Familial AD

A

mutation on chromosomes 1, 14, or 21 inducing a “sticky” protein that forms clumps in the brain

40
Q

What is the etiology of Sporadic AD

A

Chromosome 19 apolipoprotein (APOE) gene shows increased risk. But not everyone carrying the gene develops the disease

41
Q

What is unique about Sporadic AD

A

develops after age 65 and accounts for most cases of AD.

Definitive diagnosis is autopsy plaques and tangles

42
Q

What are clinical manifestations of hereditary breast and ovarian cancer syndrome

A

Early age breast cancer ( before 50), FH of both beast and ovarian cancer, increased bilateral cancers, increased development of both cancers, increased incidence of prostate cancer, male breast cancer

43
Q

What are risk factors for HBOCS

A

gender, age, family history

44
Q

How is HBOCS transferred

A

up to 10% caused by known predisposing genetic factors. If a pt has one mutated copy of either susceptibility gene (tumor suppressors BRCA-1, BRCA-2), their risk goes up. But, not all those with mutations on either BRCA gene develop cancer

45
Q

How does a BRCA-1 gene mutation affect HBOCS

A

BRCA-1 is on chromosome 17.
mutation inherited in autosomal dominant manner.
not all families with this gene get hereditary breast cancer

46
Q

How does BRCA-2 gene mutation affect HBOCS

A

BRCA2 is on chromosome 13.
mutation inherited in autosomal dominant manner.
Associated with male breast cancer, ovarian cancer, prostate cancer, and pancreatic cancer

47
Q

How can you test for HBOCS

A

genetically test affected individual first.

Identify whether BRCA1 or BRCA2 could be responsible for the cancer

48
Q

What does colorectal cancer result from

A

interaction of genetic and environmental factors
genetic predisposition is main risk factor for a small portion of people.
Poor diet, smoking, lack of exercise are stronger risk factors

49
Q

How is colorectal cancer transferred

A

mostly from sporadic mutations that occur randomly. Some can occur from familial inheritance

50
Q

What are the two types of colorectal cancer

A

Familial adenomatous polyposis (FAP)- patterns within family without identifying a specific mutation. due to chance, shared exposure to carcinogen, or gene/environmental risk factors
Hereditary nonpolyposis colorectal cancer (HNPCC)-

51
Q

What type of genetic mutation is familial adenomatous polyposis

A 
autosomal dominant (50% chance of passing to kids) with mutation in APC gene (adenomatous polyposis coli), a tumor suppressor gene on chromosome 5
Less than 1% of colorectal cancers
52
Q

How does FAP present

A

hundreds to thousands of polyps in colon, begin in adolescence.
Cancer develops in 20’s.
risk of developing cancer is near 100% before 50.
Polyp to cancer, 10 years

53
Q

What is the recommended diagnosis and treatment of FAP

A

offer genetic counseling and testing after colonoscopy.
Kids of FAP patient should have genetic testing by 10.
Total colectomy recommended before age 20

54
Q

What is Hereditary nonpolyposis colorectal cancer

A

Lynch syndrome.
Autosomal dominant disease that accounts for 2-3% of colorectal cancers, occurring due to mutation of many genes that code for DNA repair

55
Q

How is HNPCC different than FAP

A

more rapid transition from adenoma to cancer than FAP.
Cancers occur earlier, usually 30’s and 40’s.
small number to no polyps present in HNPCC

56
Q

What is HNPCC associated with

A

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

Associated with formation of other cancers- uterus, ovaries, stomach, urinary tract, small bowel, bile ducts

57
Q

What should happen if genetic testing reveals HNPCC gene mutation

A

regular colonoscopy starting at 25, or 5 years younger than age of diagnosis of youngest affected family member.
Upper endoscopy every 2 years for gastric cancer screening.
Screen for endometrial and ovarian cancer at 25-35

58
Q

What is the etiology of Chronic Myelogenous Leukemia

A

translocation between chromosomes 9 and 22 (philadelphia chromosome) causing a myeloproliferative disorder (blood cancer in red/white cells)

59
Q

What is the function of Philadelphia chromosome

A

Chromosome 22- produces a protein that codes for enzyme that causes too many stem cells to develop into WBC

60
Q

What is the pathophysiology of Chronic myelogenous leukemia

A

increased production of abnormal, nonfunctional WBC that end up taking up bone marrow space meant for healthy WBC, RBC and platelets

61
Q

What is the clinical presentation of chronic myelogenous leukemia

A

insidious onset, slow progression over months-years of infections, anemia, bleeding
fever, night sweats, fatigue.

62
Q

How do you diagnose chronic myelogenous leukemia

A

bone marrow aspiration for karyotype

63
Q

What is hemophilia

A

a bleeding disorder caused by mutations in genes that code for coagulation proteins (F8 or F9 genes on X chromosome)

64
Q

What do mutations of F8 and F9 cause

A

F8 causes factor VIII deficiency, resulting in hemophilia A (more common)
F9 causes factor IX deficiency, resulting in hemophilia B (christmas disease, less common)

65
Q

What is the pattern of inheritance of Hemophilia

A

X-linked recessive pattern, so most affected individuals are men

66
Q

What are clinical manifestations of Hemophilia

A

HEMARTHROSES (spontaneous bleeding into a joint), bleeding into muscles and other soft tissues, prolonged bleeding or oozing of blood after injury/surgery

67
Q

What is the pathophysiology of Sickle Cell Disease

A

Atypical hemoglobin S molecules causing RBC to be crescent shaped and breakdown prematurely
Mutation is on HBB gene

68
Q

What are clinical manifestations of sickle cell disease

A

anemia, infections, episodic pain due to destruction and infarct caused by sickle shaped cells getting stuck.
SOB, fatigue, delayed growth

69
Q

What type of disease is sickle cell disease

A

autosomal recessive
most common in people with ancestors from Greece, Africa, Turkey, Italy, Arabian peninsula, India, South America, Central America, Caribbean

70
Q

What is the pattern of inheritance of Cystic Fibrosis

A

autosomal recessive, two copies of mutated gene are needed for disease expression

71
Q

What is the etiology of Cystic fibrosis

A

mutation on CFTR gene (cystic fibrosis transmembrane conductance regulator)- causes disruption of chloride and water transport, and disruption in water balance in secretions

72
Q

What does CFTR code for

A

CFTR codes for protein that regulates chloride channels in epithelial cells

73
Q

What are clinical manifestations of Cystic Fibrosis

A

thick, sticky mucous obstructing airways in lungs and pancreatic ducts.
Difficulty breathing, nutrient digestion difficulties (pancreatic enzymes can’t reach intestine), failure to thrive, poor growth rate, MECONIUM ILEUS (thick fecal waste in infants due to intestinal obstruction).
Can also affect GU tract, hepatobiliary system, and exocrine glands

74
Q

What can CF lead to

A

pulmonary disease because pulmonary system can’t defend against pathogens well.
Sinusitis, bronchitis
Nasal polyps, nose bleeds, chronic sinus infections in kids
Thick mucous in lower airways cause obstruction

75
Q

What are the most common organisms causing pulmonary disease in Cystic Fibrosis

A

S. Aureus, P. aeruginosa, Aspergireis (not the most common organisms for all respiratory diseases)

76
Q

How can you diagnose Cystic Fibrosis

A

sweat chloride test (elevated chloride in CF). If positive, must confirm with genetic testing

77
Q

What is Cystic Fibrosis

A

the most common genetic disease in white US population.
1:3500 white newborns born with disease
1:25 carrier incidence
most are diagnosed by age 1

78
Q

What is the mode of inheritance of Marfan Syndrome

A

Autosomal dominant

resulting from inherited or new mutation of FBN1 (fibrillar-1 gene)

79
Q

What does Marfan Syndrome cause

A

defects in connective tissue affecting bones, ligaments, muscles, blood vessels, heart valves

80
Q

What are 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, hyper flexible joints, chest deformities

81
Q

What are Key primary features of Marfan Syndrome

A

dislocated lens of eye causing vision problems

aortic aneurysm/dissection

82
Q

What are the major causes of morbidity and mortality

A

heart defects

Mitral valve prolapse and aortic valve regurgitation that cause SOB, fatigue, palpitations

83
Q

What should Marfan patients avoid

A

contact sports, caffeine, decongestants due to increased stress on CV system

84
Q

What is the mode of inheritance of Neurofibromatosis Type I

A

von Recklinghausen disease (NF-1 most common)
Autosomal dominant
Due to mutation on NF1 gene on chromosome 17 (tumor suppressor gene), resulting in growth of neurofibromas (benign tumors on nerves of skin and brain) and change in skin pigmentation (darker)

85
Q

What are diagnostic features of Neurofibromatosis I

A 
CAFE-AU-LAIT
CROWE SIGN (axillary/inguinal freckling) 
Lisch nodules in iris
2+ neurofibromas
optic glioma
1st degree relative with NF1
86
Q

What is the pathophysiology of Polycystic Kidney Disease

A

clusters of fluid filled sacs develop in kidneys affecting ability to filter blood properly. Kidneys become enlarged and fail

87
Q

What are clinical manifestations of PKD

A 
HTN
back pain
hematuria
UTI/ renal stones
Also, liver cysts, heart valve abnormalities, increased risk for aortic or brain aneurysm
88
Q

What are the two forms of PKD

A

Autosomal dominant: Sx start as adult. inherited 90% of time. 1:1000 PKD1 and PKD2 genes
Autosomal recessive: rare, lethal in early life. 1:30,000. PKHD1 gene

89
Q

What are congenital abnormalities caused by

A

variety of biological, chemical, and physical agents.

Contributors are mutant genes, chromosomal defects, and multifactorial components

90
Q

What is the biggest cause of birth defects

A

unknown etiology.

Apps 10% of all newborns have some birth defect, from minor biochemical problem, to severe physical deformity

Foundations (4 decks)

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