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Foundations > Genetic Diseases & Syndromes > Flashcards

Genetic Diseases & Syndromes Flashcards

1
Q

Down syndrome

A
  • Most common chromosomal abnormality in live births
  • Increased incidence w/ advancing maternal age
  • Age 35 1:400
  • Age 45 1:35
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2
Q

Down syndrome prenatal testing

A
  • Quad screen

- Nuchal translucency

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3
Q

Cause of Down syndrome

A
  • Gamete has 2 copies of chromosome 21
  • Trisomy 21 is cause of 95%
  • Roberstonian translocation = 4%
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4
Q

Down syndrome prevalance

A

1:500 pregnancies

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5
Q

Down syndrome characteristics

A
  • Intellectual disability
  • Characteristic facial appearance
  • 40% cardiac defects
  • 75% hearing loss
  • > 50% visual problems
  • 7% have GI defects
  • Increased social skills
  • 1/2 develop Alzheimer disease
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6
Q

Edwards Syndrome

A
  • Trisomy 18
  • 2nd most common autosomal trisomy
  • IUGR
  • Many die before birth or in first month
  • Increased risk w/ advanced maternal age
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7
Q

Edwards syndrome characteristics

A
  • Kidney, heart, GI defects
  • Developmental delay
  • Club foot (Rocker bottom feet)
  • Low set ears, small jaw
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8
Q

Edwards syndrome prevalence

A

1: 5000 live born infants
- Highly lethal in-utero (85% lost btwn 10 wks gestation & term)
- 50% die in 1st week of life
- 2% have 1 year survival

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9
Q

Patau syndrome

A
  • Trisomy 13

- Increased risk w/ advanced maternal age

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10
Q

Patau syndrome prevalence

A

1: 16000 live births

- Many die within 1st days or weeks of life

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11
Q

Patau syndrome characteristics

A
  • Severe intellectual disability
  • Cleft lip or palate
  • Seizures
  • Small jaw
  • Polydactyly
  • Heart, brain/spinal defects
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12
Q

Patau syndrome etiology

A
  • Most cases = 3 copies of chromosome 13

- Some due to Robertsonian translocation involving chromosome 13 & 14

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13
Q

Cri-du-chat syndrome

A
  • Deletion of part of short arm of chromosome 5

- Partial monosomy (only a portion of a chromosome has 1 copy instead of 2)

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14
Q

Cri-du-chat etiology

A
  • Most cases = spontaneously
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15
Q

Cri-du-chat characteristics

A
  • Cat like cry due to abnormal larynx
  • Intellectual disability
  • Wide set eyes, low ears
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16
Q

Cri-du-chat prevalence & how is it detected?

A

1: 50,000 births

- Detected in utero w/ CVS

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17
Q

Klinefelter’s syndrome

A
  • Extra X chromosome, 47XXY
  • Occurs during gametogenesis
  • Accounts for 1st trimester losses
  • Most common sex chromosome aneuploidy in males
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18
Q

Klinefelter’s characteristics

A
  • Affects male physical & cognitive development
  • Physical traits become more apparent after puberty
  • Hypogonadism, infertility
  • Gynecomastia, reduced hair
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19
Q

Turner syndrome

A
  • 45X
  • Affects development in females
  • Monosomy
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20
Q

Turner syndrome characteristics

A
  • Gonadal dysgenesis (non-functional ovaries)
  • Short stature
  • Broad chest
  • Webbed neck
  • Amenorrhea
  • Infertility
  • Cardiovascular defects
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21
Q

Huntington’s disease

A
  • Neurodegenerative disease (progressive brain disorder)

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

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22
Q

Huntington’s disease characteristics

A
  • Uncontrolled movements
  • Emotional problems
  • Loss of thinking ability
  • Changes in personality
  • Involuntary jerking movements: chorea
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23
Q

Early signs of Huntington’s

A
  • Depression
  • Irritability
  • Poor coordination
  • Trouble learning
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24
Q

Huntington’s etiology

A
  • HD gene on chromosome 4 that encodes for huntington
  • Autosomal dominant
  • Average time from sx onset to death = 15 yrs
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25
Q

Alzheimers syndrome

A
  • Neurodegenerative disease
  • Most common form of dementia in elderly
  • Death usually occurs within 10 yrs of dx
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26
Q

Causes of dementia

A
  • 65% Alzheimers

- 35% vascular

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27
Q

Alzheimers population

A

Begins after age 60 (risk increases w/ age)

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28
Q

Alzheimers pathophysiology

A
  • Loss of cholinergic neurons in brain
  • Formation of plaques/tangles
  • Atrophy of brain
  • Resultant effect - blocked communication
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29
Q

Alzheimers mode of inheritance

A

Several gene mutations cause predisposition

- 2 forms of genes have been identified: familial (early onset); sporadic (late onset)

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30
Q

Alzheimers clinical manifestations

A
  • Progressive mental deterioration (memory loss, confusion, disorientation)
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31
Q

Familial Alzheimers

A
  • Many members of multiple generations affected
  • Sx start before age 65
  • Mutations on chromosomes 1, 14, or 21 (forms “sticky” protein that forms clumps in brain)
  • Rare, <5%
  • Autosomal dominant
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32
Q

Sporadic Alzheimers

A
  • Develops after 65
  • Accounts for most cases of AD
  • One gene increases risk: Chromosome 19 apolipoprotein E (APOE)
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33
Q

Definitive dx of sporadic Alzheimers

A

Autopsy- plaques, tangles

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34
Q

Risk factors of breast/ovarian cancer

A
  • Gender
  • Age
  • Family hx
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35
Q

Mode of inheritance of breast/ovarian cancer

A

Up to 10% are caused by predisposing genetic factors

36
Q

Clinical manifestations of breast/ovarian cancer

A
  • Early age of breast cancer onset (<50)
  • Family hx of both breast and ovarian cancer
  • Increased bilateral cancers
  • Increased development of both cancers in the same person
  • Increased incidence of prostate cancer in family
  • Male breast cancer
37
Q

2 major cancer susceptibility genes

A

BRCA1, BRCA2

- Tumor suppressor genes

38
Q

BRCA1

A
  • On chromosome 17

- Autosomal dominant

39
Q

BRCA2

A
  • On chromosome 13

- Autosomal dominant

40
Q

Genetic testing

A
  • Test individual who is affected first
41
Q

Colorectal cancer

A
  • May occur sporadically (most) or familial

- Results from interaction of both genetic and environmental factors (diet, lack of exercise, smoking, obesity)

42
Q

What is considered a positive family hx?

A

1 of more people in family w/ colorectal cancer or premalignant polyps
- May be due to: chance, shared exposure to a carcinogen or diet/lifestyle factors, combination of gene mutations and environmental risk factors)

43
Q

Familial adenomatous polyposis (FAP)

A
  • < 1% of colorectal cancers

- Autosomal dominant (50% chance of passing to offspring)

44
Q

FAP genetic mutation

A

Mutation in APC gene

  • Tumor suppressor on chromosome 5
  • 100s/1000s of polyps developing in adolescents
  • Cancer develops in 20s
  • Risk of cancer = 100% (before 50yo)
  • Polyp –> cancer = 10+ years
45
Q

Once FAP is dx, what is recommended?

A

Total colectomy before age 20

46
Q

Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

A
  • aka. Lynch Syndrome
  • 2-3% of colorectal cancers
  • Autosomal dominant
  • More rapid transition from adenoma to cancer than FAP
  • Cancer occurs in 30s & 40s
47
Q

HNPCC genetic mutation

A

In one of many genes that code for DNA repair

48
Q

Nonpolyposis refers to what?

A

Colorectal cancer that can occur when a small # or no polyps are present

  • 50% chance of cancer in women
  • 70% in men
  • Associated w/ other cancers
49
Q

If genetic testing reveals HNPCC

A
  • Regular colonoscopy starting at age 25 in relatives (or 5 yrs younger than age of dx of family member)
  • Upper endoscopy every 2 yrs to screen for gastric cancer
  • Screening for endometrial & ovarian cancer in women 25-35
50
Q

Chronic myelogenous leukemia

A
  • Myloproliferative disorder
  • Translocation btwn chromosome 9 & 22
  • Philadelphia chromosome (22)
51
Q

Chronic myelogeneous leukemia population

A
  • More common in men

- Median age = 55

52
Q

Philadelphia chromosome (22)

A

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

53
Q

Pathophysiology of CML

A
  • Increased production of abnormal/nonfunctional WBCs

- WBCs take up bone marrow space

54
Q

Clinical presentation of CML

A
  • Insidious onset
  • Slow progression over months to years
  • Anemia, bleeding
  • Fever, night sweats, fatigue
55
Q

CML Dx

A

Bone marrow aspiration for karyotype

56
Q

Hemophilia

A
  • Bleeding disorder caused by mutations in genes that code for coagulation
  • Mutation on F8 & F9 genes on X chromosome
  • X-linked recessive
  • Males are most affected
57
Q

Mutation on F8

A
  • Causes factor VIII deficiency
  • Results in hemophilia A (classic form)
  • More common
58
Q

Mutation on F9

A
  • Causes factor IX deficiency

- Results in hemophilia B (Christmas Disease)

59
Q

Clinical manifestations of hemophilia

A
  • *Hemarthrosis
  • Bleeding into muscles/tissues
  • Prolonged bleeding/oozing after injury or surgery
60
Q

Sickle cell disease

A
  • Atypical hemoglobin molecules (hemoglobin S)
  • Distorts RBC into crescent shape
  • Abnormally shaped RBCs break down prematurely
  • Mutation on HBB gene
61
Q

Sickle cell clinical manifestations

A
  • Anemia
  • Infections
  • Episodic pain
  • SOB
  • Fatigue
  • Delayed growth
62
Q

Sickle cell inheritance

A

Autosomal recessive

63
Q

Sickle cell population

A

Greece, Africa, Turkey, Italy, Arabian Peninsula, India, South America, Central America, Caribbean

64
Q

Cystic fibrosis pattern of inheritance

A

Autosomal recessive

- 2 copies of mutated gene are needed for disease to be expressed

65
Q

Cystic fibrosis genetic mutation

A

Mutation in the CFTR gene

  • CFTR codes for a protein that regulates chloride channels
  • When mutated, a defective protein is made –> disruption of chloride & H2O transport
66
Q

Clinical manifestations of cystic fibrosis

A
  • Thick, sticky mucous obstructing airways in lungs & ducts in pancreas
  • Can affect pancreas, intestines, exocrine glands, hepatobiliary system
67
Q

Cystic fibrosis sx

A
  • Difficulty breathing, infections in lungs
  • Problems w/ 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
68
Q

What is the most common cause of morbidity associated with CF?

A

Pulmonary disease

  • Pulmonary system can’t defend against pathogens –> sinusitis & bronchitis
  • S. aureus, P. aeruginosa, Aspergillus
  • Nasal polyps, nosebleeds, chronic sinus infections
69
Q

Population & incidence of CF

A
  • White population in US
  • 1 in 3500 white newborns
  • Carrier incidence: 1 in 25
70
Q

CF Dx

A
  • Most dx by age 1
  • Sweat chloride test:
    Chloride channel doesn’t allow chloride to be reabsorbed
  • [chloride] in sweat is elevated
71
Q

Marfan syndrome mode of inheritance

A
  • Autosomal dominant
  • An inherited mutation or a new mutation of fibrillin-1 gene (FBN1)
  • Causes defects in CT affecting:
    Bones
    Ligaments
    Muscles
    Blood vessels
    Heart valves
72
Q

Marfan clinical manifestations

A 
Tall stature
Long, thin arms &amp; legs
Arm span wider than body height
Long, narrow face
High arched palate
Overcrowded teeth
Scoliosis
Hyperflexible joints
Chest deformities
73
Q

Marfan primary features

A
  • Dislocated lens of the eye – vision problems

* Aortic aneurysm/dissection

74
Q

Major cause of morbidity/mortality in Marfan syndrome?

A

Heart defects

  • Mitral valve prolapse, aortic valve regurg
  • SOB, fatigue, palpitations
75
Q

Marfan syndrome recommendations

A

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

76
Q

Neurofibromatosis Type 1

A
  • aka. von Recklinghausen
  • Most common type
  • Subcutaneous tumors
77
Q

Neruofibromatosis Type 1 pattern of inheritance

A
  • Autosomal dominant
  • Mutation on NF1 gene on chromosome 17
    (tumor suppressor gene)
  • Results in:
    Growth of neurofibromas
    Changes in skin pigmentation
78
Q

NF - Type 1 manifestations

A
  • Hyperpigmented skin lesions (café-au-lait spots)
  • Lisch nodules in iris
  • Freckles in axillae & groin
79
Q

NF Type 1 dx features

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 before puberty
  • 2 or more neurofibromas
  • Axillary or inguinal freckling (Crowe sign*)
  • Optic glioma
  • 2 or more Lisch nodules
  • 1st degree relative w/ NF1
80
Q

Pathophysiology of PKD

A
  • Clusters of fluid filled sacs develop in kidneys
  • Affects ability to filter blood
  • Kidneys become enlarged & can fail
81
Q

PKD clinical manifestations

A
  • HTN
  • Back pain
  • Hematuria
  • UTIs, kidney stones
82
Q

PKD other associations

A
  • Liver cysts
  • Heart valve abnormalities
  • Increased risk of aortic & brain aneurysms
83
Q

What are the 2 forms of PKD?

A

Autosomal dominant: sx start in adulthood

  • 1 in 1000
  • PKD1 & PKD2 genes
  • Usually inherited (90%)

Autosomal recessive: rare, lethal early in life

  • 1 in 30,000
  • PKHD1 gene
84
Q

What % of newborns have a congenital defect?

A

10%

- Unknown etiology*

85
Q

Teratology

A

Study of abnormal development

  • Teratogens: anything capable of disrupting embryonic or fetal development & producing malformations
  • Critical period for teratogenic effects is 3-16 weeks gestation
  • Timing of exposure determines which systems are affected
86
Q

Newborn screening

A
  • Biochemical analysis
  • Determines whether certain proteins are present or absent
  • Typically autosomal recessive conditions
  • “Inborn errors of metabolism”: Inherited defect in 1 or more enzymes
87
Q

When is the 1st & 2nd test performed in newborn screening?

A

1st test: 24-36 hrs (heal stick)

2nd test: @ 1st office visit, 5-10 days

Foundations (9 decks)

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