Genetics and Chromosomal Flashcards

1
Q

risk of autosomal dominant disease for child with 1 affected parent

A

50% risk

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2
Q

risk of autosomal recessive disease for child with 1 affected parent

A

25% risk

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3
Q

risk of X-linked recessive disease for child when mother is carrier

A

50% of her daughters can be carriers
50% of her sons can be affected
50% of her offspring can be normal
25% of her offspring will manifest the disease

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4
Q

Etiology of Down Syndrome

A

trisomy of chromosome 21; maternal non-disjunction; associated with advanced maternal age

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5
Q

Down Syndrome Prenatal Screening Tests

A

quad screen: alpha fetoprotein, estriol, Hcg and inhibin A

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6
Q

Down syndrome hands and feet

A

hand: clindoactyly, single flexion crease (Simian crease), short broad hands, shortened 5th phalynx
feet: wide spaced 1st/2nd toes (“sandle toes”)

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7
Q

Facial characteristics of Down Syndrome

A

flattened face, epicanthal folds, big tongue (macroglossia), small chin (micrognathia), low set ears

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8
Q

Newborn with possible Down Syndrome must have ______ done before discharge.

A

ECHO

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9
Q

Neuro effects of Downs

A

mental retardation (mild/mod), seizures (5-10%), early Alzheimer’s and dementia (30-40yo)

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10
Q

Results of prenatal quad screen in Downs

A

Low Alpha Feto Protein
Low Unconjugated estriol
Elevated hCG
Elevated Inhibin A

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11
Q

Cardiac effects of Downs

A

50% with cardiac anomalies (ASD most common); need ECHO!!!

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12
Q

HEENT effects of Downs

A

Hearing loss, ET dysfunction (recurrent otitis media, sinusitis), early cataracts and glaucoma, Brushfield spots

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13
Q

trisomy 18 is called __________ syndrome.

A

Edwards

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14
Q

Phenotypic features of trisomy 18

A

rocker-bottom feet, clenched hand w/ overlapping fingers, hypotonia, micropthalmia (small eyes), micrognathia

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15
Q

Prognosis of Edwards Syndrome

A

only 5% live past 1 year

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16
Q

Trisomy 13 is called _________ Syndrome

17
Q

Features of Patau Syndrome

A

Polydactyly
Aplasia Cutis (missing patches of skin)
Cryptorchidism (no testes in scrotum)
Equinovarus deformities

18
Q

Prognosis of trisomy 13

A

95% die by 6 months of age due to apneic spells

19
Q

XXY (extra X chromosome) called _____.

A

Klinefelter Syndrome

20
Q

Etiology of extra X chromosome

A

Non-disjunction in either the sperm or egg

Increased with advanced maternal age

21
Q

Klinefelter most common genetic cause of _____ in men.

A

infertility

22
Q

Signs of XXY

A

present as tall, thin, socially awkward adolescent male with mild mental delays

testosterone deficiency, small penis, hypogonadism, scant pubic hair, gynecomastia

23
Q

Young female comes in with absence of menses. What to do?

A

Pregnancy test

r/o Turner Syndrome

24
Q

Most common cause of inherited mental retardation in males is ______.

A

Fragile X syndrome

25
Monosomy X or XO karyotype is _________.
Turner Syndrome
26
PE with XO karyotype
female, short stature, webbed neck, broad chest with widely spaced nipples, congenital lymphedema
27
Turner syndrome co-existing anomalies
``` congenital heart defect horseshoe kidneys ovarian streaks (sterile, amenorrheic) ```
28
Can Turner Syndrome patients have children?
Yes; still have uterus (IVF and hormonal therapy)
29
Inheritance pattern of Fragile X
X-linked dominant; mother gives to all sons
30
Physical findings of Fragile X
Elongated Face Wide Protruding Ears Flattened Nasal Bridge Macro-orchidism
31
Developmental problems of Fragile X
- Mild autistic-like behavior - ADHD - Depressed affect, anxiety - Mental retardation thats worse with age - Aggressive tendencies
32
Tx for Fragile X
- Meds for ADD and behaviors | - Genetic counseling
33
Prader-Willi syndrome etiology
Gene deletions of parental chromosome 15
34
Characteristics of Prader-Willi
- SGA, hypogonadism, hypotonia, poor feeding as infant, small hands & feet, almond-shaped eyes, strabismus, short stature - developmental delay, temper tantrums - voracious appetite and obesity in childhood
35
Common characteristics of Angelman syndrome
Severe mental retardation, marked developmental delay, limited language skills, paroxysmal laughter, tongue thrusting Prognathism (jaw protrudes), seizures, and abnormal gait & posturing (“happy puppet”)
36
Dx testing if chromosomal abnormality suspected
karyotype and fluorescent in situ hybridization (FISH)
37
Two most common chromosomal abnormalities of live births
1. Down syndrome (1/750) | 2. Klinefelter syndrome - XXY (1/800)
38
How are most chromosomal abnormalities managed?
supportive care, environmental and educational programs, physical therapy, etc.