Genetics and Chromosomal

Question 1

risk of autosomal dominant disease for child with 1 affected parent

Answer 1

50% risk

Question 2

risk of autosomal recessive disease for child with 1 affected parent

Answer 2

25% risk

Question 3

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

Answer 3

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

Question 4

Etiology of Down Syndrome

Answer 4

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

Question 5

Down Syndrome Prenatal Screening Tests

Answer 5

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

Question 6

Down syndrome hands and feet

Answer 6

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

Question 7

Facial characteristics of Down Syndrome

Answer 7

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

Question 8

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

Answer 8

ECHO

Question 9

Neuro effects of Downs

Answer 9

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

Question 10

Results of prenatal quad screen in Downs

Answer 10

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

Question 11

Cardiac effects of Downs

Answer 11

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

Question 12

HEENT effects of Downs

Answer 12

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

Question 13

trisomy 18 is called __________ syndrome.

Answer 13

Edwards

Question 14

Phenotypic features of trisomy 18

Answer 14

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

Question 15

Prognosis of Edwards Syndrome

Answer 15

only 5% live past 1 year

Question 16

Trisomy 13 is called _________ Syndrome

Answer 16

Patau

Question 17

Features of Patau Syndrome

Answer 17

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

Question 18

Prognosis of trisomy 13

Answer 18

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

Question 19

XXY (extra X chromosome) called _____.

Answer 19

Klinefelter Syndrome

Question 20

Etiology of extra X chromosome

Answer 20

Non-disjunction in either the sperm or egg

Increased with advanced maternal age

Question 21

Klinefelter most common genetic cause of _____ in men.

Answer 21

infertility

Question 22

Signs of XXY

Answer 22

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

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

Question 23

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

Answer 23

Pregnancy test

r/o Turner Syndrome

Question 24

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

Answer 24

Fragile X syndrome

Question 25

Monosomy X or XO karyotype is _________.

Answer 25

Turner Syndrome

Question 26

PE with XO karyotype

Answer 26

female, short stature, webbed neck, broad chest with widely spaced nipples, congenital lymphedema

Question 27

Turner syndrome co-existing anomalies

Answer 27

congenital heart defect
horseshoe kidneys
ovarian streaks (sterile, amenorrheic)

Question 28

Can Turner Syndrome patients have children?

Answer 28

Yes; still have uterus (IVF and hormonal therapy)

Question 29

Inheritance pattern of Fragile X

Answer 29

X-linked dominant; mother gives to all sons

Question 30

Physical findings of Fragile X

Answer 30

Elongated Face
Wide Protruding Ears
Flattened Nasal Bridge
Macro-orchidism

Question 31

Developmental problems of Fragile X

Answer 31

• Mild autistic-like behavior
• ADHD
• Depressed affect, anxiety
• Mental retardation thats worse with age
• Aggressive tendencies

Question 32

Tx for Fragile X

Answer 32

• Meds for ADD and behaviors

- Genetic counseling

Question 33

Prader-Willi syndrome etiology

Answer 33

Gene deletions of parental chromosome 15

Question 34

Characteristics of Prader-Willi

Answer 34

• 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

Question 35

Common characteristics of Angelman syndrome

Answer 35

Severe mental retardation, marked developmental delay, limited language skills, paroxysmal laughter, tongue thrusting

Prognathism (jaw protrudes), seizures, and abnormal gait & posturing (“happy puppet”)

Question 36

Dx testing if chromosomal abnormality suspected

Answer 36

karyotype and fluorescent in situ hybridization (FISH)

Question 37

Two most common chromosomal abnormalities of live births

Answer 37

1. Down syndrome (1/750)

2. Klinefelter syndrome - XXY (1/800)

Question 38

How are most chromosomal abnormalities managed?

Answer 38

supportive care, environmental and educational programs, physical therapy, etc.