Down Syndrome

Question 1

Causes of Down Syndrome (DS)- name 3 of 5

Answer 1

Trisomy 21, unbalanced translocation between chromsome 21 and another acrocentric chromosome, mosaic Tri 21

Question 2

Prenatal Screening for DS in 1st trimester

Answer 2

detection rate 82-87%; ultrasound measurement of nuchal folds + beta-hCH and PAPP-A (pregnancy-associated plasma protein A)

Question 3

Prenatal Screening for DS in 2nd trimester

Answer 3

quad screen- beta-hCG, AFP (alpha-fetoprotein), unconjugated esriol, and inhibin level; Suspicion of DS based on 1st or second trimester screening can be confirmed by Chromosome analysis via amniocentensis or CVS (chorionic villus sampling)

Question 4

What are three types of trisomies which may be seen in liveborn infants?

Answer 4

Trisomy 13, 18, 21. Birth defects associated with Trisomies 13 and 18 are often life-threatening, and most babies with these diagnoses do not survive to see their first birthday.

Question 5

Physical features of infants with DS

Answer 5

Growth parameters normal, midfacial hypoplasia, upslanting palpebral fissures, epicanthal folds, small ears, large appearing tongue, low muscle tone, increased joint mobility, short fingers, transverse palmar crease, Vth finger incurving (clinodactylyl), increased space between toes 1 and 2.

Question 6

Cardiac Issues in DS

Answer 6

Cardiac issues; seen in approx 50%; all anomalies present, but atrioventricular canal is common to DS.

Question 7

Gastrointestinal Issues in DS

Answer 7

Gastrointestinal; approx 10-15% wil have esophageal atresia, duodenal atresia, Hirschsprung’s, but many will have feeding prob, constipation, GERD, celiac dz.

Question 8

Ophthalmologic Problems in DS

Answer 8

Ophthalmologic Problems, blocked tear ducts, myopia, lazy eye, nystagmus, cataracts.

Question 9

Ears, Nose, and Throat Problems in DS

Answer 9

Chronic ear infections, deafness, chronic nasal congestion, enlarged tonsilsand adenoids (resulting in obstructive apnea)

Question 10

Endocrine Problems in DS

Answer 10

Thyroid dz (most commonly hypothyroidism), insulin dependent diabetes, alopecia areata (patches of baldness), reduced fertility but with normal puberty

Question 11

Orthopedic Problems in DS

Answer 11

Hips, joint subluxation, atlantoaxial subluxation

Question 12

Hematologic Issues in DS

Answer 12

Myeloproliferative disorder in the newborn (blood cells growing abnormally in bone marrow), increased risk of leukemia, iron deficiency anemia

Question 13

Developmental Issues in DS

Answer 13

Hypotonia (affects gross motor development), spectrum of intellectual disability, speech problems (importance of sign language)

Question 14

Neurologic Problems in DS

Answer 14

Hypotonia- spectrum from mild-severe, seizures, especially infantile spasms

Question 15

Psychiatric Issues in DS

Answer 15

Depression, early Alzheimer’s, Autism- 1/10 patients with DS

Question 16

How can isochromosomal rearrangement result in Down syndrome?

Answer 16

21q21q translocation

Gametes with 21q21q chromosome is fertilized with normal gamete with 21 acrosome