Down Syndrome

Question 1

Consanguinity

Answer 1

Genetically related individuals having kids

- increased risk of genetic mutations and having “abnormal” kids

Question 2

Pedigrees

Answer 2

drawing and reading a pedigree can be important for taking detailed family histories for possible genetic syndromes

Question 3

DDx for hypotonia in newborn

Answer 3

1. Down Syndrome
2. Benign neonatal hypotonia
3. Zellweger Syndrome
4. Family resemblance

Question 4

Common features of down syndrome

Answer 4

1. Flat facies
2. Upslanting palpebral fissures
3. Prominent epicanthal folds
4. Redundant neck skin
5. Small ears
6. Hypotonia

Question 5

Trisomy 21

Answer 5

1. 47 (XY)+21
2. Unbalanced chromosome translocation –> extra 21 material
3. Mosaicism for trisomy 21 cell line (cannot 100% rule this out with chromosome testing, but likely not the case)

Question 6

Diagnostic testing for trisomy 21

Answer 6

lymphocyte karyotyping = gold standard

FISH testing available but not replacing karyotyping

Question 7

Risk of having a baby with down syndrome

Answer 7

Risk higher per pregnancy for women >35 y.o.

Majority of infants with down syndrome born to women

Question 8

Down Syndrome and Hypothyroidism

Answer 8

Down kids have increased risk of having hypothyroidism

Question 9

Sharing difficult news

Answer 9

• don’t information overload

- multiple appointments may be best to allow time to process info and generate questions

Question 10

Indications for chromosome studies in kids

Answer 10

1. Down Syndrome
2. Unrecognized malformation
3. Mental retardation
4. Unusual findings
5. Tumors
6. Multiple pregnancy losses

Question 11

F/U in kids with down

Answer 11

1. Annual thyroid screening
2. Vision and hearing screening
3. CBC in 1st month of leukemoid disorders
4. Pediatric cardiologist - congenital defects
5. Annual Hgb and Hct - iron deficiency anemia
6. Early intervention - therapy

Question 12

Down Syndrome

Answer 12

Caused by presence of extra chromosome 21 in each somatic cell

• can occur to anyone at any age but moms >35 have greatest risk
• 1/700 births

Question 13

Prenatal testing/screening for down

Answer 13

Chromosome analysis of amniotic fluid and chorionic villus sampling = direct diagnostic tests for down (cells are fetal origin)
Maternal serum screen and US - can give an estimate or give risks of fetus having down but the serum isn’t of fetal origin so not diagnostic

Question 14

Fragile X Syndrome

Answer 14

X-linked disease caused by inheritance of abnormal number of CGG repeats on FMR1 gene (>200 repeats)

• long face with large mandible
• large, prominent ears
• large testicles

Question 15

Turner Syndrome

Answer 15

• most likely to be associated with physical differences at birth
  LYMPHEDEMA: webbed neck, low ears, edematous hands and feet, shield chest, convex nails
• others: coarctation of aorta, short stature, normal IQ

Question 16

Kleinfelter Syndrome

Answer 16

boys normal at birth until puberty/adulthood

• infertility and testicular atrophy
• eunuchoid body habitus, gynecomastia, IQ varies
• 47 XYY, 47 XXX

Question 17

Trisomy 13 (patau)

Answer 17

microopthalmia, microcephaly, polydactyly, cleft lip and palate, cardiac and renal defects, IQ defects

Question 18

Trisomy 18 (edwards)

Answer 18

IQ defects, prominent occiput, micrognathia, low ears, overlapping fingers, heart defects, short neck, rocker-bottom feet

Question 19

Short stature

Answer 19

VERY common in down syndrome kids –> due to hypothyroidism

- use Down Syndrome growth charts

Question 20

Encourage Parents to be advocates

Answer 20

All kids with intellectual disabilities should have individualized education plans