Down Syndrome Flashcards
Consanguinity
Genetically related individuals having kids
- increased risk of genetic mutations and having “abnormal” kids
Pedigrees
drawing and reading a pedigree can be important for taking detailed family histories for possible genetic syndromes
DDx for hypotonia in newborn
- Down Syndrome
- Benign neonatal hypotonia
- Zellweger Syndrome
- Family resemblance
Common features of down syndrome
- Flat facies
- Upslanting palpebral fissures
- Prominent epicanthal folds
- Redundant neck skin
- Small ears
- Hypotonia
Trisomy 21
- 47 (XY)+21
- Unbalanced chromosome translocation –> extra 21 material
- Mosaicism for trisomy 21 cell line (cannot 100% rule this out with chromosome testing, but likely not the case)
Diagnostic testing for trisomy 21
lymphocyte karyotyping = gold standard
FISH testing available but not replacing karyotyping
Risk of having a baby with down syndrome
Risk higher per pregnancy for women >35 y.o.
Majority of infants with down syndrome born to women
Down Syndrome and Hypothyroidism
Down kids have increased risk of having hypothyroidism
Sharing difficult news
- don’t information overload
- multiple appointments may be best to allow time to process info and generate questions
Indications for chromosome studies in kids
- Down Syndrome
- Unrecognized malformation
- Mental retardation
- Unusual findings
- Tumors
- Multiple pregnancy losses
F/U in kids with down
- Annual thyroid screening
- Vision and hearing screening
- CBC in 1st month of leukemoid disorders
- Pediatric cardiologist - congenital defects
- Annual Hgb and Hct - iron deficiency anemia
- Early intervention - therapy
Down Syndrome
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
Prenatal testing/screening for down
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
Fragile X Syndrome
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
Turner Syndrome
- 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
Kleinfelter Syndrome
boys normal at birth until puberty/adulthood
- infertility and testicular atrophy
- eunuchoid body habitus, gynecomastia, IQ varies
- 47 XYY, 47 XXX
Trisomy 13 (patau)
microopthalmia, microcephaly, polydactyly, cleft lip and palate, cardiac and renal defects, IQ defects
Trisomy 18 (edwards)
IQ defects, prominent occiput, micrognathia, low ears, overlapping fingers, heart defects, short neck, rocker-bottom feet
Short stature
VERY common in down syndrome kids –> due to hypothyroidism
- use Down Syndrome growth charts
Encourage Parents to be advocates
All kids with intellectual disabilities should have individualized education plans
