Down Syndrome - Elias L1 Flashcards
What is the chromosomal error that cases trisomy 21 and what increases the risk of this happening?
Error in nondisjunction
Maternal age ≥35-40
What are the three genotypes associated with DS and what percentages of pts present with each?
Trisomy 21 95%
Unbalanced Translocation 3-4% (e.g. t(21,14))
Mosaic Tri 21 1-2% milder presentation usually
First trimester screening for Trisomy 21?
Ultrasond measrement of nuchal folds (extra folds = bad)
Beta-hCG + PAPP-A
(human chorionic gonadotropin, pregnancy-associated plasma protein A)
2nd trimester trisomy 21 screening?
Detection rate in 2nd trimester?
Quad Screen beta-hCG AFP (alpha-fetoprotein) unconjugated estriol inhibin level
Detection rate at 2nd trimester = 95%
Estimated incidence of trisomy 21?
1 in 700
At what maternal age is the risk become high?
35 and up the curve shoots up.
Recurrance risk?
1/100 + maternal age risk (see graph)
age 40 risk is 1/100
—> recurrance risk is 1/50
List some common physical finding of a DS infant.
- growth parameters usually normal
- midfacial hypoplasia
- upslanting palpebral fisures, epicanthal folds
- small ears
- tounge seems large but really the oral compartment is small
- low muscle tone (hypotonia), double jointed (increased joint mobility)
- short fingers, transverse palmer crease, 5th finger incurving (clinodactyly), increased space btwn 1st & 2nd toes
- Eustation tubes too small -> ear infections
Incidence of cardiac issues in DS pts?
Some common cardiac issues?
50% of DS pts have cardiac issues
Wide range of cardiac defects:
Atrioventriclar Canal (common, needs surgical repair)
hole btwn atria
hole btwn ventricles
Incidence of GI tract issues in DS pts?
3 most common ones?
10 - 15% of infants have GI tract structural anomalies
Esophageal atresia
Dodenal atresia
Hirschsprng’s Disease (sympathetics non-functional in lower 1/3 of bowel, constipation)
What are the functional GI issues in DS pts?
feeding problems - very common
constipation - extremely common due to hyptonia
GERD - very common
Celiac Disease (screen with TTG +IgA)
What are the opthalmologic problems in DS pts?
blocked tear ducts myopia (near sightedness) strabismus (lazy eye) nystagmus cataracts - congenital or dev. over time
What fraction of DS pts have ear, nose and throat problems?
Common ENT problems?
2/3
chronic ear infections (small eustatian tubes)
deafness (both conductive (fluid) and sensorineural)
chronic nasal congestion
enlarged tonsils & adnoids = Obstructive Sleep Apnea, also related to obesity
What are some common endocrine disorders in DS pts?
Thyroid = most common endocrine problem seen; usually hypothyroidism but also Grave's disease Insulin Dependent Diabetes (type 1) Alopecia Areata (hair falls out in patches) Reduced fertility
Joint issues in DS pts?
hips dislocation
joint subluxation
**atlantoaxial subluxation - rare but bad = high level cervical paralysis