Down syndrome Flashcards
What is an autosome?
autosome is any chromosome that is not a sex-determining chromosome
NOTE: numerical disorders are more likely in the sex chromosomes.
Etiology of DS?
Approximately 95% caused by nondisjunction or an error in cell division during meiosis resulting in a trisomy of chromosome 21.
A rare seen in offspring of those with a Robertsonian translocation involving long arm of CHR 21q
Inc risk with increase in maternal age
How might maternal age influence risk of down syndrome from trisomy 21?
Inc risk of non disjunction. R/t the aging of the oocyte. Egg (oocytes) are there from birth, higher risk of damage of environmental agents such as drugs, chemicals, and radiation.
Other rare (21q) is not related to maternal age
Clinical presentation of of Down Syndrome?
Appearance: Growth failure, small, square head w/ flat facial profile and depressed nasal bridge. EYES epicanthal folds, and upward slant. EARS: small stubby malformed. MOUTH: open w/ protruding tongue. HEART: Congenital heart disease. INTESTINAL malformations. BONES: acute lymphoblastic leukemia
MENTAL health and emotional problems
mild –moderate intellectual disabilities. Delayed development of language and speech, poor attention and impulse control
Hearing loss/impairment
Congenital heart disease
Delayed development of language and speech, poor attention and impulse control
What are the screening tests for DS?
Blood test to measure maternal serum levels of various markers.
Ultrasonography to measure fetal nuchal transparency.
Collect genetic material via percutaneous umbilical sampling
Incidence in relation to maternal age?
25yrs- 1 in 1250
35yrs- 1 in 400
45yrs- 1 in 100
What is nondisjunction?
The failure of homologous chromosomes or sister chromatids to separate properly during cell division
Tx?
Treat complications and MNFTS
How many people
- 1 in 800 births, most common chr disorder
Connection to another disease
Alzheimers
