​Pathology - Down Syndrome

​Pathology - Down Syndrome 
95% of cases are caused by trisomy 21 (typically due to meiotic nondisjunction). Trisomy 21 becomes more common as women age, resulting in 1 in 25 infants to moms over 45 having Down syndrome.
Four percent of instances are caused by Robertsonian translocation. Chr 21's long arm is translocated to a different chromosome, typically chromosomes 14 or 22.
Mosaicism, which makes up 1% of cases, is caused by chr 21's nondisjunction during mitosis during embryogenesis.

Features 
Extremely delayed development; atresia of the duodenum and esophagus; palmar crease in one hand only; small hands with simian crease; distinct features of the face: flat face, epicanthal folds, wide-set eyes, and Brushfield spots (white spots around the iris).

Congenital heart problems include AV valve anomalies, VSDs, and ostium primum ASD caused by endocardial cushion deficiencies.
Difficulties 
Middle-aged individuals with Down syndrome are more likely to experience acute leukemias, be more vulnerable to infections, and experience degenerative brain changes that resemble Alzheimer's disease.

 Duodenal atresia and congenital cardiac abnormalities should be treated as needed.
Prognosis: Life expectancy is decreased, yet more than 80% of patients live past the age of thirty.