Question

A disease caused by an autosomal primary non-disjunction is :

• A. Down's Syndrome
• B. Klinefelter's Syndrome
• C. Turner's Syndrome
• D. Sickle cell anemia

Answer 1

The correct option is A Down's Syndrome

Down's Syndrome is a genetic disorder caused due to the presence of an additional copy of chromosome 21 (trisomy of 21) as result of an autosomal primary non disjunction which is the failure of homologous chromosomes or sister chromatids to separate properly during cell division in autosomal (not sex) chromosomes.

Klinefelter's Syndrome (XXY) and Turner's Syndrome (XO) are caused by non-disjunction of sex chromosomes while sickle cell anemia is caused due to mutation in the genetic code (causing a shift from glutamine to valine).