Question

In humans, Philadelphia chromosome results from the reciprocal translocation between chromosome number

• A. 20 and 9
• B. 9 and 21
• C. 3 and 11
• D. 9 and 22

Answer 1

The correct option is D 9 and 22

Translocation between chromosome numbers 9 and 22 produces "Philadelphia chromosome (Ph chromosome)". The translocation occurs in a single bonemarrow cell which in turn produces many mutant cells through the process of clonal expansion and causes leukemia. Reciprocal translocation between chromosome number 20 and 9 causes male infertility. Since, chromosome 21 is an acrocentric chromosome; reciprocal translocation between chromosome number 21 and 9 is a Robertsonian type and causes abnormal offspring or miscarriage owing to unbalanced gametes. Reciprocal translocation between chromosome number 3 and 11 causes many pregnancy complications.