Question

Which genetic disorders, caused by an extra X chromosome (XXY), is characterized by a lack of testicular development in males, effeminate features, possible mental impairment, and a thin stature? A) Down's syndrome B) Turner syndrome C) sickle cell anemia D) Klinefelter's syndrome

Answer 1

Answer:

D

Explanation:

This is caused mainly by nondisjunction of the sex chromosomes in gametes during meiosis. Therefore a gamete will have both XX chromosomes and fuse with a normal one with Y during fertilization. An XY gamete can also fuse with a normal one with X chromosome. These males with Klinefelter's syndrome produce less than normal levels of testosterone.