Answer and Explanation 17

17.  Choice B is the correct answer.  Turner's Syndrome is characterized by a missing second sex X chromosome.  These patients are always female and are infertile.  They have a short stature and are predisposed to congenital abnormalities.  They have an increased incidence of bicuspid aortic valves and coarctation of the aorta.  Children with Klinefelter's Syndrome have multiple X Chromosomes and one or more Y Chromosomes.  These patients are prepubertal boys and there is infertility from low testosterone and low sperm counts.  Trisomy 21 and Trisomy 18 is an extra chromosome on that particular chromosomal set.