Question

Due to non-disjunction of chromosomes during spermatogenesis, sperms carry both sex chromosomes (22A + XY) and some sperms do not carry any sex chromosome (22A + O). If these sperms fertilize normal eggs (22A + X), what types of genetic disorders appear among the offsprings?

• A. Klinefelter's syndrome and Turner's syndrome
• B. Down's syndrome and Klinefelter's syndrome
• C. Down's syndrome and Turner's syndrome
• D. Down's syndrome and Cri-du-chat syndrome

Answer 1

Answer: (A)

Klinefelter's syndrome is due to trisomy of sex (X) chromosomes. It is formed by the union of an abnormal XX egg and normal Y sperm or normal X egg and abnormal XY sperm. The individual has 47 chromosomes (44 + XXY). Such persons are sterile males (called feminized male) with undeveloped testes, mental retardation, female-like sparse body hair, and knock knees, long limbs and with some female characteristics such as feminine pitched voice and enlarged breasts (gynaecomastia).
Turner's syndrome occurs due to monosomy, i.e., (2n - 1). It is formed by the union of an abnormal 0 egg and a normal X sperm or a normal egg and an abnormal 0 sperm. The individual has 2n = 45 chromosomes (44 + X), instead of 46. Such individuals are sterile females who have rudimentary ovaries, undeveloped breasts, small uterus, puffy fingers, short stature (less than 5 feet), webbed neck, abnormal intelligence, cardiovascular abnormalities and hearing impairment.