Question

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

Answer 1

Answer: (B)

Turner's syndrome is due to monosomy $(2n - 1)$. It occurs by the union of an allosome free egg $(22 + 0)$ and a normal $X$ sperm or a normal egg and an allosperm free sperm $(22 + 0)$.
Turners' syndrome (most common type of female genetic disease) having $XO$ genotype is caused by the absence of $X$ chromosomes in female. These are sterile females with poorly developed ovaries, small uterus and underdeveloped breasts. They have webbed neck and broad chest. The individual has $2n = 45$ chromosomes $(44 + XO)$ instead of $46$.