Which of the following syndrome is an example of disorders of sex chromosomes?
The classic form of Klinefelter's syndrome occur due to meiotic non disjunction of sex chromosome during gametogenesis. Klinefelter's syndrome is characterized by small testes, infeility, gynecomastia, eunuchoid propoions, and incomplete virilization in phenotypic males. Biopsies done shows seminiferous tubule hyalinization and azoospermia. They are at increased risk of breast tumors, thromboembolic disease, learning difficulties, obesity, diabetes mellitus, varicose veins. Laboratory investigations shows elevated levels of FSH and LH and low levels of testosterone reflecting primary gonadal failure. Levels of estradiol is increased due to chronic Leydig cell stimulation by LH and because of aromatization of androstenedione by adipose tissue. The increased estradiol/testosterone ratio results in gynecomastia. Ref: Harrison's Principles of Internal Medicine, 18e chapter 349, By John C. Achermann; J. Larry Jameson.
Marfan's syndrome
Testicular feminization syndrome
Klinefelter's syndrome
Down's syndrome