Which of the following is an example of disorders of sex chromosomes?
Ans. is 'c' i.e. Klinefelter's syndrome Sexual differentiation can be divided into three major components * Chromosomal sexThe clinical features of patients with disorders of gonadal and phenotypic sex are divided intoDisorder of Gonadal and phenotypic sexundervirilization of 46 xy malesinappropriate virilization of 46 xx femalesThese disorders comprise a spectrum of phenotype ranging from complete "sex reversal" (e.g. 46 xy phenotypic females or 46 xx males) to "ambiguous genitalia". Example of Phenotypic and Gonadal sex disorderDisorders causing undervirilization in karyotypic malesDisorders causing virilization in karyotypic femalesDisorders of Testis developmentOvarian transdifferentiation* True hermaphroditism* True hermaphroditism* Gonadal dysgenesis* XX male* Absent testis syndromeIncreased androgen synthesisDisorders of Androgen synthesis* 21 hydroxylase deficiency* LH receptor mutations* 11 b hydroxylase deficiency* 17CC-Hydroxylase/17,20 lyase deficiency* 3 b hydroxy steroid dehydrogenase* 5a-reductase 2 deficiency* Aromatase deficiencies* Aromatase over expression* Glucocorticoid receptor mutationDisorder of androgen actionIncreased androgen exposure* Androgen insensitivity syndrome* Maternal virilizing tumours* Androgen receptor cofactor defects* Nonvirilizing tumoursOther disorders of male reproductive tractNonvirilizing disorders of the female reproductive tract* Persistent mullerian dust syndrome* Ovarian dysgenesis* Isolated hypospadias* Mullerian agenesis* Cryptoorchidism* Vaginal agenesisPAEDIATRICS
Marfan's syndrome
Testicular feminization syndrome
Klinefelter's syndome
Down's syndrome
Mendelian Disorders: Single-Gene Defects