<prompt> Young male presents with delayed puberty with decreased FSH, LH, and testosterone. Which of the following is NOT possible?Kallmann syndromeKlinefelters syndromeConstitutional delayDAX-1 gene mutation  <response>: Ans. is b, i.e Klinefelters syndromeRef: Leon Speroff 7thed, p404-407 Decrease in serum follicle-stimulating hormone FSH, luteinizing hormone LH, and testosterone indicates that this is a case of hypogonadotropic hypogonadism. Hypogonadism resulting from hypothalamic or pituitary defects is called as hypogonadotropic hypogonadism or central hypogonadism. Examples of hypothalamic defects include Kallmann syndrome. Examples of pituitary defects include hypopituitarism. DAX-1 dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1 is a nuclear receptor protein. Mutations in this gene result in both X-linked congenital adrenal hypoplasia and hypogonadotropic hypogonadism. Hypogonadism which results from defects of the gonads is called as primary hypogonadismhypergonadotropic hypogonadism. Examples include Klinefelter syndrome, mumps, varicocele, etc.In Klinefelters Testosterone is decreased, which results in increase in LH and FSH. 