All are true regarding Klinefelter's syndrome except:
Ans: B (Webbing of neck) Ref: Robbins Pathologic Basis of Disease, 8th edition.Explanation:Webbing of neck is characteristically seen in Turner's syndromeKlinefelter SyndromeMale hypogonadism that occurs when there are two or more X chromosomes and one or more Y chromosomes.MC genetic disease involving the sex chromosomesMost common cause of hypogonadism in the male.Incidence 1 in 660 live male birthsIt can rarely he diagnosed before puberty because the testicular abnormality develop late.Distinctive body habitus -Increase in length between the soles and the pubic bone ->> elongated bodyEunuchoid body habitusLong legsSmall atrophic testesSmall penisLack of secondary male characteristics as deep voice, beard & pubic hair.GynecomastiaThere is increased incidence ofType 2 diabetesThe metabolic syndromeMitral valve prolapse in 50%.Autoimmune diseases (SLE)Breast cancer (20 times more common than in normal males)Extragonadal germ cell tumors||Plasma gonadotropin concentrations (FSH) & || testosterone levelsT Plasma estradiol levels (Unknown mechanism)The ratio of estrogens and testosterone determines the degree of feminization in individual cases.Reduced spermatogenesis and male infertilityTesticular tubules are totally atrophied and replaced by pink, hyaline, collagenous ghosts.Sometimes, apparently normal tubules are interspersed with atrophic tubules.In some patients all tuhules are primitive and appear embryonic, consisting of cords of cells that never developed a lumen or progressed to mature spermatogenesis.Leydig cells appear prominent, as a result of the atrophy and crowding of tubules and elevation of gonadotropin concentrations.The classic pattern of Klinefelter syndrome is associated with a 47, XXY karyotype (90% of cases).This complement of chromosomes results from nondisjunction during the meiotic divisions in one of the parents.15%' of patients w ith Klinefelter syndrome have been found to have a variety of mosaic patterns, most of them being 46, XY/47, XX\r (Other patterns are 47, XXY/48, XXXY )Turner SyndromeTurner syndrome results from complete or partial monosomy of the X chromosome and is characterized primarily by hypogonadism in phenotypic femalesIt is the most common sex chromosome abnormality in females.Three types of karyotypic abnormalities are seen in Turner syndrome.Entire X chromosome is absent (57%), resulting in a 45 XO karyotype.Structural abnormalities of the X chromosomes (14%)Mosaics (29%).Examples of karyotypes that mosaic Turner females may have are the following: (1) 45,X/ 46, XX; (2) 45. X/46. XY; (3) 45, X/47, XXX; or (4) 45, X/46. X. i(X)(ql0).The mosaics with a Y chromosome-containing population (e.g., 45. X/46, XY karyotype) may be at risk of developing GonadoblastomaClassical Features of Turners syndromePresent durings infancy with edema of the dorsum of the hand and foot due to lymph stasis. Swelling of the nape of the neck (due markedly distended lymphatic channels leading on to cystic hygroma)Bilateral neck webbingPersistent looseness of skin on the back of the neck.Congenitat heart disease (esp preductal coarctation of the aorta and bicuspid aortic valve)Failure to develop normal secondary sex characteristics.Turner syndrome is the single most important cause of primary amenorrheaApproximately 50% of patients develop autoantibodies to thyroid gland, and can develop hypothyroidism.Glucose intolerance, obesity, and insulin resistance in minority of patients
Small Testes
Webbing of neck
Gynecomastia
Increased FSH levels
Mendelian Disorders: Single-Gene Defects