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Klinefelter syndrome {47 XXY}

Most Common sex aneupluidy in males.


Due to meiotic non- disjunction of an X chromosome during gametogenesis. Q


The extra X chromosome is maternal in origin in 54% and paternal origin in 46% of patients. Q


Clinical manifestations

  1. The diagnosis is rarely made before puberty because of the paucity or subtleness of clinical manifestations.
  2. Behavioral or psychiatric disorder often be apparent long before defects in sexual development. Q
  3. Diagnosis should be considered in all boys with mental retardation, language difficulties. Attention deficit, school adjustment problems.
  4. Affected children may he anxious, excessively shy or aggressive and they may engage in antisocial acts.
  5. The patients tend to be tall, slim and under weight and having long legs.
  6. Testis tend to small for age, phallus tends to be smaller than average and cryptorchidism or hypospadias may occur in few patient.
  7. About 80% of adults have gynaecomastia Q, they have sparser facial hair. There is an increased incidence of pulmonary disease, varicose vein and cancer of the breast. Q 

Lab findings


The chromosomes should be examined in all patient suspected to have klinefelter syndrome

  1. By mid puberty testicular growth stops, gonadotrophins become elevated and testosterone levels are slightly low.
  2. Inhibin levels are low in men.
  3. Elevated levels of estradiol resulting in a high estradiol: testostorone ratio account for the development of gynecomostia.
  4. After puberty the testicular biopsy shows seminiferous tubular membrane are hyalinized and there is adenomatous clumping of leydig cells, Sertoli cells predominate. Q
  5. Azoospermia is characteristic and infertility is the rule. Q

Treatment Replacement therapy with a long acting testosterone preparation beginning at 11-12 year of age.

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