questions 4

Klinefelter Syndrome

Topic updated on 12/08/17 11:13am

Snap Shot
  • A 24-year-old man with infertility is noted to have gynecomastia, atrophic testes, and azoospermia.
  • 47 XXY resulting from nondisjunction or translocation
    • one X chromosome becomes a Barr body
  • Occurs in 1/1000 males
    • 1/100 of those who are mentally retarded
    • common cause of infertility during workup
  • Pathogenesis
    • dysgenesis of seminiferous tubules and loss of Sertoli cells
      • leads to ↓ inhibin and resultant ↑ FSH
      • FSH upregulates aromatase leading to increased conversion of androgens to estrogens 
    • Leydig cell dysfunction
      • leads to ↓ testosterone
      • without negative feedback of testosterone there is an ↑ LH
  • Diagnosis 
    • seldom made before puberty
    • Karyotyping is diagnostic test of choice
  • Physical exam
    • hypogonadism
    • long extremities (eunuchoid body shape)
    • female hair distribution
    • gynecomastia
    • azoospermia
    • testicular atrophy
  • Laboratory
    • labs show elevated
      • aromatase
Prognosis, Prevention, and Complications
  •  Testicular neoplasms
    • ↑ risk for testicular neoplasms


Qbank (4 Questions)

(M1.RP.1) A 25-year-old male visits his physician because of fertility issues with his wife. Physical exam reveals bilateral gynecomastia, elongated limbs, and shrunken testicles. Levels of plasma gonadotropins are elevated. Which of the following is also likely to be increased in this patient: Topic Review Topic

1. Testosterone
2. Inhibin
3. Aromatase
4. Ejaculatory sperm
5. Sertoli cells

(M1.RP.27) A young Caucasian couple in their late twenties present for an infertility evaluation after trying to conceive over 2 years. On physical exam, the female appears healthy and states that she has regular menstrual cycles. The male partner is noted to have long extremities with wide hips, low muscle mass, gynecomastia, sparse facial or chest hair, and small, firm testes. Laboratory tests of the male partner reveal elevated serum LH and FSH and low testosterone levels. If cytogenetic tests were performed, which of the following would be seen in this male? Topic Review Topic

1. Presence of a barr body
2. Absence of a barr body
3. Absence of a second sex chromosome
4. Trisomy of chromosome 13
5. Trisomy of chromosome 18

(M1.RP.73) A 30-year-old man presents for an infertility work-up. He and his wife have been unsuccessfully trying to get pregnant for 12 months. The patient has no known history of medical conditions. Physical exam was notable for features depicted in Figure A. Laboratory testing showed increased levels of FSH and LH.

Which of the following is the most likely explanation for this patient's presentation? Topic Review Topic
FIGURES: A          

1. 47 XYY chromosome disorder
2. 47 XXY chromosome disorder
3. Chloride ion transporter defect
4. Androgen insensitivity
5. Defective migration of GnRH cells

(M1.RP.6005) A 19-year-old male from rural West Virginia presents to his family medicine doctor to discuss why he is having trouble getting his wife pregnant. On exam, he is 6 feet 2 inches with a frail frame and broad hips for a male his size. He is noted to have mild gynecomastia, no facial hair, and small, underdeveloped testes. He claims that although he has a lower libido than most of his friends, he does have unprotected sex with his wife. His past medical history is notable for developmental delay and difficulties in school. What is the most likely chromosomal abnormality in this patient? Topic Review Topic

1. Trisomy 13
2. Trisomy 21
3. 47: XYY
4. 47: XXY
5. 45: XO


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