In the following karyotype, what is the abnormality seen? Shows 2 X-chromosomes and 1 Y-chromosome.
Correct Answer: Gynecomastia with long thin limbs
Description: Klinefelter syndrome Genetic mechanism: Due to nondysjunction of either maternal or paternal X gene during meiosis, the male fetus will inherit one Y chromosome and more than one X chromosome. Remember, the chance of getting an extra X chromosome from the father or the mother is equal. Karyotype: 47XXY (common). Mosaics like 46,XY/47,XXY and 47,XXY/48,XXY are also seenPathogenesis: Except one X chromosome in the fetus all the other X chromosomes bears an active androgen receptor (that is represented shoest CAGrepeats). The shoer the CAG repeats, moreactive the receptor is. Since the X chromosomes were inactivated, the fetus develop "hypogonadism"Clinical features : (All these presentations are secondary to male hypogonadism)*Long lower limbs*Lower IQ level (But no mental retardation)*Gynecomastia *Atrophied testes, small penis , male infeility*Loss of secondary sexual characteristics like deep voice, beard and male distribution of pubic hair. Other associations :*Type 2 diabetes , metabolic syndrome and mitral valve prolapsedLab findings : *FSH elevated, testosterone reduced and increased estradiol(Ref: Robbins 8/e p165)
Category:
Pathology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now