#june2020amc1
A 16-year-old boy presents with bilateral diffuse gynaecomastia. He has small testicles and delayed appearance of his secondary sexual characteristics. Chromosomal analysis is requested. Which one of the following chromosomal abnormalities is most likely to be present?
A. Trisomy 21
B. XO
C. XXY
D. XXYY
E. XYY
Explanatory Notes:
47 XXY is the abnormality in Klinefelter's syndrome with an incidence of 1 in 500-1000 male births. It is commonly associated with gynaecomastia.
Trisomy 21 is the cause of Down's syndrome. XO is the abnormality in Turner's syndrome and occurs only in females. 48 XXYY occurs in only 1 in 20,000 male births whilst 47 XYY has an incidence of about 1 in 1000 with often few or no features present.
A 16-year-old boy presents with bilateral diffuse gynaecomastia. He has small testicles and delayed appearance of his secondary sexual characteristics. Chromosomal analysis is requested. Which one of the following chromosomal abnormalities is most likely to be present?
A. Trisomy 21
B. XO
C. XXY
D. XXYY
E. XYY
Explanatory Notes:
47 XXY is the abnormality in Klinefelter's syndrome with an incidence of 1 in 500-1000 male births. It is commonly associated with gynaecomastia.
Trisomy 21 is the cause of Down's syndrome. XO is the abnormality in Turner's syndrome and occurs only in females. 48 XXYY occurs in only 1 in 20,000 male births whilst 47 XYY has an incidence of about 1 in 1000 with often few or no features present.
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