Q.
A person with the sex chromosomes XXY suffers from
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AIPMTAIPMT 1997Principles of Inheritance and Variation
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Solution:
Klinefelter's syndrome is an aneuploid condition with 3 sex chromosomes (trisomy). Klinefelter's syndrome is caused by XXY genotype. This genotype results from the union of a nondisjunct XX egg and a normal Y sperm or normal X egg and abnormal XY sperm. The individual has 47 chromosomes (2n + 1). The person having Klinefelter's syndrome is a sterile male with small testes, unusually long legs, obesity, and sparse body hair, and with many female characteristics such as breasts. The victim usually has normal intelligence. The more the X chromosomes, the greater is the mental defect. Klinefelter's syndrome occurs about once in 2000 live births. Turner's syndrome is formed by the union of an abnormal O egg and a normal X sperm or a normal egg and an abnormal O sperm. The individual has 45 chromosomes (44 + X). Down's syndrome is caused by the presence of an extra chromosome number 21. Gynandromorphism is a phenomomenon by which one part of the body of an animal is male and the other part is female.