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Which one of the following conditions in humans is correctly matched with its chromosomal abnormality/linkage?

Correct answer: C. Klinefelter's syndrome ­: 44 autosomes + XXY

  • A. Erythroblastosis foetalis :­ X-­linked
  • B. Down's syndrome ­: 44 autosomes + XO
  • C. Klinefelter's syndrome ­: 44 autosomes + XXY
  • D. Colour blindness ­: Y-­linked

Explanation

Klinefelter's syndrome is a genetic disorder in which there are three sex chromosomes, XXY, rather than the normal XX or XY. The number of autosomes are normal i.e., 44. Affected individuals are apparently male but are tall and thin, with small testes, failure of normal sperm production (azoospermia), enlargement of the breasts (gynecomastia), and absence of facial and body hairs.

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About Inheritance

Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.

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