Q14 - Cytogenetic Analysis of Sex Chromosome Abnormalities
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Q14. Two individuals P (45 chromosomes, 0 Barr bodies, no SRY, rudimentary gonads) and Q (47 chromosomes, 1 Barr body, SRY present, small testes with gynecomastia) were analyzed. Which interpretation best explains these findings?
a P: Loss of one X chromosome after fertilization (post-zygotic nondisjunction) -> mosaic; Q: Gain of one Y chromosome -> abnormal testicular development b P: 45,XY complement with SRY mutation -> defective testis differentiation; Q: 47,XYY -> enhanced spermatogenesis c P: Loss of one sex chromosome during gametogenesis -> monosomy with female phenotype due to absence of SRY; Q: Gain of one sex chromosome during gametogenesis -> presence of Y initiates male development but extra X causes partial feminization d P: Duplication of X chromosome -> overexpression; Q: Loss of one X -> male by default
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