Sex Chromosome Aneuploidy and Structural Rearrangement

Abstract

Abstract There are four major sex chromosome abnormalities due to complete aneuploidy. Otherwise unassisted, infertility is practically inevitable in XXY Klinefelter syndrome and 45,X Turner syndrome. The other two conditions, XXX and XYY, apparently have little effect on fertility; furthermore, they are not discernibly associated with any increased risk for chromosomally abnormal offspring. This chapter first discusses these classic pure sex chromosomal aneuploidies. Then, deletion/duplication states of the X and Y chromosomes are reviewed, whether large and known since classical cytogenetics, or those only having come to light due to the power of twenty-first century mole..