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10 - Sex chromosome abnormalities and male infertility: a clinical perspective
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- By Shai Shefi, Department of Urology, University of California San Francisco, San Francisco CA, USA, Paul J. Turek, Department of Urology, University of California San Francisco, San Francisco CA, USA
- Edited by Christopher J. De Jonge, University of Minnesota, Christopher Barratt, University of Birmingham
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- Book:
- The Sperm Cell
- Published online:
- 14 August 2009
- Print publication:
- 06 April 2006, pp 261-278
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- Chapter
- Export citation
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Summary
Introduction
Although abnormalities of the Y chromosome have been associated with male infertility since 1976 (Tiepolo and Zuffardi, 1976), it was only in the last decade that the Y chromosome was shown to have regions and genes that govern spermatogenesis. More recently, it has become clear that the X chromosome may be just as important as the Y chromosome in determining male fertility potential. This chapter will review our current understanding of the genotype–phenotype relationships that underlie abnormalities of both the X and Y chromosomes, and discuss recognized syndromes of the gonosomes that are known to cause male infertility.
Y chromosome
Over the last 10 years, there has been significant progress both in analyzing the molecular structure of the Y chromosome and understanding the relationship of Y chromosome mutations to infertility phenotypes. Before its firm association with male fertility, the Y chromosome was widely considered a genetic black hole, a chromosome that evolved as a broken remnant of the X chromosome. It was clear that the Y harbored the male sex-determining region (testis-determining region or sex-determining region Y (SRY)), but it was also home to gene regions that govern stature, tooth enamel and hairy ears as well as ‘junk’ gene regions. Now that the genome of the human Y is known, we realize that this chromosome is structurally unique as a fertility chromosome.
Azoospermia factor
The postulation that deletions in the long arm of the Y chromosome cause azoospermia was made 30 years ago (Tiepolo and Zuffardi, 1976).