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The Y chromosome region essential for spermatogenesis
Y Nakahori1, Y Kuroki, R Komaki
1Department of Human Genetics, School of International Health, University of Tokyo, Japan.
Hormone Research
|January 1, 1996
Summary
Y chromosome microdeletions are linked to male infertility in Japanese men. Specific gene deletions, particularly in interval 6, contribute to azoospermia (no sperm) and severe oligozoospermia (low sperm count).
Area of Science:
- Genetics
- Reproductive Biology
- Human Molecular Genetics
Background:
- Male infertility, including azoospermia and severe oligozoospermia, affects a significant portion of the population.
- The Y chromosome plays a crucial role in male fertility, and its structural abnormalities can lead to infertility.
- Previous studies have identified Y chromosome microdeletions as a cause of male infertility, but specific genetic loci involved require further investigation.
Purpose of the Study:
- To investigate the frequency and spectrum of Y chromosome microdeletions in Japanese men diagnosed with azoospermia or severe oligozoospermia.
- To identify specific Y chromosome loci and genes associated with these infertility conditions.
- To explore the relationship between the type of Y chromosome deletion and the resulting phenotype (azoospermia vs. severe oligozoospermia).
Main Methods:
- DNA analysis was performed on 153 Japanese men with cytogenetically normal Y chromosomes presenting with azoospermia or severe oligozoospermia.
- A total of 23 loci on the Y chromosome were examined, including 15 loci within interval 6 (e.g., YRRM1, DAZ) and 8 loci outside this region.
- Microdeletions were detected through genetic analysis of these specific loci.
Main Results:
- Microdeletions were identified in 20 out of 153 individuals (13.1%).
- All observed deletions involved at least one locus within Y chromosome interval 6.
- A common deletion encompassing 10 loci between DYS7C and DYS239, including the DAZ gene, was found in 16 individuals, leading to phenotypic diversity (13 azoospermic, 3 with low sperm production).
Conclusions:
- Y chromosome microdeletions, particularly within interval 6, are a significant genetic cause of azoospermia and severe oligozoospermia in Japanese men.
- The specific deletion pattern, including the presence or absence of genes like DAZ and YRRM1, influences the severity of male infertility.
- The genetic heterogeneity observed suggests that azoospermia caused by Y chromosome long arm deletions may involve multiple genetic factors.