PubMed · 13874784
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R B BURFORD. 1962. The undescended testis.. https://pubmed.ncbi.nlm.nih.gov/13874784/
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BACKGROUND: A specific haplotype (AGATA) in the estrogen receptor alpha (ER1) gene was recently described as a new risk factor for cryptorchidism in the Japanese population. In this ethnic group, single-nucleotide polymorphism 12 (SNP12) was concluded to be the tag SNP for the AGATA haplotype. MATERIALS AND METHODS: A large group of patients (total number=335) and controls (total number=567) of two Caucasian populations were analysed for the AGATA haplotype and SNP12 to verify whether this genetic variant and its tag SNP were associated with cryptorchidism or with severe spermatogenic failure. RESULTS: We confirm that SNP12 is the tag SNP for the AGATA haplotype also in Caucasians. However, in contrast with the Japanese population we found a protective effect for ESR1 SNP12 on cryptorchidism in the Italian population. No association between SNP12 and severe spermatogenic disturbances was observed. CONCLUSIONS: The observed associations (although with opposite effect) with cryptorchidism encourage future studies on independent cases and controls from different ethnic and geographic origins. On the other hand, in contrast with other ESR1 polymorphisms, SNP12 polymorphism is not associated with severe male factor infertility in two independent European population.
Estrogens are classically known to play a major role in female reproduction but there is now compelling evidence that they may also be involved in the regulation of male reproductive function. In humans, a decrease in sperm count and an increase in the incidences of testicular cancer, cryptorchidism and hypospadia have been observed in many countries over the last 50 years. Male reproductive alterations were also observed in wildlife. Such male reproductive disorders have been attributed to the increase in concentration of xenobiotics, and of xenoestrogens in particular, in the environment and in food. Epidemiological, clinical and experimental studies have suggested that excessive exposure to estrogens during fetal/neonatal life can lead to reproductive disorders in adulthood. Using an in vitro model we showed that estrogens directly affected the development of the fetal testis and we evidenced the existence of periods of sensitivity throughout development. Lastly, we clearly demonstrated that the fetal and neonatal testis is very sensitive to estrogens since the invalidation of estrogen receptor alpha leads to an increase of steroidogenesis and the invalidation of estrogen receptor beta enhances the development of the germ cell lineage in the male.
The latest figures from the Cancer Registry of Norway show that Norway has the highest incidence rate of testicular cancer in the world. They also show that the incidence rate continues to increase, as it has for the last decades in the western world. The reasons for this increase, which might also be true for urogenital abnormalities in men and reduced sperm quality, are uncertain. Data suggest, however, that these anomalies originate in foetal life, and that contributing factors are genetic, pregnancy-related and environmental. The potential importance of environmental factors must be taken seriously, and the authorities must take action to strengthen the research in this area.