Unexpected source of genetic diversity found in human sperm
Scientists have identified an unexpected source of genetic variation in human sperm that occurs earlier in sperm development than previously thought. Published in Nature, researchers at the Wellcome Sanger Institute, the University of Cambridge and their collaborators found that one type of genetic recombination involving chromosomes, called non-crossover gene conversion, happens before the cell…
Scientists have discovered that a significant amount of genetic variation in human sperm originates from a previously unrecognized source – DNA copying events that occur during normal cell divisions before meiosis begins. Published in Nature, researchers from the Wellcome Sanger Institute and the University of Cambridge analyzed 15 sperm samples from 13 donors aged 24 to 74 using advanced long-read sequencing technology.
This revealed that 2,382 non-crossover gene conversion events, a type of genetic recombination, took place in the premeiotic cell divisions that maintain sperm-producing cells throughout a person's life. These events, which carry molecular signatures similar to DNA repair mechanisms found in normal body tissues, varied between individuals, including identical twins.
The findings challenge the conventional view that most genetic recombination occurs during the specialized meiosis cell division. The researchers discovered that this premeiotic DNA copying contributes more to genome diversity in sperm than previously thought, opening new avenues for studying fertility, genomic evolution, and inherited diseases.
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