Human Sperm Genome Sequencing May Help Infertile Men
Researchers have mapped the entire genome of the human sperm, according to a new study, published in the journal Cell. The project marks the first time a human sex cell has been sequenced entirely, and researchers said the findings will help shed new light on the vast amounts of variation the occurs within men.
"We learned some really interesting details about how the body mixes together the genomes from parents to create new genomes for their potential children," Steven Quake, study author and , professor of bioengineering and applied physics at Stanford University, told Fox News. "That's why every sperm cell has a different genome. Your body mixes to create unique genomes so your offspring have different genetic diversity."
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Researchers analyzed over 100 sperm from 40 healthy men and compared the sequences with the man's whole-genome sequence, which allowed them to figure out where recombination, the breaking apart and rejoining of chromosomes during reproduction, takes place.
Cells typically carry two copies of each of our 23 chromosomes. Recombination occurs during cell reproduction and ensures that when a sperm fertilizes an egg, the embryo has a full set of DNA. However, when chromosomes align during recombination, some parts are randomly swapped out -- a process known as "genetic mixing." This allows for vast amounts of genetic variation among children.
Each sperm underwent approximately 23 recombination events. However, the degree of genetic recombination varied greatly between each individual sperm. Genetic mutations also play a role in creating diversity among the men's children.
"[Before this study], we have no way to catalogue the mutations and the recombination events of an individual," Barry Behr, study coauthor and professor of obstetrics and gynecology at Stanford, told Fox News. "Once we get our understanding of these, we can map them and see how they change as a man ages. We could map these in healthy versus unhealthy people. We could map these in fertile and infertile people, and really get a better understanding as to what the fundamental makeup of a good sperm versus a bad sperm is."
Behr said the findings will also help researchers better understand what makes some men infertile.
"I would put money on the fact that we or others will be able to demonstrate using our approaches that infertile men have higher mutation rates or have different types of mutation rates than those men who have normal fertility rates," Behr said. "That in and of itself will be a huge contribution to understanding fertility, but specifically male fertility, which is really a decade or two behind studying female fertility."
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