“Klingon Cloaking Device” May Be Key to Male Infertility

The lack of a protein that normally coats sperm may be the reason why some sperm don’t reach the egg to fertilize it.

This protein acts as a “Klingon cloaking device” to allow sperm to swim through cervical mucus and avoid the immune system on its long journey to the egg, says Gary Cherr, a professor at the UC Davis Bodega Marine Laboratory and Center for Health and Environment.

The protein DEFB126 is generated by a specific gene, and men with two copies of the defective gene do not produce the protein, the researchers reported in a study published online on July 20 in the journal Science Translational Medicine.

Some 70% of men have infertility that can’t be explained based on their sperm count and quality, say the researchers.

This discovery may help explain a significant portion of this infertility.

In tests of men worldwide, they found about half of all men carry 1 defective copy.

One quarter have 2 defective copies and therefore make sperm that are poor at swimming through cervical mucus.

In studying about 500 couples in China who were trying to become pregnant, they found that men with 2 copies of the abnormal gene were 30% less likely to father a child over about a 2-year period.

And it took nearly 2 months longer for the couples to have a baby if the man had 2 copies of the abnormal gene.

The researchers are now looking to develop a test for the mutation.

If a couple found that the man has a double mutation, they could go directly to single-sperm injection with intracytoplasmic sperm injection, or ICSI, to inseminate the woman’s egg.

Choosing a healthy sperm becomes crucial to ICSI success.

In a natural conception, only the fittest and healthiest sperm makes the arduous journey to the egg.

ICSI bypasses this natural selection barrier, so the chances of a genetically abnormal sperm fertilizing an egg are higher.

A new test for sperm DNA damage could help select the best sperm for a single-sperm injection.

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