Scientists have practically obliterated the ultimate symbol of maleness in DNA, the Y chromosome, and believe they may be able to do away with it completely.

They condensed all the genetic information normally found on a mouse’s Y chromosome to just two genes.

Their study, in the journal Science, showed the male mice could still father babies, albeit needing advanced IVF.

The team in Hawaii argues that the findings could one day help infertile men with a damaged Y chromosome.

DNA is bundled into chromosomes.

In most mammals, including humans, one pair act as the sex chromosomes.

Inherit an X and Y from your parents and you turn out male, get a pair of Xs and the result is female.

Two genes ‘enough’

A human X and Y chromosome

“The Y chromosome is a symbol of maleness,” lead researcher Professor Monika Ward told the BBC.

In mice, the Y chromosome normally contains 14 distinct genes, with some present in up to a hundred copies.

The team at the University of Hawaii showed that genetically modified mice with a Y chromosome consisting of just two genes would develop normally and could even have babies of their own.

Prof Ward commented: “These mice are normally infertile, but we show it is possible to get live offspring when the Y chromosome is limited to just two genes by using assisted reproduction.”

The mice could only produce rudimentary sperm. But they could have offspring with the help of an advanced form of IVF, called round spermatid injection, which involves injecting genetic information from the early sperm into an egg.

The resulting pups were healthy and lived a normal lifespan.

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