WIKIMEDIA, EKEM, MIKAEL HAGGSTROMA team of researchers from Israel and the U.S. has developed the first lines of human, haploid embryonic stems cells, according to a study published yesterday (March 17) in Nature. The cells offer a new tool for efficient genetic screening and drug tests, as well as a potential means to produce eggs and sperm for infertile couples.

“In diploid cells, mutating just one copy of a gene usually does not produce a biological effect because there is always a second copy that serves [as] a ‘backup,’” study coauthor Ido Sagi of Hebrew University told STAT News. “Learning about the genetic basis of how drugs work in treating certain diseases requires a haploid genome with only one copy of each gene—where every mutation would have an effect that we will be able to learn something from.”

In mammals, gametes (eggs and sperm) are normally the...