Infertile men who go in for intra-cytoplasmic sperm injection (ICSI) techniques to have children may risk having sons with infertility. ICSI involves the injection of a single sperm directly into a mature egg. David Page and his group of the Massachusetts Institute of Technology in Cambridge have discovered that a gene was missing from a Y chromosome of men with very low sperm counts. Page says that deletions in this gene called azoospermia factor could be transmitted by ICSI and "would probably result in infertile sons' ( New Scientist , Vol 151, No 2043).