SEVERAL men with a serious genetic fault have been able to father normal children thanks to the controversial IVF technique known as ICSI.
Men with Klinefelter鈥檚 syndrome have an extra X chromosome. While many don鈥檛 know about the condition until they discover they鈥檙e infertile, others have symptoms such as mental retardation. Since the men cannot produce viable sperm, for the past few years Zev Rosenwaks鈥檚 team at Cornell University has been retrieving immature sperm directly from their testicles. The best-looking ones are used to fertilise eggs from their partners using ICSI, or intracytoplasmic sperm injection, in which a sperm is injected into the egg.
Rosenwaks told a conference in Montreal last month that 9 of the 15 patients with Klinefelter鈥檚 treated this way have managed to have children. All 14 babies have a normal number of chromosomes, even though some parents refused pre-implantation genetic diagnosis to ensure that this was the case.
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The result is surprising because there鈥檚 concern that ICSI allows genetic abnormalities to be passed on to the next generation. Indeed, at the same meeting David Page from MIT reported the results of treating 26 men who were infertile because of a deletion in their Y chromosome. Of these, 11 were able to have children thanks to ICSI, but all 10 sons inherited their father鈥檚 deletion鈥攚hich probably means they will be infertile when they grow up, Page says.
Recent studies also suggest there is an increased, albeit small, risk of birth defects in children conceived with ICSI (快猫短视频, 16 March, p 17). One of the boys in Page鈥檚 study had a severe congenital heart defect, but it is unclear whether it was related to the defect in his Y chromosome or to the ICSI procedure, he says.
Rosenwaks adds that his team is also using the method of retrieving sperm directly from the testicles to help men unable to father children after chemotherapy. 鈥淭hose were patients who were thought to be sterile,鈥� he says.