Fertility treatment may cause molecular changes

An increasingly popular fertility treatment used in cases of male infertility could lead to a slight increase in genetic abnormalities in resulting offspring. It may also affect the cellular machinery inside sperm cells during fertilisation, according to a study of the technique in animals. However, experts say the results are unclear as the study carried out by the Oregon Regional Primate Research Laboratory in Beaverton does not explain whether the treatment causes new genetic problems or merely allows parents with slight gene defects to have similarly affected children who otherwise would not have been born.

Available since 1992, intracytoplasmic sperm injection, or ICSI, involves the direct injection of a single sperm cell into a woman's egg during a normal ICSI procedure. About 20,000 babies have been born world-wide as a result, but the procedure was not tested on animals before it became widely available in fertility clinics.

However, Gerald Schatten, who oversaw the Oregon research, firmly stated that the study does not prove that ICSI causes genetic defects in children. Instead, it shows that the molecular sequence of events that occur at fertilisation changes when a sperm is directly injected into an egg. The Oregon study appears in the April issue of the journal Nature Medicine.