New research has suggested that many miscarriages, birth defects and neonatal deaths may be caused by a genetic defect. Researchers at the University of Toronto, Canada, have shown that many women may be susceptible to miscarriage or of having children with birth defects if they carry genes for a common enzyme deficiency. It is understood that about 400 million people, roughly seven percent of the world population, have this enzyme deficiency. The incidence is higher in some population groups from Africa, Asia and the Mediterranean.
The research has so far been undertaken on mice producing low levels of the enzyme G6PD (glucose-6-phosphate dehydrogenase). The presence of the G6PD enzyme helps maintain levels of glutathione, a peptide that neutralises free-radicals, reactive chemicals in the body that damage cells. Peter Wells, who led the research team, suspected that the G6PD deficiency 'might pose a particular risk to developing embryos, which lack many of the other enzymes that protect against free-radicals'. Female mice with two defective genes for G6PD had smaller litters than normal when mated with defective males. Three times as many pups died during the period immediately after birth as normal.
Further research showed that it was the genes inherited by the fetus that posed the risk - those able to produce the enzyme were more likely to survive, even in the wombs of G6PD deficient mothers. If studies on humans confirm the link between between the enzyme deficiency and miscarriage, it may then be possible to prevent some miscarriages and birth defects by treating women to reduce the levels of free-radicals in their bodies. Wells believes the results shown in the mice are relevant to human miscarriage and birth defects. Lesley Regan, miscarriage specialist at St Mary's Hospital in London agrees that it is 'a matter of urgency now to take these studies forward in humans'.