An abnormal gene carried by 1 in 9 blacks confers a 24-fold increase in sudden infant death syndrome in infants who receive a copy from each parent

Thomas H. Maugh II:

Blacks have a higher incidence of SIDS than other ethnic groups, and the mutant gene, which also causes an increased risk of heart arrhythmias in adults, may play a role in that risk, according to the report in the Journal of Clinical Investigation.

Significantly, the effects of the gene can be mitigated in adults with drugs, and it may be possible to block its effects in at-risk children, the researchers said.

The mutant gene alone does not cause SIDS, said Dr. Steven Goldstein of the University of Chicago, who led the study.

"Our findings suggest that it renders infants vulnerable to environmental challenges, such as a long pause in respiration, that are tolerated by children without the mutation," he said.

The gene, called SCN5A, is not the first to be associated with SIDS, but it is the first to be linked to a specific ethnic group and it seems to produce a greater increase in risk than previously discovered mutations.

Still, it appears to account for only about 5 percent of SIDS deaths in blacks.

"Anything we can find that brings us closer to understanding the deaths is a big deal," said Dr. Dorothy Kelly of the Littleton Regional Hospital in Littleton, N.H., president-elect of the American Association of SIDS Prevention Physicians.

"We've been looking for 30 years and even a little nubbin of help is important."

SIDS is the most common cause of death in infants between 1 month and 1 year, striking about 2,500 children in the United States each year. It typically strikes without warning while the child is sleeping, hence its common name, "crib death."

The prevalence has been halved in recent years by campaigns encouraging parents to put infants to sleep on their backs, but there are clearly other risk factors.

Genetics is one of those factors. Blacks are three times as likely as whites to die from SIDS and six times as likely as Latinos and Asians.

Common Gene Variant Linked to African American SIDS

A genetic clue to high SIDS rate in black infants

Gene Variant Raises SIDS Risk for Black American Infants