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    SIDS: Genetics May Play a Role

    Finding Helps Explain Why More Black Infants Die of SIDS
    WebMD Health News

    Aug. 19, 2004 -- The tragic mystery of sudden infant death syndrome (SIDS) is a bit closer to being solved. New research shows that genetics may play a role.

    In a study appearing this month in Pediatrics Research, researchers identify genetic variations, which change the function of proteins among babies who died of SIDS. More than two-thirds were black, reports researcher Debra E. Weese-Mayer, MD, a pediatrician at Rush Children's Hospital at Rush University Medical Center in Chicago.

    Public health officials have been frustrated about the still-high numbers of SIDS deaths. After the nationwide Back to Sleep campaign -- which educated parents on safe sleeping positions for infants -- the numbers of SIDS deaths did decline. Yet black infants still had the highest death rates compared with white infants, writes Weese-Mayer.

    In fact, infants of all ethnic groups continue to have higher SIDS rates. This was true, even though caregivers had carefully followed all safety practices, she says.

    Other studies have provided "strong evidence" pointing to a gene that controls the hormone serotonin, Weese-Mayer says. Serotonin influences a wide range of functions, such as regulating breathing, blood circulation, heart rate, body temperature, and the sleep-wake cycle. Indeed, SIDS infants have had profuse sweating, high temperature, and irregular heartbeat.

    She and her colleagues examined genetic material from brain tissue from 92 SIDS infants -- both white and black infant girls and boys. They compared the results with genetic material obtained from the blood of 92 white and black infant girls and infant boys.

    They found:

    • 11 rare gene variations in 14 of the SIDS infants -- 15% of SIDS infants
    • One gene variation in two of the non-SIDS infants
    • Of SIDS infants with these rare variations in genes that control serotonin, 71% were black

    Similar analyses of brain DNA has helped clarify the genetic basis for a deadly disorder similar to SIDS -- a breathing disorder called congenital central hypoventilation syndrome (CCHS), she explains. Families with genes for CCHS have more cases of SIDS.

    SOURCE: Weese-Mayer, D. Pediatric Research, August 2004; vol 56.

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