DALLAS - August 27, 199 - The discovery by UT Southwestern Medical Center at Dallas researchers that an enzyme deficiency is responsible for some infant deaths attributed to Sudden Infant Death Syndrome (SIDS) could lead to new postnatal testing to identify those at risk.
"Our observations suggest that this deficiency is a severe disorder contributing to early infant death," said Dr. Michael J. Bennett, a professor of pathology and pediatrics at UT Southwestern and director of clinical chemistry at Children's Medical Center of Dallas. "The defect is a deficiency in the SCHAD - short-chain L-3-hydroxyacyl coenzyme A dehydrogenase - enzyme."
The findings were published in the July/August issue of Pediatric and Developmental Pathology.
The deficiency occurs during the breakdown of fatty acids derived from fat stores in the body. The body uses these fats as an energy source when its normal energy supply of glucose, which is converted into glycogen, is used up. In the event of fasting, infants tend to exhaust their limited glycogen supply quickly and begin using the stored fat, Bennett said.
The clinical consequences of SCHAD deficiency -- an inborn error of metabolism -- occur when fatty acids from the stored fats enter the liver and fail to generate energy or to produce ketones. Ketones are a vital energy source for the brain because it cannot use fatty acids, unlike the heart and skeletal muscle, which use fat directly.
"In these infants, fat can get into the liver, but it can't be metabolized and released," Bennett said. "Hence infants' brains starve from the deficit of ketones, and they become comatose."
The researchers examined 150 cases for this study. While only 2 percent were due
to SCHAD deficiency, the researchers hope their findings will prevent at least a
small portion of the unexpected fatalities previously described as SIDS cases by
developing immediate postnatal testing that would identify infants with the
Contact: Jennifer Haigh
UT Southwestern Medical Center