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Arrhythmia gene variants linked to Sudden Infant Death Syndrome
17 January 2007
Latest research indicates that long-QT syndrome (LQTS) gene variants contribute to sudden infant death syndrome (SIDS).
The study revealed that nearly 10% of SIDS victims have mutations or variations in these arrhythmia-susceptibility genes.
SIDS is the third-leading cause of death in the United States, and the leading cause among infants aged 1 month to 1 year, despite campaigns to reduce certain behavioral and environmental risks for the syndrome.
It is thought that a combination of risks, including genetic factors, is involved.
"SIDS is not one disease," explained lead author of the study Alfred George (Vanderbilt University, Nashville, Tennessee, USA). "Multiple conditions can increase the risk of sudden death in an infant. Some have been identified, some have not."
George and team screened for seven genes associated with LQTS in 201 SIDS cases from Norway.
The results showed that 9.5% of SIDS victims harbored mutations and variants that are likely contributors to SIDS.
These included mutations in the sodium channel gene SCN5A, previously associated with LQTS and other unstable heart rhythm conditions and sudden death. The team went on to look at the physiological consequences of these mutations.
"We observed a pattern of SCN5A dysfunction that is reminiscent of what's been observed in LQTS," George explained. "That gives us confidence that the mutations observed in SIDS victims are not benign genetic variants – but rather could increase the risk of potentially lethal arrhythmias."
The findings suggest that there may be strategies to identify whether infants are a carrier of one of these mutations.
Ruling out a population-wide screening program, George said that there may be simpler, cost-effective measures that could be investigated further.
He and colleagues are continuing to analyze other arrhythmia-linked genes identified in the Norwegian-SIDS cohort, and planning studied to determine whether parents of SIDS victims carry the same mutations.
George emphasized: "This is critical because knowing how often mutations are transmitted from parents rather than occur spontaneously will help establish the risk to siblings of SIDS victims."
