A remarkable study of Sudden Infant Death Syndrome among Amish families has found a gene that may help find a cure, writes Dick Ahlstrom from Pennsylvania
An array of quaint farms dot the low rolling hills of southeastern Pennsylvania, each neat as a pin and complete with house, barn and grain silo. Only on closer inspection do you notice that none of the farms have tractors, cars or electricity connections, inventions that are rejected by the Amish who live in these parts around Lancaster County.
These same folk, who stick to old ways that date back 200 years, have also become a focus for advanced research however, with the possibility that they might be able to help find medical answers for Sudden Infant Death Syndrome (SIDS).
A study of high SIDS rates among Amish families, including 21 deaths in only nine family groups, has identified a gene linked to this tragic disorder. Researchers now hope that this new information may help to identify infants at risk of SIDS and alert parents to the possibility that they might pass on the recessive gene that causes at least one form of the disease.
Details of this important new finding were published in a recent edition of the US Proceedings of the National Academy of Sciences. The research was based on a detailed genetic analysis of blood samples collected from Amish infants and their families.
Samples were collected at the Clinic for Special Children in Strasburg, Lancaster County, which treats Amish and Mennonites with unusual disorders. The genetic analysis was conducted mainly at the Translational Genomics Research Institute, Phoenix Arizona. The researchers, led by Dr Erik Puffenberger at the Clinic, identified a recessive gene which when not working correctly was linked to SIDS. The normal gene is involved in the maintenance of normal breathing and heart rate and also in the development before birth of the testes.
"Clearly this gene, when faulty, causes sudden infant death in the Amish," Dr Puffenberger said. "The question is what impact does this gene have for kids in the general population with SIDS. This opens up a new avenue for SIDS research."
SIDS describes the sudden unexplained death of an infant under one year. The incidence has dropped steeply due to public health campaigns encouraging parents to put babies to sleep on their backs.
The Amish are a valuable group for the study of genetic disorders. Most are descended from a small number of German emigrants. They also tend to marry within their own community, increasing the risk of inherited diseases. They are often referred to as the "Pennsylvania Dutch", despite the fact their background is German and their religious services are in the German language.
The researchers discovered what they described as a "lethal" form of the gene that caused both SIDS but also underdevelopment of the newborn's testes. "Twenty-one affected individuals with this autosomal recessive syndrome were ascertained in nine separate sibships among the Old Order Amish," the authors write in their research report.
Improved skills at pinpointing specific pieces of DNA in the human genome meant that it took less than two months for the Phoenix team to narrow the search for the aberrant gene down to Chromosome 6 and then identify it. It is recessive and requires two faulty copies inherited from its parents for a baby to be affected.
While the faulty gene was not to blame for all SIDS cases it opened up the possibility of a screening test to help identify babies at risk, stated Dr Dietrich Stephan of the Arizona research group. The researchers also want to test for the gene in non-Amish babies to see how commonplace the disorder is in the general population.
The results "shed light" on both SIDS and a disorder of sexual development but also give insights into the regulation of genes, the authors conclude. It is also ironic that a community that clings to old ways and eschews modern conveniences including electricity could find themselves central to an advanced research project that may help to reduce the death and suffering caused by SIDS.