Eighteen Amish children – who mysteriously died over the course of 15 years – had all inherited a faulty gene from the same ancestor, a new report has found.
Mutation of the RYR2 gene found in the heart muscle caused the organ to suddenly stop in the otherwise healthy boys and girls who were running about or playing when they died.
While it’s only 25 per cent likely a child would inherit the mutation from both parents, the likelihood was vastly increased in these cases of two extended families due to the limited gene pool in Amish communities.
Doctors were initially baffled by the spate of heart failure deaths, which cropped up in multiple states including Pennsylvania, Delaware, Kentucky, and Iowa from 2004.
The first death happened in 2004 in Rochester, Minnesota when a 12-year-old girl dropped dead suddenly while playing. Her younger sister died under similar circumstances months later.
When their autopsies came back negative for any known cause of death, baffled coroners reached out to geneticists.
Even the lab they went to, which specializes in unexplained deaths, could not figure out what had caused their heart failure.
RYR2 is a protein found primarily in heart muscle. The mutation appears to cause the heart to suddenly stop beating when heart rate is elevated.
But the scientists were unable to notice these tiny changes inside the gene because technology was only able to look at one gene at a time.
Another child from the same Amish family in eastern USA died six years later and the following year another sibling died.
Four more similar deaths last year allowed researchers to look again.
Advanced technology meant they could peer inside each gene and look at individual strands of DNA.
‘With more information and more technological advancement in terms of being able to look at genes, we were able to put this puzzle together,’ David Tester, the lead scientist on the case, told CNN.
‘As we started building out the family structure, it became apparent to us that this was most likely a recessive disorder.’
The Wind team, part of the Mayo Clinic, found more than 300,000 segments of the RYR2 gene had become duplicated.
The defect can be passed down only if both birth parents had them.
And the mother and father can both live completely healthy without it having any effect on their health.
Out of 23 people who had inherited the mutated gene, 18 died suddenly.
They were from two extended families, which suggested they had a common ancestor.
Experts say the defect has only occurred in Amish children because of their tight-knit communities and they only intermarry with one another.
‘We finally figured it out that it was an autosomal recessive condition where both bad duplications came from both parents, and those children were unfortunate to get the double dose,’ Michael Ackerman, director of the Windland Smith Rice Sudden Death Genomics Laboratory, part of the Mayo Clinic, told CNN.
The Amish are a group of traditionalist Christian church fellowships known for simple living, plain dress, and reluctance to use modern technology.
Experts were only able to figure out the cause of what’s known as ‘the curse of sudden death’ because of families that allowed them to study the genes.
Ackerman said there is only one known treatment for the defect – an Implantable Cardioverter Defibrillator.
An ICD is a small battery-powered device placed in your chest to monitor heart rhythm and detect irregular heartbeats.
It can deliver electric shocks via one or more wires connected to keep the heart beating when its muscles stop.
The researchers say they are working toward a screening test for couples who don’t want to pass on the genes to their offspring.
The abstract of the study said that given the ‘high rate of consanguinity in Amish families, identification of unaffected heterozygous carriers may provide potentially lifesaving premarital counseling and reproductive planning’.
‘Having this genetic biomarker, we can now very easily test any individual for the presence of the mutation,’ Tester said. ‘Having that ability can potentially save lives.’
Ackerman added: ‘We’re going fast and furious to try to get this figured out for this Amish community. We finally have figured out the curse of sudden death for the Amish community and they now have peace of mind as to the reason.’
Dr Ackerman and his colleagues published their findings in JAMA Cardiology.