A study published in the journal Neurology shows that, in some families, only one gene may be responsible for fainting, also known as vasovagal syncope.
Fainting by Pietro Longhi, c. 1744
Fainting is a brief loss of consciousness when your body reacts to certain triggers. It affects at least one out of four people. The new study led by Prof Samuel Berkovic of the University of Melbourne reveals fainting may run in families while triggers may not.
Prof Berkovic’s team interviewed 44 families with a history of fainting and reviewed their medical records.
Of those, six families had a large number of affected people, suggesting that a single gene was running through the family.
The first family consisted of 30 affected people over three generations with an average fainting onset of eight to nine years.
The other families were made up of four to 14 affected family members. Affected family members reported typical triggers, such as the sight of blood, injury, medical procedures, prolonged standing, pain and frightening thoughts. However, the triggers varied greatly within the families.
Genotyping of the largest family showed significant links to a specific region on chromosome 15, known as 15q26. Linkage to this region was excluded in two medium-sized families but not in the two smaller families.
“Our study strengthens the evidence that fainting may be commonly genetic,” Prof Berkovic said.
“Our hope is to uncover the mystery of this phenomenon so that we can recognize the risk or reduce the occurrence in people as fainting may be a safety issue.”
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Bibliographic information: Karl Martin Klein et al. 2013. Autosomal dominant vasovagal syncope. Neurology, vol. 80, no. 16, pp. 1485-1493; doi: 10.1212/WNL.0b013e31828cfad0
