Scientists from American Academy of Neurology found that fainting could be a familial trait and can be inherited. But they point out that it is not brought about by a single gene inheritance.
Fainting, occurs when the body reacts to external triggers, such as the sight of blood or any other emotional stress, causing brief loss of consciousness. This condition is also called ‘vasovagal syncope’.
There has been an ongoing debate on the factors that cause fainting – some believe it is caused by genetic factors, others believe it is environmental, while yet others believe that it’s a mixture of both the factors.
Study author Samuel F Berkovic of the University of Melbourne, who is also a member of the American Academy of Neurology says that fainting has a strong genetic component and that there are multiple genes and multiple environmental factors that influence the condition.
51 sets of twins aged 9-69, who belonged to the same gender and who formed the subjects of the study, were handed over a telephone questionnaire. At least one of each twin studied harbored a history of fainting. Family history was also taken into account. 57% of the 51 sets of twins had the typical triggers.
The research found that in the case of maternal twins, if one fainted chances are that the other fainted too. However, in fraternal twins that was not the case, especially when fainting was not associated with external factors such as dehydration.
The study concludes that identical twins have greater chances of experiencing fainting triggered by typical factors compared to fraternal twins. In non-twin relatives the frequency of fainting was usually low suggesting that fainting is not a single gene trait.
The current study has been published in the journal Neurology.
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