[Genetics in neurocardiogenic syncope]

Syncope is a symptom, defined as a transient, self-limited loss of consciousness, usually leading to falling. Syncope is a common clinical problem accounting for 5% of hospital admissions and up to 3-5% of emergency department visits. Neurocardiogenic syncope is the most frequent. Vasovagal syncope, carotid sinus syndrome and glossopharyngeal and trigeminal neuralgia are numbered. Clinical descriptions of familial vasovagal syncope are scarce. Studies indicate a strong heritable component to the etiology of vasovagal syncope in over 20% of cases. There are no published molecular genetic studies in vasovagal syncope. There are several studies evaluating gene polymorphism in orthostatic hypotension and intolerance: the endothelin-1 gene (insertion variant in the 5'UTR), B1-adrenergic receptor gene (polymorphism beta1Gly49), the human norepinephrine transporter gene (polymorphism Ala457Pro), Gs protein alpha-subunit (polymorphism T131C) and G-protein beta 3 subunit (polymorphism C825T), and SCNN1G gene encoding the gamma subunit of the amilorid-sensitive epithelial sodium channel. Moreover there are reported the presence of multiple point mutations in the mitochondrial DNA (mtDNA) in three families with orthostatic hypotension. Molecular genetic studies in vasovagal syncope make possible the further explanation of the pathophysiology and the evaluation of individual prognosis and optimal management.