Angiotensin converting enzyme insertion/deletion polymorphisms in vasovagal syncope.

UNLABELLED: Recent studies suggest vasovagal syncope (VVS) has a significant heritable component (crude estimate sibling relative risk (lambda(s)): 1080) indicating that at least some forms of VVS may have a genetic cause. Here we present the first study examining a potential genetic abnormality in VVS.

METHODS

DNA was collected from consecutive patients attending our unit with head up tilt confirmed VVS (n=165). One hundred and fourteen affected and unaffected first-degree relatives of those with a definitive diagnosis of VVS and positive family history also provided DNA.

RESULTS

DNA from 165 VVS index cases was genotyped for the ACE insertion/deletion polymorphism. Mean+/-SD age of cases was 56+/-19 years (103 (62%) females). There was no significant difference in distribution of ACE insertion or deletion gene frequencies in cases compared with a large (>6000 subjects) national control population. No preferential transmission of alleles in families was identified using tests of association (P=0.1789)

CONCLUSION

We have shown using both a case control and a small family based association study that polymorphisms of ACE alone are not associated with increased risk of VVS. Further studies are planned to clarify the genotype/phenotype relationship in VVS and examine other candidate genes.