Doubt cast over predictive genetic tests for heart disease

A study published in the Journal of the American Medical Association has cast doubt over the accuracy of predictive genetic tests for acute coronary syndromes (ACS). A team lead by Dr Thomas Morgan, formally of the Yale University School of Medicine, New Haven, Connecticut, studied DNA samples from over 800 ACS patients and 650 unaffected individuals. The findings revealed no significant link between the occurrence of ACS and 84 gene variants previously reported in smaller studies, with only one being nominally significant.

Only 41 of 84 of the supposed risk variants were even slightly more frequent in the patients than in the healthy controls At least seven of the variants are already use in commercial tests to predict the risk of ACS, available to doctors but not to patients directly, with others being used in the clinical trials stage.

'Our findings come at a critical juncture in complex disease genetics. Some cardiovascular gene variants included in our study can already be ordered clinically, for indications that explicitly include possible ACS risk', said Dr Morgan. He continued: 'Our findings suggest that such clinical genetic testing is premature and underscore the importance of robust replication studies of reported associations prior to their application to clinical care'.

Dr Morgan's study is, however, the first case of evidence against the gene variants. Robert Zee, a geneticist at Harvard Medical School and who worked on the gene variants tested in the study, said that 'one needs to interpret all of these genetic findings - including this particular paper - with caution. We still cannot yet claim that none of these would be a suitable risk factor'. Identifying the genetic contribution to complex conditions such as heart disease presents a major challenge to researchers, since many genes and other factors are thought to be involved.