Should test results be interpreted differently for different ethnic groups?
Only the TCF7L2 associated risks have been validated in multiple races and show similar effect in whites, Africans, Hispanics, and Asian populations. CDKAL1 and CDKN2 seem to have equivalent effects in whites (European descent) and Asians. PPARG has so far only been validated in whites. Both deCODE’s studies and many studies of independent research groups have shown that the association of the TCF7L2 gene variant and the likelihood of developing diabetes is quite similar across a wide variety of ethnic groups. However, the average frequency of carrying two copies, a positive result for the test, appears to vary according to ethnicity. For instance, approximately 8-9% of general populations of European or African ancestry studied carry two copies, (Helgason et al, Nat Genet 2007; 39:218-225), compared to only 1% of Japanese studied (Horikoshi et al, Diabetologia 2007; 50:747-751). As a consequence ethnicity has an effect on the likelihood of testing positive for carrying two copies of t
