ABCB1 and Other metabolic disease: Earlier studies have shown that the frequency of specific genetic variations in the ABCB1 gene varies between races.5 Ethnic differences are seen in the occurrence of metabolic diseases.37 Interestingly, a meta-analysis of BMI and different ethnic groups found small but significant differences in the use of BMI to predict total body fat when comparing ethnic groups with a prediction model made from Caucasian data.