Heritability of albumin excretion rate in families of patients with Type II diabetes

Aims/hypothesis. To study whether albumin excretion rate is an inherited trait in families of patients with Type II (non-insulin-dependent) diabetes mellitus. Methods. We used three different approaches. Heritability of albumin excretion rate was studied in 267 nuclear families from the Botnia Study in Western Finland using parent-offspring regression. Albumin excretion rate was also measured in 206 non-diabetic offspring of 119 Type II diabetic parents with or without albuminuria (albumin excretion rate > 20 mu g/min). Finally, albumin excretion rate was measured in altogether 652 siblings of 74 microalbuminuric and 320 normoalbuminuric probands. To study the potential confounding effect of blood pressure, the heritability of blood pressure was estimated in 718 nuclear families. Results. Using parent-offspring regression, the heritability of albumin excretion rate was about 30%, being the strongest from mothers to sons (35-39% resemblance). The heritability for systolic blood pressure ranged from 10 to 20% and for diastolic blood pressure from 10 to 27%. Offspring of albuminuric Type II diabetic parents had higher albumin excretion rates (median 5.4 [range 1.0-195] vs 4.0 [1.0-23] mu g/min, p = 0.0001) and a higher frequency of microalbuminuria (11 vs 2%, p = 0.012) than offspring of normoalbuminuric parents. Further, siblings of microalbuminuric probands had higher albumin excretion rates than siblings of normoalbuminuric probands (4.1 [0.6-14.5] vs 3.6 [0.2-14.4] mu g/min, p < 0.01). Conclusion/interpretation. The data suggest that albumin excretion rate is an inherited trait in families of patients with Type II diabetes.