High factor VIII plasma levels as a risk factor for venous thrombosis: no evidence of inheritance from a family cohort study

We assessed inheritance of high factor VIII:C (FVIII:C greater than or equal to150%) levels in 52 probands carrying factor V Leiden and 176 first-degree relatives. Although age-adjusted FVIII:C levels aggregated within families, relatives of probands with FVIII:C levels greater than or equal to150% and <150% were comparable regarding median FVIII:C levels, cumulative distribution curves, and annual incidence of venous thromboembolism. Aggregation of high FVIII:C levels could not be explained by inheritance and was not predictable from FVIII:C levels in probands