Factor VII Padua defect: the heterozygote population.

14 heterozygote patients, belonging to three families with factor VII Padua defect were investigated. All patients were asymptomatic but presented a mild prolongation of prothrombin time. Factor VII activity varied between 45 and 61% of normal and no overlap was found with the homozygous or the normal populations. On the contrary, factor VII cross-reacting material was normal. A good negative correlation was found between factor VII level and prothrombin times. All patients came from the same valley of northeastern Italy. This valley, the Piave river valley, is not far from the valley where the factor X Friuli defect was found. The significance of this peculiar geographical distribution of the two abnormalities is unknown.