How common is bleeding disorder?
A Type 1, which affects 70 per cent of those with von Willebrand disease (VWD), occurs in 1 per cent of the population. Type 2, which affects 20-30 per cent of those with VWD, includes four types of von Willebrand factor (VWF). The protein is present but it does not respond normally. In type 1 the protein is reduced, and in type 3 (one in a million) there is hardly any.
Bleeding post tooth extraction is a common presentation. Men often present with sports injuries, and women may have menorrhagia and post-partum bleeding.
VWD is inherited but skips generations. In type 1, the gene is not the problem. People with blood group O have lower levels; the sugar that denotes blood groups is similar to the one on VWF.
Genetic mutations have been found for type 2, but hardly any for type 1. Not all type 3s are the result of two type 1 parents. In countries where people marry first cousins, type 3 is more common. In type 1, VWF increases every decade so it's vital GPs refer young women with bleeding disorders.
Professor Christine Lee
is consultant haematologist,
Royal Free Hospital, London