Establishment of an International Registry of Patients with Inherited FXIII Deficiency.

Inherited factor XIII (FXIII) deficiency is a rare autosomal recessive disorder affecting approximately one out of one to three million people. FXIII deficiency is characterized by a lifelong bleeding tendency, impaired wound healing and spontaneous abortions in females. In 1993, the European Thrombosis Research Organization (ETRO) Working Party on FXIII initiated a Europe-wide questionnaire on inherited FXIII deficiency. Since 2005, the registry has been endorsed by the Factor XIII Subcommittee of the Scientific and Standardization committee (SSC) of the ISTH. The analysis of 104 European patients demonstrated that the most common bleeding symptoms were subcutaneous bleeding (57%) followed by delayed umbilical cord bleeding (56%), muscle hematoma (49%), hemorrhage after surgery (40%), hemarthrosis (36%), and intracerebral bleeding (34%). Prophylactic treatment was initiated in about 70% of all patients. FXIII-B subunit-deficient patients had a milder phenotype than patients with FXIII-A subunit deficiency.The most frequent mutation affecting the F13A gene was a splice site mutation in intron 5 (IVS5-1G>A).This mutation was found in eight (17%) of 46 analyzed families.The haplotype analysis of patients carrying the IVS5-1A allele was consistent with a founder effect. Recently, we created a new FXIII database website (http://www.f13-database.de) with information about FXIII proteins, genes, mutations and polymorphisms. This website also includes a new questionnaire. Information provided by this questionnaire will allow better understanding of the differences of diagnostic and treatment possibilities in various parts of the world, and it will help to understand the impact of reduced FXIII activity in heterozygous relatives and finally, it will generally increase our knowledge on this rare disease. We hope that our initiative to establish a new international FXIII registry will be actively supported by the community involved in caring for FXIII deficient patients.