Attendance: about 100 attendees.

1. Nomenclature

   At an earlier meeting of the Subcommittee a proposal for the recommended terminology concerning blood coagulation factor XIII had been presented and discussed. At that time, the Subcommittee suggested slight modifications and asked L. Muszbek (Hungary) to resubmit the modified version to the Subcommittee for approval. The revised version was presented by L. Muszbek and discussed by the members of the Subcommittee. The proposal consists of three parts, the main points are outlined below:

   1. Nomenclature of blood coagulation factor XIII (FXIII) from different sources.

      Blood coagulation factor XIII present in the plasma (having the tetrameric structure A₂B₂):

      plasma FXIII, (pFXIII)

      Blood coagulation factor XIII present in cells (in platelets, megakaryocytes, monocytes and macrophages and having the dimeric structure A₂):

      cellular FXIII (cFXIII)

      Recombinant cellular factor XIII:

      recombinant FXIII (rFXIII)

   2. Designation of blood coagulation factor XIII subunits.

      Recommended term for the potentially active subunit present both in plasma and cellular FXIII:

      A (FXIII-A)

      Recommended term for the inhibitory subunit present in plasma but not in cellular FXIII and also present as non-complexed free form in the plasma:

      B (FXIII-B)

   c. Designation of activation intermediates and end-products of blood coagulation factor XIII.

   Active form of blood coagulation factor XIII in general:	FXIIIa
   Thrombin-cleaved inactive form of plasma FXIII:	pFXIIIa'
   Thrombin-cleaved inactive form of cellular FXIII:	cFXIIIa'
   Thrombin-cleaved active form of FXIII:	FXIIIa*
   Non-cleaved active form of FXIII:	FXIIIa¡
   Thrombin-cleaved inactive form of subunit A:	A'
   Thrombin-cleaved active form of subunit A:	A*
   Non-cleaved active form of subunit A:	A¡
   Activation peptide cleaved off from the A subunit:	AP-FXIII

   Points (a) and (b) were unanimously approved by Subcommittee members, point (c) was supported by the majority. Regarding point (c), some questioned the need for such a detailed proposal on activation intermediates while the supporters argued that abbreviations for activation intermediates and end-products are already in use in the literature and the lack of accepted terminology causes considerable confusion). L. Muszbek was given the task of preparing the final form of the manuscript which will then be submitted to SSC for vote and publication.

2. Registry of FXIII deficient patients

   A European registry has been set up by the European Thrombosis Research Organization Factor XIII Working Party. The question was whether to expand the European registry to make it a world-wide registry and thus make it a Subcommittee activity.

   R. Seitz (Germany) gave an account of the present stage of the registry and outlined certain points of clinical appearance and supplementation therapy of FXIII deficiency based on the information provided by the survey. H. Mikkola (Finland) presented the results of a comprehensive molecular genetic investigation of FXIII deficient patients that was made possible by the European registry. A. Ichinose (Japan) and P. Board (Australia) provided additional information on FXIII-deficient patients in Japan and Australia, respectively.

   Although a world-wide registry on FXIII-deficient patients did not seem a realistic goal for the near future, the creation of a database on the molecular genetic defects of FXIII-deficient patients was approved by the Subcommittee. A. Inbal (Israel) volunteered to set up the database.

3. Further issues

   R. Ádány (Hungary) reviewed data on the site of synthesis of FXIII subunits and made methodological recommendations for further studies on this area. P. Bishop (USA) presented an animal model of inflammatory bowel diseases which seems to be applicable for studying the beneficial effect of FXIII concentrate in such cases. C. Greenberg (USA) provided data on the use of site-directed mutagenesis in studying structural-functional aspects of FXIII subunits.

Table of Contents.