An abnormal fibrinogen with delayed fibrinopeptide A release.

Investigation of the family of a patient presenting with haematuria revealed seven cases in three generations showing a prolonged thrombin clotting time. A dysfibrinogenaemia was confirmed when purified fibrinogen from an affected member of the family was shown to also exhibit a prolonged thrombin clotting time. No molecular abnormality could be demonstrated using electrophoretic and immunological techniques. However, using a specific radioimmunoassay to fibrinopeptide A a major defect has been localized to a delay in the rate of release of this peptide by thrombin when the abnormal fibrinogen is converted to fibrin. This case of dysfibrinogenaemia has been tentatively designated fibrinogen Manchester.