Heterogeneity of the factor IX locus in nine hemophilia B inhibitor patients.

R J Matthews; D S Anson; I R Peake; A L Bloom

doi:10.1172/JCI112880

Heterogeneity of the factor IX locus in nine hemophilia B inhibitor patients.

R J Matthews, D S Anson, I R Peake, and A L Bloom

Published March 1, 1987 - More info

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Abstract

DNA from nine hemophilia B patients who produce anti-factor IX inhibitors (antibodies), including two brothers, was analyzed by the Southern blotting method and hybridization with factor IX cDNA, intragenomic, and 3'-flanking probes. Two inhibitor patients were shown to have total deletions of the factor IX gene. Two other inhibitor patients, the brothers, were shown to have a presumably identical complex rearrangement of the factor IX gene involving two separate deletions. The first deletion is of approximately 5.0 kb and removes exon e. The second deletion is between 9 and 29 kb and removes exons g and h but leaves exon f intact. An abnormal Taq I fragment at one end of the deletion junctions acted as a marker for the inheritance of hemophilia B in the patients' family. Five other inhibitor patients have a structurally intact factor IX gene as detected by this method. Our studies indicate that whereas large structural factor IX gene defects predispose hemophilia B patients to developing an anti-factor IX inhibitor, the development of an inhibitor can be associated with other defects of the factor IX gene.

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