DOUBLE-STRAND CONFORMATION POLYMORPHISM (DSCP) DETECTS 2 POINT MUTATIONS AT CODON-280 (AAC-]ATC) AND AT CODON-431 (TAC-]AAC) OF THE BLOOD-COAGULATION FACTOR-VIII GENE

Hemophilia A is a hereditary, X-linked, bleeding disorder that is caus ed by a defect in the factor VIII gene. Here, we report two novel poin t mutations in the factor VIII gene that result in an aberrant electro phoretic mobility of double strand PCR fragments (double strand confor mation polymorphism, DSCP). In exon 9 a TAC-->AAC mutation at codon 43 1, replacing Tyr by Asn, was observed in a family (A211) with moderate ly severe hemophilia A. A family with mild hemophilia A revealed an A- ->T mutation in codon 280 (exon 7) that results in the replacement of Asn by Ile. One of these two mutations was not detected in an analysis based on single strand conformation polymorphisms (SSCP). At present we have no explanation for the effect of the nucleotide changes on the electrophoretic mobility of double strand DNA. Although DSCP is not a ble to detect all mutations the combination of DSCP analysis with SSCP analysis increases the sensitivity in a screening for factor VIII mut ations.