Hemophilia A

Abstract

To understand the molecular basis of hemophilia A and to provide heterozygote detection and prenatal diagnosis by DNA analysis, we used cloned factor VIII:C DNA fragments to study 10 affected families. In four of these families, inhibitors of factor VIII:C had developed in affected persons. In one such family a deletion of approximately 80 kb within the factor VIII:C gene was identified. Carriers of the deletion were identified through detection of an abnormal DNA fragment located at the deletion end points. In another family a single nucleotide change in the coding region of the factor VIII:C gene produced a nonsense codon leading to premature termination of factor VIII:C synthesis. Carrier detection was performed in eight female members of this four-generation family. In a third family a small change in the size of a restriction-endonuclease fragment correlated with the presence of the mutant gene, and in the other seven families the molecular defect has not yet been identified. In addition, we used two common polymorphic sites in the factor VIII:C gene to differentiate the normal from the defective gene in four of six obligate female carriers from families with patients in whom inhibitors did not develop. Carrier detection was possible in other members of these families. These data suggest that DNA analysis of the factor VIII:C gene provides an accurate method of carrier detection and, potentially, of prenatal diagnosis in at least 50 per cent of the pedigrees affected by hemophilia A.

Restriction fragment length polymorphisms of X chromosome among Japanese population

“…Figure 1 shows the polymorphic probes for X chromosome so far studied in the Japanese, which cover from pter to qter regions of the chromosome. Similar systematic studies of polymorphic probes for autosomes are absolutely needed for linkage analysis in Japan, though there have been not a few reports on the ethnic differences (Prochownik et al, 1983;Antonarakis et al, 1985;Haneda et al, 1986;Wainscoat et al, 1986;Lubahn et aI., 1987;Suzuki et al, 1988;Suehiro et al, 1988;Ogasawara, 1988).…”

RFLPs of factor IX gene in Japanese haemophilia B families and gene deletion in two high-responder-inhibitor patients

“…Restriction enzymes such as TaqI are a useful marker to search for a point mutation, and several point mutations were reported in haemophilia A patients detected by the method of RFLP search (Antonarakis et al, 1985;Gitscher et al, 1985;Gitscher et al, 1986). In haemophilia B genes, a definitive mutation point has not been found by screening using restriction enzymes.…”

A deletion involving intron 13 and exon 14 of factor VIII gene in a haemophiliac with anti-factor VIII antibody

“…Briefly, (1) probe A, 1.7 kbp long, delineates exons 1-12, (2) probe B, 4.7 kbp long, delineates exons 14-26, (3) probe C, 1.8 kbp, contains the remaining portion of exon 26, (4) probe D, 0.37 kpb, contains the portion of exon 14 between EcoRI and PstI sites at positions 2290 and 2658, respectively, (5) probe E, 2.5 kbp, contains another portion of exon 14 between two PstI sites at positions 2659 and 5163. The probes A, B and C are contained in pSP64, Ap g (Antonarakis et al, 1985), kindly provided by Dr. Lewis, Genetics Institute, whilst probes D and E are contained in pHSG398, Cm ~ (Takeshita et al, 1987).…”

“…The genetic heterogeneity of haemophilia patients suggests that many different molecular alterations are involved in the resultant malfunctional factor VIII gene in haemophiliacs. Several point and deletion mutations in the factor VIII gene were observed in Caucasian population (Gitschier et al, 1985(Gitschier et al, , 1986Antonarakis et al, 1985;Youssoufian et al, 1986Youssoufian et al, , 1987aYoussoufian et al, , 1987bHiguchi et al, 1987;Bernardi et aL, 1987;Matthews et al, 1987).…”