title: Point mutations in four hemophilia B patients from China.
abstract: Point mutations in factor IX genes of four unrelated Chinese patients with hemophilia B have been identified by direct sequencing of amplified genomic DNA fragments. These four mutations occur in exon 8 of the factor IX gene. A C to T transition at nucleotide 30,863 changes codon 248 from Arg (CGA) to a new Stop codon (TGA), described in a previous family as factor IXMalmo3 (Green P M et al., EMBO J 1989; 8: 1067). A G to A transition at nucleotide 31,051 changes codon 310 from Trp (TGG) to a nonsense or Stop codon (TGA; factor IXChongquing2). A G to A transition at nucleotide 31,119 changes codon 333 which is for Arg (CGA) in normal factor IX, to one for Gln (CAA) in the variant previously described as factor IXLondon2 (Tsang T C et al., EMBO J 1988; 7: 3009) in a patient with moderately severe hemophilia B. The fourth patient has a novel C to A transversion at nucleotide 31,290, which corresponds to replacement of codon 390 which is for Ala (GCA) in normal factor IX, to one for Glu (GAA) in a patient with moderately severe hemophilia B (factor IXChongquing3). DNA sequences of amplified fragments from mothers of three showed both their son's variant and a normal nucleotide at the appropriate position, indicating that they are carriers. The fourth patient's (factor IXMalmo3) mother, whose DNA was not evaluable, was most probably a carrier because of her low plasma factor IX levels.
authors: Department of Pediatrics, University of Washington, Seattle.
authors: N S
authors: NS
authors: Wang
authors: S H
authors: SH
authors: Chen
authors: A R
authors: AR
authors: Thompson
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D002681:China; D004252:DNA Mutational Analysis; D005091:Exons; D005164:Factor IX / Q000235:genetics*; D005260:Female; D002836:Hemophilia B / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation
chemical_list: D005164:Factor IX