title: Mild haemophilia B from a novel missense mutation Ser350Ala of the F9 gene.
abstract: Haemophilia B is an X-linked recessive bleeding disorder caused by mutations in the F9 gene on Xq27.1, which lead to deficient coagulation factor IX (FIX). The mild form of haemophilia B has been known to be underdiagnosed due to mild clinical symptoms and minimally prolonged activated partial thromboplastin time. We herein describe a sporadic case of mild haemophilia B from a novel missense mutation of F9. The proband was a 4-year-old boy with a mild bleeding history. He had no family history of bleeding tendency. Coagulation screening tests revealed prolonged aPTT at 42.6s (STA-PTT Automate, reference range, 29.1-41.9s) and a decreased FIX activity at 13% in factor assays. Molecular genetic analysis of F9 revealed that he was hemizygous for a missense mutation, c.1048T>G (p.Ser350Ala), which has not been reported previously. His mother was a carrier of the mutation. This case represents a novel missense mutation from non-CpG transversion of F9.
authors.affiliation: Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Chang-Hun
authors.initials: CH
authors.lastname: Park
authors.forename: Ja-Young
authors.initials: JY
authors.lastname: Seo
authors.forename: Sun-Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Hong Hoe
authors.initials: HH
authors.lastname: Koo
authors.forename: Hee-Jin
authors.initials: HJ
authors.lastname: Kim
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D002675:Child, Preschool; D005164:Factor IX / Q000737:chemistry / Q000235:genetics*; D005260:Female; D057898:Hemizygote; D002836:Hemophilia B / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010314:Partial Thromboplastin Time; D012694:Serine
chemical_list: D012694:Serine; D005164:Factor IX; D000409:Alanine