title: Somatic mosaicism and compound heterozygosity in female hemophilia B.
abstract: Sequencing the complete factor IX gene of 2 sisters with hemophilia B with different phenotypes and no family history of hemorrhagic diathesis revealed a common 5' splice site mutation in intron 3 (T6704C) in both and an additional missense mutation (I344T) in one. The presence of dysfunctional antigen in the latter strongly suggested that these mutations are in trans. Neither mutation was found in leukocyte DNA from the asymptomatic parents, but the mother was in somatic mosaicism for the shared splice site mutation. This case illustrates the importance of defining the phenotype and considering somatic mosaicism in sporadic cases. It underlines the limitations of complete gene sequencing for the detection of mosaicism and has implication for genetic counseling. (Blood. 2000;96:1585-1587)
authors.affiliation: American Hospital of Paris, Neuilly, France.
authors.forename: J M
authors.initials: JM
authors.lastname: Costa
authors.forename: D
authors.initials: D
authors.lastname: Vidaud
authors.forename: I
authors.initials: I
authors.lastname: Laurendeau
authors.forename: M
authors.initials: M
authors.lastname: Vidaud
authors.forename: E
authors.initials: E
authors.lastname: Fressinaud
authors.forename: J P
authors.initials: JP
authors.lastname: Moisan
authors.forename: A
authors.initials: A
authors.lastname: David
authors.forename: D
authors.initials: D
authors.lastname: Meyer
authors.forename: J M
authors.initials: JM
authors.lastname: Lavergne
mesh_terms: D000293:Adolescent; D005164:Factor IX / Q000235:genetics*; D005260:Female; D002836:Hemophilia B / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D009030:Mosaicism; D009154:Mutation
chemical_list: D005164:Factor IX