title: Characterization of a polymorphism in the coding sequence of FCN3 resulting in a Ficolin-3 (Hakata antigen) deficiency state.
abstract: Ficolin-3 (Hakata antigen or H-ficolin) is a soluble pattern recognition molecule in the lectin complement pathway. We speculated whether common genetic variations in the FCN3 gene contribute to deficiency of Ficolin-3. The FCN3 gene was sequenced in 237 healthy Danish Caucasians. The relevance of polymorphisms was assessed with antibodies against Ficolin-3 in a novel ELISA system and by production of recombinant Ficolin-3 variants. Ficolin-3 serum profiles were analyzed by SDS-PAGE and western blotting. Ficolin-3 serum concentration varied 10-fold (median, 24microg/ml; range, 3-54microg/ml). Out of several polymorphisms one FCN3+1637delC causing a reading frame shift and a distortion of the C-terminal end of the molecule with an allele frequency of 0.011 was particularly interesting. In individuals heterozygous for the FCN3+1637delC deletion lowered Ficolin-3 concentration was observed (P=0.025). SDS-PAGE and western blotting of serum revealed a weak band corresponding to the truncated molecule in addition to the normal Ficolin-3 pattern. Characterization of recombinant Ficolin-3 derived from FCN3+1637delC showed that in the homozygous situation this allelic variant would lead to Ficolin-3 deficiency. In conclusion an FCN3+1637delC deletion variant disrupting the possibility for pattern recognition was detected. Characterization of recombinant variant Ficolin-3 shows that homozygosity for the FCN3+1637delC deletion may lead to Ficolin-3 deficiency and may thus be the basis for a novel complement deficiency state.
authors.affiliation: Department of Clinical Immunology, University of Copenhagen, 2100 Copenhagen, Denmark.
authors.forename: Lea
authors.initials: L
authors.lastname: Munthe-Fog
authors.forename: Tina
authors.initials: T
authors.lastname: Hummelshøj
authors.forename: Ying Jie
authors.initials: YJ
authors.lastname: Ma
authors.forename: Bjarke E
authors.initials: BE
authors.lastname: Hansen
authors.forename: Claus
authors.initials: C
authors.lastname: Koch
authors.forename: Hans O
authors.initials: HO
authors.lastname: Madsen
authors.forename: Karsten
authors.initials: K
authors.lastname: Skjødt
authors.forename: Peter
authors.initials: P
authors.lastname: Garred
mesh_terms: D000328:Adult; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005091:Exons; D006023:Glycoproteins / Q000097:blood / Q000172:deficiency* / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D037102:Lectins / Q000097:blood / Q000172:deficiency* / Q000235:genetics*; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: C109662:FCN3 protein, human; D006023:Glycoproteins; D037102:Lectins; D011994:Recombinant Proteins