title: Enhanced exon 2 skipping caused by c.910G>A variant and alternative splicing of MEFV genes in two independent cases of familial Mediterranean fever.
abstract: Most reported cases of familial Mediterranean fever (FMF) involve missense mutations of MEFV concentrated within exon 10. We experienced two independent pedigrees of a unique variant in the MEFV gene that might cause excessive exon 2 skipping due to enhanced alternative splicing. In this study, we tried to elucidate the molecular mechanism of the MEFV variant as a cause of the FMF phenotype. Peripheral blood was obtained from volunteers and two patients with homozygous c.910G>A variant of the MEFV gene. MEFV messenger RNA (mRNA) expression patterns in mononuclear cells and granulocytes were compared using forward and reverse primers from exons 1 and 3, respectively. Expression profiles of pyrin were examined by transfecting wild-type and variant MEFV genes into HEK293T cells. Expression of normal-sized mRNA was extremely reduced in these patients, whereas that of aberrant short mRNA, deleting exon 2 (Δex2), was significantly increased. Immunohistochemical and immunoblotting analyses revealed a truncated immunoreactive pyrin protein in cells transfected with Δex2 cDNA. The MEFV gene c.910G>A variant results in accelerated aberrant splicing with abnormal protein size, presumably leading to anomalous pyrin function. This is the first report to show that an MEFV variant other than missense mutation is responsible for the FMF phenotype.
authors.affiliation: Department of Pediatrics, School of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Tone
authors.forename: Tomoko
authors.initials: T
authors.lastname: Toma
authors.forename: Akiko
authors.initials: A
authors.lastname: Toga
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Sakakibara
authors.forename: Taizo
authors.initials: T
authors.lastname: Wada
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yabe
authors.forename: Hiromitu
authors.initials: H
authors.lastname: Kusafuka
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yachie
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D019943:Amino Acid Substitution; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics*; D010505:Familial Mediterranean Fever / Q000097:blood / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D006098:Granulocytes / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D017354:Point Mutation; D020641:Polymorphism, Single Nucleotide; D000071198:Pyrin; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D003598:Cytoskeletal Proteins; D008070:Lipopolysaccharides; C000604192:MEFV protein, human; D000071198:Pyrin; D012333:RNA, Messenger; D007371:Interferon-gamma