title: Identification and functional analysis of novel calcium-sensing receptor gene mutation in familial hypocalciuric hypercalcemia.
abstract: Familial hypocalciuric hypercalcemia (FHH) is a benign disorder with heterozygous inactivating mutations in the calcium-sensing receptor (CASR) gene. The present study describes the identification and functional analysis of a novel CASR gene mutation leading to FHH. The proband is a 33-yr-old woman (Ca 11.0 mg/dL, intact-PTH 68 pg/mL, FECa 0.17 %). Leukocyte DNA was isolated in four family members and a novel heterozygous mutation (D190G, GAT>GGT) in exon 4 of CASR gene was identified by direct sequence analysis. The mutant CASR expression vector was constructed by mutagenesis procedure and its response to Ca(2+) was characterized by transient transfection into human embryonic kidney (HEK) 293 cells and treatment with increasing extracellular Ca(2+) concentrations. HEK cells didn't activate intracellular signaling (MAPK activation) in response to increases of extracellular Ca(2+) concentrations when the mutant receptor was expressed normally at the cell surface. The novel heterozygous mutation (D190G) identified in the present study showed that the reduction of activity of CASR to extracellular Ca(2+) caused FHH in patients and our study demonstrated the importance of Asp-190 participated in response to Ca(2+) in CASR.
authors.affiliation: Department of Medicine II, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nanjo
authors.forename: So
authors.initials: S
authors.lastname: Nagai
authors.forename: Chikara
authors.initials: C
authors.lastname: Shimizu
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tajima
authors.forename: Takuma
authors.initials: T
authors.lastname: Kondo
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Narihito
authors.initials: N
authors.lastname: Yoshioka
authors.forename: Takao
authors.initials: T
authors.lastname: Koike
mesh_terms: D000328:Adult; D002118:Calcium / Q000494:pharmacology / Q000652:urine; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D006934:Hypercalcemia / Q000235:genetics*; D006961:Hyperparathyroidism / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D044169:Receptors, Calcium-Sensing / Q000235:genetics* / Q000502:physiology; D014162:Transfection
chemical_list: D044169:Receptors, Calcium-Sensing; D002118:Calcium