title: Identification and functional analysis of a novel CaSR mutation in a family with familial hypocalciuric hypercalcemia.
abstract: The calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that plays an essential role in maintaining calcium homeostasis. In the present study, we analyzed the CaSR gene in a Korean family with familial hypocalciuric hypercalcemia (FHH). Genetic studies were performed by direct sequence analysis of the CaSR gene in genomic DNA obtained from peripheral leukocytes. A novel heterozygous G to T substitution at nucleotide position 1711 in exon 6, resulting in the G571W mutation, was identified in the CaSR gene in a 26-year-old female with asymptomatic hypercalcemia, a low calcium/creatinine clearance ratio, and normal intact parathyroid hormone. To study CaSR expression, the mutation was introduced by site-directed mutagenesis into a wild-type (WT) CaSR-expressing pCR3.1 vector, and COS-7 cells were transfected with either the WT or mutant CaSR-containing vector. Transfected cells loaded with Fura-2/AM, a fluorescent indicator of Ca2+, were assessed for CaSR function by the change in intracellular calcium [as measured by the 340 nm/380 nm fluorescence intensity ratio (F340/F380)] made in response to challenge with extracellular Ca2+. Both WT and G571W cells had equivalent amounts of CaSR protein in the cell membrane. However, after challenge with extracellular Ca2+, cells transfected with G571W CaSR responded with a lower F340/F380 ratio than those transfected with WT CaSR and showed decreased sensitivity to extracellular Ca2+concentrations. The G571W mutation had therefore impaired the CaSR function. In conclusion, we identified a novel loss-of-function mutation, G571W, in the CaSR gene in a Korean family with FHH.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea.
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea.
authors.forename: Su Yeon
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea.
authors.forename: Je Ho
authors.initials: JH
authors.lastname: Han
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Uijungbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Republic of Korea. imsts@catholic.ac.kr.
authors.forename: Tae Seo
authors.initials: TS
authors.lastname: Sohn
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Uijungbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Republic of Korea.
authors.forename: Hyun Shik
authors.initials: HS
authors.lastname: Son
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 56 Dongsoo-ro, Bupyeong-gu, Incheon, 403-720, Republic of Korea. sungdaem@gmail.com.
authors.forename: Sung-Dae
authors.initials: SD
authors.lastname: Moon
mesh_terms: D000328:Adult; D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002522:Chlorocebus aethiops; D005190:Family; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D006934:Hypercalcemia / Q000151:congenital* / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D044169:Receptors, Calcium-Sensing / Q000096:biosynthesis / Q000235:genetics*; D056910:Republic of Korea
chemical_list: C095550:CASR protein, human; D044169:Receptors, Calcium-Sensing; D002118:Calcium
keywords: Autosomal dominant; Calcium-sensing receptor; Familial hypocalciuric hypercalcemia