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Functional characterization of missense variants in the creatine transporter gene ( SLC6A8 ): improved diagnostic application
Author(s) -
Rosenberg Efraim H.,
Martínez Muñoz Cristina,
Betsalel Ofir T.,
van Dooren Silvy J.M.,
Fernandez Matilde,
Jakobs Cornelis,
deGrauw Ton J.,
Kleefstra Tjitske,
Schwartz Charles E.,
Salomons Gajja S.
Publication year - 2007
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.20532
Subject(s) - missense mutation , biology , genetics , gene , creatine , exon , microbiology and biotechnology , mutation , biochemistry
Abstract Creatine transporter deficiency is an X‐linked mental retardation disorder caused by mutations in the creatine transporter gene ( SLC6A8 ). So far, 20 mutations in the SLC6A8 gene have been described. We have developed a diagnostic assay to test creatine uptake in fibroblasts. Additionally, we expanded the assay to characterize novel SLC6A8 missense variants. A total of 13 variants were introduced in the SLC6A8 cDNA by site‐directed mutagenesis. All variants were transiently transfected in SLC6A8‐deficient fibroblasts and tested for restoration of creatine uptake in deficient primary fibroblasts. Thus, we proved that nine variants (p.Gly87Arg, p.Phe107del, p.Tyr317X, p.Asn336del, p.Cys337Trp, p.Ile347del, p.Pro390Leu, p.Arg391Trp, and p.Pro554Leu) are pathogenic mutations and four variants (p.Lys4Arg, p.Gly26Arg, p.Met560Val, and p.Val629Ile) are nonpathogenic. The present study provides an improved diagnostic tool to classify sequence variants of unknown significance. Hum Mutat 28(9), 890–896, 2007. © 2007 Wiley‐Liss, Inc.