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Compound Heterozygosity for Null Mutations and a Common Hypomorphic Risk Haplotype in TBX6 Causes Congenital Scoliosis
Author(s) -
Takeda Kazuki,
Kou Ikuyo,
Kawakami Noriaki,
Iida Aritoshi,
Nakajima Masahiro,
Ogura Yoji,
Imagawa Eri,
Miyake Noriko,
Matsumoto Naomichi,
Yasuhiko Yukuto,
Sudo Hideki,
Kotani Toshiaki,
Nakamura Masaya,
Matsumoto Morio,
Watanabe Kota,
Ikegawa Shiro
Publication year - 2017
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.23168
Subject(s) - compound heterozygosity , haplotype , null allele , biology , genetics , locus (genetics) , loss of heterozygosity , missense mutation , allele , mutation , gene
Congenital scoliosis (CS) occurs as a result of vertebral malformations and has an incidence of 0.5–1/1,000 births. Recently, TBX6 on chromosome 16p11.2 was reported as a disease gene for CS; about 10% of Chinese CS patients were compound heterozygotes for rare null mutations and a common haplotype defined by three SNPs in TBX6 . All patients had hemivertebrae. We recruited 94 Japanese CS patients, investigated the TBX6 locus for both mutations and the risk haplotype, examined transcriptional activities of mutant TBX6 in vitro, and evaluated clinical and radiographic features. We identified TBX6 null mutations in nine patients, including a missense mutation that had a loss of function in vitro. All had the risk haplotype in the opposite allele. One of the mutations showed dominant negative effect. Although all Chinese patients had one or more hemivertebrae, two Japanese patients did not have hemivertebra. The compound heterozygosity of null mutations and the common risk haplotype in TBX6 also causes CS in Japanese patients with similar incidence. Hemivertebra was not a specific type of spinal malformation in TBX6 ‐associated CS (TACS). A heterozygous TBX6 loss‐of‐function mutation has been reported in a family with autosomal‐dominant spondylocostal dysostosis, but it may represent a spectrum of the same disease with TACS.