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Novel intragenic duplications and mutations of CASK in patients with mental retardation and microcephaly with pontine and cerebellar hypoplasia (MICPCH)


The CASK gene encoding a member of the membrane-associated guanylate kinase protein family is highly expressed in the mammalian nervous system of both adults and fetuses, playing several roles in neural development and synaptic function. Recently, CASK aberrations caused by both mutations and deletions have been reported to cause severe mental retardation (MR), microcephaly and disproportionate pontine and cerebellar hypoplasia (MICPCH) in females. Here, mutations and copy numbers of CASK were examined in ten females with MR and MICPCH, and the following changes were detected: nonsense mutations in three cases, a 2-bp deletion in one case, mutations at exon–intron junctions in two cases, heterozygous deletions encompassing CASK in two cases and interstitial duplications in two cases. Except for the heterozygous deletions, each change including the intragenic duplications potentially caused an aberrant transcript, resulting in CASK null mutations. The results provide novel mutations and copy number aberrations of CASK, causing MR with MICPCH, and also demonstrate the similarity of the phenotypes of MR with MICPCH regardless of the CASK mutation.

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We thank Ayako Takahashi and Rumi Mori for technical assistance. This study was supported by the Joint Usage/Research Program of Medical Research Institute, Tokyo Medical and Dental University. This work was also supported by Grants-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science, and Technology, Japan; a grant from Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology Corporation (JST); a grant from the New Energy and Industrial Technology Development Organization (NEDO).

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Correspondence to Johji Inazawa.

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Hayashi, S., Okamoto, N., Chinen, Y. et al. Novel intragenic duplications and mutations of CASK in patients with mental retardation and microcephaly with pontine and cerebellar hypoplasia (MICPCH). Hum Genet 131, 99–110 (2012).

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