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Eur J Hum Genet. 2015 May;23(5):633-8. doi: 10.1038/ejhg.2014.109. Epub 2014 Jun 11.

Missense variant in CCDC22 causes X-linked recessive intellectual disability with features of Ritscher-Schinzel/3C syndrome.

Author information

1
1] Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany [2] Max Planck Institute for Molecular Genetics, Berlin, Germany.
2
Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Berlin, Germany.
3
Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland.
4
Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany.
5
Division of Child Neurology, University Children's Hospital Zurich, Zürich, Switzerland.
6
Department of Pediatrics, Medical University Graz, Graz, Austria.
7
Institute of Human Genetics, Medical University of Graz, Graz, Austria.
8
1] Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany [2] Max Planck Institute for Molecular Genetics, Berlin, Germany [3] Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Berlin, Germany.

Abstract

Ritscher-Schinzel syndrome (RSS)/3C (cranio-cerebro-cardiac) syndrome (OMIM#220210) is a rare and clinically heterogeneous developmental disorder characterized by intellectual disability, cerebellar brain malformations, congenital heart defects, and craniofacial abnormalities. A recent study of a Canadian cohort identified homozygous sequence variants in the KIAA0196 gene, which encodes the WASH complex subunit strumpellin, as a cause for a form of RSS/3C syndrome. We have searched for genetic causes of a phenotype similar to RSS/3C syndrome in an Austrian family with two affected sons. To search for disease-causing variants, whole-exome sequencing (WES) was performed on samples from two affected male children and their parents. Before WES, CGH array comparative genomic hybridization was applied. Validation of WES and segregation studies was done using routine Sanger sequencing. Exome sequencing detected a missense variant (c.1670A>G; p.(Tyr557Cys)) in exon 15 of the CCDC22 gene, which maps to chromosome Xp11.23. Western blots of immortalized lymphoblastoid cell lines (LCLs) from the affected individual showed decreased expression of CCDC22 and an increased expression of WASH1 but a normal expression of strumpellin and FAM21 in the patients cells. We identified a variant in CCDC22 gene as the cause of an X-linked phenotype similar to RSS/3C syndrome in the family described here. A hypomorphic variant in CCDC22 was previously reported in association with a familial case of syndromic X-linked intellectual disability, which shows phenotypic overlap with RSS/3C syndrome. Thus, different inactivating variants affecting CCDC22 are associated with a phenotype similar to RSS/3C syndrome.

PMID:
24916641
PMCID:
PMC4402616
DOI:
10.1038/ejhg.2014.109
[Indexed for MEDLINE]
Free PMC Article
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