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This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: clinchem.2009.124958v1 55/7/1415    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Ganesamoorthy, D. Articles by Slater, H. R. PubMed PubMed Citation Articles by Ganesamoorthy, D. Articles by Slater, H. R.

Development of a Multiplex Ligation-Dependent Probe Amplification Assay for Diagnosis and Estimation of the Frequency of Spinocerebellar Ataxia Type 15

¹ Victorian Clinical Genetic Services and Murdoch Children’s Research Institute, University of Melbourne, Department of Paediatrics, Royal Children’s Hospital, Parkville, Victoria, Australia;² Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital Solna, Stockholm, Sweden;³ Department of Medicine, Alfred Hospital, Monash University, Melbourne, Australia;⁴ Genetic Health Services Victoria, Melbourne, Australia;⁵ ANZAC Research Institute, University of Sydney, Department of Medicine, Concord Hospital, Sydney, Australia;

^aaddress correspondence to this author at: VCGS Cytogenetics Laboratory, Royal Children’s Hospital, Parkville VIC 3052, Australia. Fax +61-3- 83416366; e-mail howard.slater{at}ghsv.org.au.

Abstract

Background: Spinocerebellar ataxia type 15 (SCA15) is a slowly progressive neurodegenerative disorder characterized by cerebellar ataxia. Mutation of the ITPR1 gene (inositol 1,4,5-triphosphate receptor, type 1) has been identified recently as the underlying cause, and in most cases the molecular defect is a multiexon deletion. To date, 5 different SCA15 families have been identified with ITPR1 gene deletion.

Methods: We have designed a synthetic, dual-color multiplex ligation-dependent probe amplification (MLPA) assay that measures copy number with high precision in selected exons across the entire length of ITPR1 and the proximal region of the neighboring gene, SUMF1 (sulfatase modifying factor 1). We screened 189 idiopathic ataxic patients with this MLPA assay.

Results: We identified ITPR1 deletion of exons 1–10 in the previously reported AUS1 family (4 members) and deletion of exons 1–38 in a new family (2 members). In addition to the multiexon deletions, apparent single-exon deletions identified in 2 other patients were subsequently shown to be due to single-nucleotide changes at the ligation sites.

Conclusions: The frequency of ITPR1 deletions is 2.7% in known familial cases. This finding suggests that SCA15 is one of the "less common" SCAs. Although the deletions in the 5 families identified worldwide thus far have been of differing sizes, all share deletion of exons 1–10. This region may be important, both in terms of the underlying pathogenetic mechanism and as a pragmatic target for an accurate, robust, and cost-effective diagnostic analysis.