SMN1 gene copy number analyses for SMA healthy carriers in Italian population

Alessandra Patitucci; Angela Magariello; Carmine Ungaro; Maria Muglia; Francesca L. Conforti; Anna L. Gabriele; Luigi Citrigno; William Sproviero; Rosalucia Mazzei

doi:10.3233/PGE-2012-017

Journal of Pediatric Genetics, Table of Contents

J Pediatr Genet 2012; 01(02): 099-102
DOI: 10.3233/PGE-2012-017

Georg Thieme Verlag KG Stuttgart – New York

SMN1 gene copy number analyses for SMA healthy carriers in Italian population

Alessandra Patitucci

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

,

Angela Magariello

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

,

Carmine Ungaro

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

,

Maria Muglia

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

,

Francesca L. Conforti

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

,

Anna L. Gabriele

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

,

Luigi Citrigno

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

^bDepartment of Neuroscience, Psychiatric and Anesthesiological Sciences, University of Messina, Messina, Italy

,

William Sproviero

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

^cDepartment of Neurology, University “Magna Graecia”, Catanzaro, Italy

,

Rosalucia Mazzei

^aInstitute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy

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Abstract

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Abstract

The routine molecular test for spinal muscular atrophy (SMA) diagnosis is based on the detection of a homozygous deletion of exons 7 and 8 of the telomeric copy of the survival motor neuron gene (SMN1). The presence of the centromeric copy of the SMN gene (SMN2) does not allow the detection of the hemizygous absence of the SMN1 gene, which characterizes the disease carriers. The demand for a quantitative SMN1 test is permanently growing because there is a high incidence of carriers. The disease is severe and to date there are no effective pharmacological treatments. Here, we present a non-radioactive assay based on real time quantitative polymerase chain reaction. We analyzed eight SMA patients, 14 SMA relatives and 50 health individuals from Southern Italy by real time quantitative method in order to identify haploid deletion occurring in SMA carriers. SMN1 copy number was determined by the comparative threshold cycle method (ΔΔCt). The results confirmed the deletion in all homozygous patients and permitted an evaluation of the number of alleles in the healthy carriers. This method is fast, reproducible, and enables us to discriminate carriers from healthy homozygous, which is impossible with normal techniques.

Keywords

SMA - SMN1 - real time PCR - quantitative assay

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