SMN1 gene copy number analyses for SMA healthy carriers in Italian population.
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.
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Alessandra
A
Patitucci
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Angela
A
Magariello
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Carmine
C
Ungaro
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Maria
M
Muglia
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Francesca L
FL
Conforti
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Anna L
AL
Gabriele
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy; Department of Neuroscience, Psychiatric and Anesthesiological Sciences, University of Messina, Messina, Italy.
Luigi
L
Citrigno
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy; Department of Neurology, University "Magna Graecia", Catanzaro, Italy.
William
W
Sproviero
Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy.
Rosalucia
R
Mazzei
SMA; SMN1; quantitative assay; real time PCR