title: Spinal muscular atrophy genotyping by gene dosage using multiple ligation-dependent probe amplification.
abstract: Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by degeneration of the anterior horn cells of the spinal cord, causing symmetric proximal muscle weakness. SMA is classified in three clinical types, SMA I, SMA II, and SMA III, based on the severity of the symptoms and the age of onset. About 95% of SMA cases are caused by homozygous deletion of the survival motor neuron 1 (SMN1) gene (5q13), or its conversion to SMN2. The molecular diagnosis of this disease is usually carried out by a polymerase chain reaction-restriction fragment length polymorphism approach able to evidence the absence of both SMN1 copies. However, this approach is not able to identify heterozygous healthy carriers, which show a very high frequency in general population (1:50). We used the multiple ligation-dependent probe amplification (MLPA) approach for the molecular diagnosis of SMA in 19 affected patient and in 57 individuals at risk to become healthy carriers. This analysis detected the absence of the homozygous SMN1 in all the investigated cases, and allowed to discriminate between SMN1 deletion and conversion to SMN2 on the basis of the size showed by the peaks specific for the different genes mapped within the SMA critical region. Moreover, MLPA analysis evidenced a condition of the absence of the heterozygous SMN1 in 33 out of the 57 relatives of the affected patients, demonstrating the usefulness of this approach in the identification of healthy carriers. Thus, the MLPA technique represents an easy, low cost, and high throughput system in the molecular diagnosis of SMA, both in affected patients and in healthy carriers.
authors.affiliation: Dipartimento di Scienze Biomediche, Sezione di Genetica Medica, Università G. dAnnunzio, Via dei Vestini 35, Chieti-Pescara, 66013, Italy.
authors.forename: Oronzo
authors.initials: O
authors.lastname: Scarciolla
authors.forename: Liborio
authors.initials: L
authors.lastname: Stuppia
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: De Angelis
authors.forename: Stefania
authors.initials: S
authors.lastname: Murru
authors.forename: Chiara
authors.initials: C
authors.lastname: Palka
authors.forename: Rossella
authors.initials: R
authors.lastname: Giuliani
authors.forename: Marta
authors.initials: M
authors.lastname: Pace
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Muzio
authors.forename: Isabella
authors.initials: I
authors.lastname: Torrente
authors.forename: Annunziata
authors.initials: A
authors.lastname: Morella
authors.forename: Paola
authors.initials: P
authors.lastname: Grammatico
authors.forename: Manlio
authors.initials: M
authors.lastname: Giacanelli
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Rosatelli
authors.forename: Antonino
authors.initials: A
authors.lastname: Uncini
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallapiccola
mesh_terms: D000328:Adult; D000368:Aged; D015342:DNA Probes; D018628:Gene Dosage; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D012150:Polymorphism, Restriction Fragment Length; D012307:Risk Factors; D014897:Spinal Muscular Atrophies of Childhood / Q000453:epidemiology / Q000235:genetics*
chemical_list: D015342:DNA Probes