Abstract: Abstract Objective To perform gene diagnosis for 30 suspected patients of spinal muscular atrophy (SMA) using multiplex ligation dependent probe amplification (MLPA) and PCR-restriction fragment length polymorphism (PCR-RFLP), and compare the results of the two methods. Method Genomic DNA was isolated from peripheral blood of each subject from 30 families using salting-out method．DNA concentration was determined by nucleic acid quantitative instrument. Exon 7 and 8 of SMN gene was amplified by allele specific PCR.The PCR products were digested with DraⅠand DdeⅠ, detected by agarose gel electrophoresis. Simultaneously,the DNA samples were analyzed by SALSA MLPA KIT P021. Results Both PCR-RFLP and MLPA analysis showed the same that 22 patients with exon 7 and 8 homozygous deletion, and 2 patients with only exon 7 homozygous deletion of SMN1. The other 6 cases and parents presented no homozygous deletion by PCR-RFLP, but one child and two morthers of them were detected heterozygous by MLPA. Also MLPA analysis found three “2+0”carriers from 3 families. The data also showed that the SMN2 copy numbers were mainly 4 or 5 in SMA patients, while the carriers and the normal individuals were 2 or 3 and 1 or 2 copies respectively. There were clear statistical significance in the groups of patient -carrier and patient-normal individuals ( p<0.001). The carrier -normal group appeared no statistical significance( p>0.05). Conclution Compared with PCR-RFLP, MLPA is more convenient, precise, high-effective, and it can accuratly quantitative SMN1 and SMN2, so it is a kind of technique of gene diagnosis for common genetic disease .

Key words: Spinal muscular atrophy, MLPA, PFLP, SMN gene, Gene diagnosis