Comparison of three methods for the genetic diagnosis of spinal muscular atrophy / 中华检验医学杂志

ABSTRACT

Objective To evaluate the value of PCR-restriction fragment length polymorphism (PCR-RFLP),real-time PCR and multiplex ligation-dependent probe amplification (MLPA) in the genetic diagnosis of spinal muscular atrophy (SMA) and make laboratory support accessible to clinicians for the molecular diagnosis of SMA.Methods Methodological evaluation.Forty-one suspected SMA cases and 359 control individuals received in Shanghai Children's Medical Centre from March 2013 to June 2014 were detected for the deletion of exon 7 and 8 in the survival motor neuron gene 1 (SMN 1) by PCR-RFLP,realtime PCR and MLPA,respectively.Then the results of the three methods were compared and the benefits and limitations of the three methods were evaluated.Results The result of real-time PCR was in complete agreement with that of MLPA,showing that 29 suspected cases harbored homozygous deletions of SMN1 and 1 case possessed heterozygous deletion.Among the homozygous deletions,27 patients demonstrated absence of exon 7 and 8,and 2 cases demonstrated only the absence of exon 7.Meanwhile,both PCR-RFLP and MLPA analysis showed the same results that only 5 out of 395 control cases carried heterozygous deletion.As for cases without heterozygous deletions,PCR-RFLP demonstrated the same result with real-time PCR and MLPA but it missed all the heterozygous ones.Conclusions PCR-RFLP,the conventional SMA gene diagnosis method,was only capable of detecting homozygous deletion of exon 7 and/or 8 of SMN1,but was not as sensitive as to find out the carriers with heterozygous deletions.MLPA could detect the deletion and quantify the copy numbers of exon 7 and 8 of SMN1,efficiently,while the price was relatively high,which brings challenges for its application in the carrier screening of SMA.Compared with these two methods,realtime PCR with high throughput and low input was a rapid,acourate and economic method for the genetic diagnosis of SMA and carrier screening in large populations.