Molecular diagnosis of puerile spinal muscular atrophy (with report of 10 cases) / 解放军医学杂志

ABSTRACT

Objective To make molecular diagnosis for puerile spinal muscular atrophy(SMA).Methods Genomic DNA was extracted directly from the blood of both the case group(10 children with SMA) and the control group(including 19 parents of SMA patients and 20 healthy individuals).Two methods,polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and allele-specific PCR,were used to analyze exon 7 of SMN gene from genomic DNA,and consequent electrophoresis of PCR products on agarose gel was performed.Results Genotyping results obtained by both methods were in complete agreement for all of the samples analyzed.In conventional PCR-RFLP,part of the PCR products(189bp) from genomic DNA of all 39 members in the control group remained intact after digestion with Dra I,while the PCR products from genomic DNA of all 10 SMA children in the case group was completely digested by Dra I.In allele-specific PCR,exon 7 of both SMN1 and SMN2 could be seen when genomic DNA of all 39 members in the control group was used,while only SMN2's exon 7 could be seen when genomic DNA of all 10 SMA children in the case group was used.Conclusion Homozygous deletion of SMN1 was present in all 10 SMA children in the case group,while homozygous deletion of SMN1 was not detected in all 39 members in the control group.The combination of PCR-RFLP and allele-specific PCR,both their results can be references for each other,offers efficient and accurate methodology for molecular diagnosis of SMA.