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Abstract: The homozygous loss of the survival motor neuron 1 (SMN1) gene is the primary cause of spinal muscular atrophy (SMA), a neuromuscular degenerative disease. A genetically similar gene, SMN2, which is not functionally equivalent in all SMA patients, modifies the clinical SMA phenotypes. We analyzed the methylation levels of 4 cpG islands (CGIs) in SMN2 in 35 Chinese children with SMA by MassARRAY. We found that three CpG units located in CGI 1 (nucleotides (nt) −871, −735) and CGI 4 (nt +999) are significantly hypomethylated in SMA type III compared with type I or II children after receiving Bonferroni correction. In addition to the differentially methylated CpG unit of nt −871, the methylation level of the nt −290/−288/−285 unit was negatively correlated with the expression of SMN2 full-length transcripts (SMN2-fl). In addition, the methylation level at nt +938 was inversely proportional to the ratio of SMN2-fl and lacking exon 7 transcripts (SMN2-(7, fl/(7), and was not associated with the SMN2 transcript levels. Thus, we can conclude that SMN2 methylation may regulate the SMA disease phenotype by modulating its transcription.

SMN2基因甲基化与中国儿童型脊肌萎缩症疾病严重程度的相关分析

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[16]List of electronic supplementary materials

[17]Table S1 Primers for SMN2 CGIs cloning sequencing

[18]Table S2 Primers for SMN2 CGIs nested PCR