Identified CTG Repeat Expansions And Autophagy Biomarker In Hereditary Myotonic Dystrophy Type 1

Objective: Myotonic dystrophy type 1(DM1),an autosomal inherited neuromuscular disease,is the most common type of muscular dystrophy in adults.DM1 is primarily characterized by myotonia and skeletal muscle atrophy.The genetic defect of DM1 is caused by an abnormal expansion of CTG trinucleotide repeats in the 3’UTR region of the Myotonic Dystrophy Protein Kinase(DMPK)gene,which is mapped on chromosome 19q13.32.Due to the obvious heterogeneity of DM1 clinical phenotypes,it is easy to cause missed diagnosis or misdiagnosis.Based on DM1 pedigree,this study is dedicated to the exploration of new diagnostic methods for DM1 and bioinformatics analysis of autophagy-related hub gene.Methods: We performed SNP linkage analysis in DM1 pedigree to confirm the mapped of pathogenic gene.Whole Exome Sequencing(WES)was performed to detect and screen potential pathogenic variants.Subsequently,combined with Expansionhunter software,we identified the causative genes in DM1 family.Meanwhile,the repeat expansions were verified by repeat-primed PCR(RP-PCR)technology.Finally,the gene expression profile datasets of DM1 muscle tissues were obtained from the Gene Expression Omnibus database(GEO),and we performed the Weighted Gene Co-Expression network analysis(WGCNA)and RNA-seq sequencing to analyze the autophagy genes associated with DM1.Results: SNP linkage analysis based on family members mapped the disease locus to 19q13.2-q13.43.Combined with Whole Exome Sequencing(WES)and Expansionhunter software,we excluded the causative variants in disease and identified the location of pathogenic gene in the 3’UTR region of DMPK gene,which was further validated by RP-PCR.Performing WGCNA and comprehensive analyses,DAPK1,was screened out with the values of autophagy-related biomarker for DM1,and further validated in vitro using RNA-Seq and RT-PCR.Conclusion: In conclusion,Combing WES and Expansionhunter software,we identified the trinucleotide repeat expansion in DMPK as the causative mutation in DM1 pedigrees.Our study suggested that the combined methodology was an effective method for molecular diagnosis of DM1.Meanwhile,our findings contribute to a comprehensive understanding of DM1 development,particularly from the perspective of autophagy.Treatment targeting DAPK1 and its downstream signaling pathways may be a novel therapeutic target for DM1.