Ulf Birkedal from Copenhagen University Hospital in Denmark spoke at the Nanopore Community Meeting in 2021 about “Nanopore sequencing increases resolution of DMPK hypermethylation in myotonic dystrophy type 1 patients.” Myotonic Dystrophy Type 1 (DM1), explained Birkedal, is an autosomal dominant multisystem disorder. Muscle degeneration, weakness, and myotonia are the symptoms, and Birkedal noted that it is the most common muscular dystrophy in adults. The DMPK gene on chromosome 18 has altered transcription level in this disease. The altered transcript becomes toxic in disease. DM1 diagnostics has been done by Southern blotting and is now replaced by a sensitive triplet primer PCR. The repeat is unstable and interruptions can be observed. Expansion of the repeat can be detected by PCR. For this study, they selected patients and controls. They used Cas9 enrichment and R9.4.1 flowcells. To assess repeat length, they used STRique. The team used Megalodon, Nanopolish, and DeepSignal to assess methylation. They concluded that Nanopore sequencing is “useful to investigate both CTG repeats and methylation status in DMA1 patients” and “methylation and repeat status can be analyzed on single molecule level.”
