The molecular diagnosis of facioscapulohumeral muscular dystrophy (FSHD) is challenging due to the existence of complex alterations in the 4qter chromosomal region and the genetic heterogeneity of the disease (FSHD1, FSHD2). Hypomethylation, which also plays an important role in the pathophysiology of this condition, is difficult to measure routinely.
- A new technology, based on the use of CRISPR-Cas9 and nanopores, was chosen by Japanese researchers.
- It has enabled the sequencing of very long fragments of genomic DNA, including the D4Z4 repeats, and the simultaneous study of the degree of hypomethylation of these regions of interest.
- The hypomethylation of D4Z4 and the decrease in the number of D4Z4 repeat units is thus confirmed in FSHD1.
- In FSHD2, the size of the D4Z4 region does not vary but the hypomethylation is very important.
This technology should simplify the positive diagnosis of FSHD in molecular biology in the future.
