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Gonzalez Castillo et al. J Transl Genet Genom. 2025;9:338-51 https://dx.doi.org/10.20517/jtgg.2025.57 Page 340

NEW APPROACHES ON DIAGNOSIS
Newborn screening initiatives
As the landscape for Duchenne muscular dystrophy is quickly evolving, new approaches for early diagnosis
are of vital importance.

Newborn screening (NBS) for DMD is fully implemented in China. In the United Kingdom, a long-
standing optional pilot program has been performed in Wales. In December 2019, the U.S. Food and Drug
Administration (FDA) approved an assay using creatine kinase MM (CK-MM) isoform in dried blood test
as a first tier for NBS. However, a second-tier or confirmatory test is necessary [19-24] .

As of now in the United States, two states - Minnesota and Ohio - have both approved and implemented
NBS. Massachusetts, New York and Arizona have approved NBS but have not yet begun screening, while at
least 12 other states have pending legislation .
[25]
NBS provides significant advantages for both patients and their families. It can provide information to guide
future reproductive planning, early access to mutation-targeted therapies (when available), and eligibility for
clinical trials. Despite these advantages, the availability of this program in the United States remains
restricted, with full implementation in only two states which limits the potential for early diagnosis and
treatment.

Long-read sequencing
A variety of molecular techniques have been used to identify causative variants in DMD. Multiplex ligation-
dependent probe amplification (MLPA) is the conventional method used to detect deletions and
duplications, while next generation sequencing (short-read sequencing) can detect small variants and exon
deletions/duplications; collectively, both methods have a diagnostic yield above 95%. Nevertheless,
approximately 2%-7% of cases remain unsolved. Many of these undetected variants are deep intronic
mutations that can generate pseudoexons, microindels, substitutions, large-scale deletions, and duplications.
RNA analysis of muscle tissue might be able to identify some of these mutations; nevertheless, the invasive
nature of this test and clinical availability present significant challenges. Lastly, given the presence of rare
and complex structural variants, a subgroup of patients remains undiagnosed. The introduction of third
generation technologies, long-read sequencing, through several platforms has significant advantages
providing precise identification of structural and complex variants in the DMD gene. Long-read sequencing
is a promising technology with potential to improve diagnostic yield, particularly in cases involving complex
genomic variants [26-29] .

DISEASE MODIFYING TREATMENTS
Primary strategies in Duchenne Muscular Dystrophy treatment include: (1) restoring dystrophin at the
sarcolemma; (2) upregulation of other genes to replace dystrophin, (homologue utrophin); and (3)
managing the downstream effects from the lack of dystrophin which includes inflammation, fibrosis, and
oxidative stress . There are several approaches to increase the expression of dystrophin including viral
[17]
vector mediated gene therapy, exon skipping therapy, read-through of premature stop mutations, and gene
editing, and each has advantages and challenges [see Figures 1 and 2].
[30]
DNA-mediated therapies
Gene editing
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-mediated gene editing is a promising
therapy, theoretically allowing permanent restoration of dystrophin expression. The CRISPR system has