Dystrophinopathy Phenotypes and Modifying Factors in DMD Exon 45-55 Deletion.

OBJECTIVE: Duchenne muscular dystrophy (DMD) exon 45-55 deletion (del45-55) has been postulated as a model that could treat up to 60% of DMD patients, but the associated clinical variability and complications require clarification. We aimed to understand the phenotypes and potential modifying factors of this dystrophinopathy subset. METHODS: This cross-sectional, multicenter cohort study applied clinical and functional evaluation. Next generation sequencing was employed to identify intronic breakpoints and their impact on the Dp140 promotor, intronic long noncoding RNA, and regulatory splicing sequences. DMD modifiers (SPP1, LTBP4, ACTN3) and concomitant mutations were also assessed. Haplotypes were built using DMD single nucleotide polymorphisms. Dystrophin expression was evaluated via immunostaining, Western blotting, reverse transcription polymerase chain reaction (PCR), and droplet digital PCR in 9 muscle biopsies. RESULTS: The series comprised 57 subjects (23 index) expressing Becker phenotype (28%), isolated cardiopathy (19%), and asymptomatic features (53%). Cognitive impairment occurred in 90% of children. Patients were classified according to 10 distinct index-case breakpoints; 4 of them were recurrent due to founder events. A specific breakpoint (D5) was associated with severity, but no significant effect was appreciated due to the changes in intronic sequences. All biopsies showed dystrophin expression of >67% and traces of alternative del45-57 transcript that were not deemed pathogenically relevant. Only the LTBP4 haplotype appeared associated the presence of cardiopathy among the explored extragenic factors. INTERPRETATION: We confirmed that del45-55 segregates a high proportion of benign phenotypes, severe cases, and isolated cardiac and cognitive presentations. Although some influence of the intronic breakpoint position and the LTBP4 modifier may exist, the pathomechanisms responsible for the phenotypic variability remain largely unresolved. ANN NEUROL 2022;92:793-806.

Effectiveness of teleassistance at improving quality of life in people with neuromuscular diseases.

Rare neuromuscular diseases (NDs) are a group of inherited or acquired neurological pathologies affecting the muscles and the nervous system. Their low prevalence and high geographical dispersion can cause isolation and difficulties in social interaction between affected equals. New technologies, such as videoconferencing, offer a complementary option for improving the health of this population. The purpose of this study was to assess the effectiveness of a teleassistance program at improving health-related quality of life (HRQoL) through social interaction in adults with NDs. The sample consisted of 45 participants affected by rare NDs. Twenty-four participants were assigned to the experimental group (EG), which participated in the videoconferencing sessions, and 21 to the control group. Three questionnaires were administered: WHO-DAS II, Sickness Impact Profile, and SF-36 Health Survey. Effectiveness was assessed by a pre-post design. An online psychosocial program was applied over three-month period. Data revealed an improvement of the EG in psychosocial variables, e.g. "Getting along with people" (z = -2.289, r = -.47, p ≤ .05) or "Psychosocial Domain" (z = -2.404, r = -.49, p ≤ .05), and in physical variables, e.g. "Life activities" (z = -2.844, r = -.58, p ≤ .05). Social interaction appeared as a relevant factor at improving HRQoL levels. High levels of satisfaction about the teleassistance program were reported.