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.

Restless legs syndrome in Parkinson's disease.

The present study explores the frequency of RLS in PD and focuses on the clinical differences between patients with and without restless legs syndrome (RLS). A cross-sectional study was designed, comprising 114 patients diagnosed with PD. Those patients positive for RLS were assessed for intensity of the syndrome (IRLS). We compared the clinical characteristics of the patients with and without RLS, using specific scales: Unified Parkinson's Disease Rating Scale (UPDRS I-IV), quality of life (Parkinson's Disease Questionnaire, PDQ 39), sleep symptoms (Parkinson's Disease Sleep Scale, PDSS), and diurnal hypersomnia (Epworth Sleepiness Scale). Twenty-five patients (21.9%) out of a total of 114 subjects diagnosed with PD met the RLS diagnostic criteria. RLS was more frequent in women (68%). The patients with RLS showed poorer scores on the PDSS (PD-RLS+: 102.4 +/- 15.1 vs PD-RLS-: 113.2 +/- 16.4) (P = 0.005) and in the bodily discomfort dimension of the PDQ-39 (PD-RLS+ 6.1 +/- 3.4 vs PD-RLS- 3.8 +/- 2.6) (P = 0.002). Analysis of the subscales of the PDSS showed significant differences (P < 0.001) between both groups of patients in items 4 and 10, and to a lesser degree in items 5 (P = 0.01) and 11 (P = 0.02) There was no increased incidence of diurnal hypersomnia in the group of patients with RLS. There were no differences in the rest of the variables. RLS is frequent in patients with PD, though this condition doesn't apparently affect quality of life or lead to an increased presence of diurnal hypersomnia. It would be advisable to validate the diagnostic criteria of RLS in this specific group of patients.