Analyzing the type and frequency of patient‐specific mutations that give rise to Duchenne muscular dystrophy (DMD) is an invaluable tool for diagnostics, basic scientific research, trial planning, and improved clinical care. Locus‐specific databases allow for the collection, organization, storage, and analysis of genetic variants of disease. Here, we describe the development and analysis of the TREAT‐NMD DMD Global database (http://umd.be/TREAT_DMD/). We analyzed genetic data for 7,149 DMD mutations held within the database. A total of 5,682 large mutations were observed (80% of total mutations), of which 4,894 (86%) were deletions (1 exon or larger) and 784 (14%) were duplications (1 exon or larger). There were 1,445 small mutations (smaller than 1 exon, 20% of all mutations), of which 358 (25%) were small deletions and 132 (9%) small insertions and 199 (14%) affected the splice sites. Point mutations totalled 756 (52% of small mutations) with 726 (50%) nonsense mutations and 30 (2%) missense mutations. Finally, 22 (0.3%) mid‐intronic mutations were observed. In addition, mutations were identified within the database that would potentially benefit from novel genetic therapies for DMD including stop codon read‐through therapies (10% of total mutations) and exon skipping therapy (80% of deletions and 55% of total mutations).

Skeletal muscle damaged by injury or by degenerative diseases such as muscular dystrophy is able to regenerate new muscle fibers. Regeneration mainly depends upon satellite cells, myogenic progenitors localized between the basal lamina and the muscle fiber membrane. However, other cell types outside the basal lamina, such as pericytes, also have myogenic potency. Here, we discuss the main properties of satellite cells and other myogenic progenitors as well as recent efforts to obtain myogenic cells from pluripotent stem cells for patient-tailored cell therapy. Clinical trials utilizing these cells to treat muscular dystrophies, heart failure, and stress urinary incontinence are also briefly outlined.

Objective: To describe the frequency of antibodies against neurofascin in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and the associated clinical features. Methods: Immunocytochemistry was used to identify antibodies to neurofascin 155 (NF155) and 186. Serum reactivity with paranodes and brain tissue was tested with immunohistochemistry of teased-nerve fibers and rat brain. Antibody titers and immunoglobulin (Ig) G isotypes were determined using ELISA. Clinical information was obtained retrospectively. Results: Two of 53 patients, but none of 204 controls, had antibodies to NF155 (p = 0.041). The 2 patients with NF155 antibodies developed severe polyradiculoneuropathy with predominant distal weakness that was refractory to IVIg. Eight additional patients with IVIg-refractory CIDP were then identified from a national database; 2 of them with the same clinical features also had NF155 antibodies. Overall, 3 of the 4 patients with NF155 antibodies had a disabling and characteristic tremor (high amplitude, low frequency, postural, and intention). Patients9 antibodies reacted with the paranodes in teased-nerve fibers and with the neuropil of rat cerebellum, brain, and brainstem. Anti-NF155 antibodies were predominantly of the IgG4 isotype in all patients. Conclusion: Patients with CIDP positive for IgG4 NF155 antibodies constitute a specific subgroup with a severe phenotype, poor response to IVIg, and disabling tremor. Autoantibodies against paranodal structures associate with distinct clinical features in CIDP and their identification has diagnostic, prognostic, and therapeutic implications. Classification of evidence: This study provides Class IV evidence that autoantibodies to NF155 identify a CIDP subtype characterized by severe neuropathy, poor response to IVIg, and disabling tremor.

Objective: Rituximab has emerged as an efficacious option for drug-resistant myasthenia gravis (MG). However, reports published only describe the short-term follow-up of patients treated and little is known about their long-term clinical and immunologic evolution. Our objective was to report the clinical and immunologic long-term follow-up of 17 patients (6 MuSK+MG and 11 AChR+MG) and compare the response between AChR+MG and MuSK+MG patients. Methods: Myasthenia Gravis Foundation America postintervention status and changes in treatment and antibody titers were periodically determined. Lymphocyte subpopulations, total immunoglobulin, immunoglobulin G (IgG) anti-MuSK subclasses, and anti-tetanus toxoid IgG before and after treatment were also studied. Results: After a mean post-treatment period of 31 months, 10 of the AChR+MG patients improved but 6 of them needed reinfusions. In contrast, all MuSK+MG patients achieved a remission (4/6) or minimal manifestations (2/6) status and no reinfusions were needed. Consequently, in the MuSK+MG group, prednisone doses were significantly reduced and concomitant immunosuppressants could be withdrawn. Clinical improvement was associated with a significant decrease in the antibody titers only in the 6 MuSK+MG patients. At last follow-up MuSK antibodies were negative in 3 of these patients and showed a decrease of over 80% in the other 3. Conclusion: In view of the long-lasting benefit observed in MuSK+MG patients, we recommend to use rituximab as an early therapeutic option in this group of patients with MG if they do not respond to prednisone. Classification of evidence: This study provides Class IV evidence that IV rituximab improves the clinical and immunologic status of patients with MuSK+MG.

Objective: To describe the response to rituximab in patients with treatment-resistant chronic inflammatory demyelinating polyneuropathy (CIDP) with antibodies against paranodal proteins and correlate the response with autoantibody titers. Methods: Patients with CIDP and IgG4 anti–contactin-1 (CNTN1) or anti–neurofascin-155 (NF155) antibodies who were resistant to IV immunoglobulin and corticosteroids were treated with rituximab and followed prospectively. Immunocytochemistry was used to detect anti-CNTN1 and anti-NF155 antibodies and ELISA with human recombinant CNTN1 and NF155 proteins was used to determine antibody titers. Results: Two patients had a marked improvement; another patient improved slightly after 10 years of stable, severe disease; and the fourth patient had an ischemic stroke unrelated to treatment and was lost to follow-up. Autoantibodies decreased in all patients after rituximab treatment. Conclusions: Rituximab treatment is an option for patients with CIDP with IgG4 anti-CNTN1/NF155 antibodies who are resistant to conventional therapies. Classification of evidence: This study provides Class IV evidence that rituximab is effective for patients with treatment-resistant CIDP with IgG4 anti-CNTN1 or anti-NF155 antibodies.