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Background: LAMA2-related dystrophies (LAMA2-RD) are a rare group of neuromuscular disorders with a broad spectrum of phenotype severity, ranging from mild to severe. We performed a cross-sectional study of LAMA2-RD through motor function and pulmonary tests to establish the disease's natural history., Methods: Forty-four individuals with LAMA2-RD were included and evaluated once through functional outcome measures including Motor Function Measure 32 (MFM32), Revised Upper Limb Module (RULM), goniometry, and Forced Vital Capacity (FVC). Fixed Effect Regression Model (ERM) and Kaplan-Meier curve were used for calculating the rate of the disease progression RESULTS: Patients were between 2 and 25 years old (mean 11.4), the most frequent phenotype presentation was non-ambulant (N=36, 81.8%) while eight patients (18,2 %) were ambulant. The non-ambulant group presented a more severe progression of the disease. Non-ambulant patients had a 1.85 % decrease in FVC/year against 1.32 %/year among ambulant patients. In the non-ambulant group, there was a 4.2 % drop/year in the MFM32-D2 domain (p<0.00001), a 2.6 % drop/year in the D3 domain (p<0.0001), and a 2.7 % drop/year in the MFM32 global assessment (p<0.0001). However, the non-ambulant group's evaluation of upper limb function through the RULM scale did not show a statistically significant reduction. In the non-ambulant group, elbow and knee retractions worsened 3.22 degrees/year (p=0.00087) and 1.92 degrees/year, respectively. While in those patients who acquired gait, elbow and knee retractions worsened 2.45 degrees/year (p=0.0003) and 1.73 degrees/year (p=0.01), respectively., Conclusion: This study confirmed the progressive nature of LAMA2-RD, both in ambulant and non-ambulant patients. MFM32, FVC, and goniometry were identified as promising outcome measures for natural history studies and clinical trials in LAMA2-RD., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objectives: Collagen VI-related dystrophies (COL6-RDs) have a broad clinical spectrum and are caused by mutations in the COL6A1, COL6A2 and COL6A3 genes. Despite the clinical variability, two phenotypes are classically recognized: Bethlem myopathy (BM, milder form) and Ullrich congenital muscular dystrophy (UCMD, more severe form), with many patients presenting an intermediate phenotype. In this work, we present clinical and genetic data from 28 patients (27 families), aged 6-38 years (mean of 16.96 years), with COL6-RDs., Patients and Methods: Clinical, muscle histology and genetic data are presented. COL6A1, COL6A2 and COL6A3 genes were analyzed by next-generation sequencing (NGS)., Results: Homozygous or heterozygous variants were found in COL6A1 (12 families), COL6A2 (12 families) and COL6A3 (3 families). Patients with the severe UCMD phenotype (three cases) had a homogeneous clinical picture characterized by neonatal onset of manifestations, no gait acquisition and a stable course, but with severe respiratory involvement. Most of the patients with the mild UCMD phenotype had neonatal onset of manifestations (88.8 %), delayed motor development (66.6 %), slowly progressive course, pulmonary involvement (55.5 %) and loss of the walking capacity before the age of 10 (66.6 %). In the intermediate group (nine patients), some children had neonatal onset of manifestations (44.5 %) and delayed motor development (88.9 %); but all of them achieved the ability to walk and were still ambulatory. Some patients that had the BM phenotype presented neonatal manifestations (57.1 %); however, all of them had normal motor development and normal pulmonary function. Only one patient from the group of BM lost the walking capacity during the evolution of the disease. Other frequent findings observed in all groups were joint retractions, spinal deformities, distal hyperextensibility, congenital hip dislocation and keloid formation., Conclusion: COL6-RDs present variable clinical manifestations, but common findings are helpful for the clinical suspicion. NGS is a valuable approach for diagnosis, providing useful information for the genetic counseling of families., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)