Limb-girdle muscular dystrophies (LGMD) are a group of genetically heterogeneous disorders characterized by predominantly proximal muscle weakness.
The Brazilian clinicians aimed to characterize epidemiological, clinical and molecular data of patients with autosomal recessive LGMD2/LGMD-R in Brazil.
A multicenter historical cohort study was performed at 13 centers, in which index cases and their affected relatives’ data from consecutive families with genetic or pathological diagnosis of LGMD2/LGMD-R were reviewed from July 2017 to August 2018. Survival curves to major handicap for LGMD2A/LGMD-R1-calpain3-related, LGMD2B/LGMD-R2-dysferlin-related and sarcoglycanopathies were built and progressions according to sex and genotype were estimated.
In 370 patients (305 families) with LGMD2/LGMD-R, most frequent subtypes were LGMD2A/LGMD-R1-calpain3-related and LGMD2B/LGMD-R2-dysferlin-related, each representing around 30% of families. Sarcoglycanopathies were the most frequent childhood-onset subtype, representing 21% of families. Five percent of families had LGMD2G/LGMD-R7-telethonin-related, an ultra-rare subtype worldwide. Females with LGMD2B/LGMD-R2-dysferlin-related had less severe progression to handicap than males and LGMD2A/LGMD-R1-calpain3-related patients with truncating variants had earlier disease onset and more severe progression to handicap than patients without truncating variants.
The authors have provided paramount epidemiological data of LGMD2/LGMD-R in Brazil that might help on differential diagnosis, better patient care and guiding future collaborative clinical trials and natural history studies in the field.
Clinicogenetic lessons from 370 patients with autosomal recessive limb-girdle muscular dystrophy. Winckler PB, da Silva AMS, Coimbra-Neto AR, Carvalho E, Cavalcanti EBU, Sobreira CFR, Marrone CD, Machado-Costa MC, Carvalho AAS, Feio RHF, Rodrigues CL, Gonçalves MVM, Tenório RB, Mendonça RH, Cotta A, Paim JFO, Costa E Silva C, de Aquino Cruz C, Bená MI, Betancur DFA, El Husny AS, de Souza ICN, Duarte RCB, Reed UC, Chaves MLF, Zanoteli E, França MC Jr, Saute JA. Clin Genet. 2019 (Oct).