Clinical and Molecular Features of Myotonic Dystrophy Type 1 in Peru (P5.066)

Objective: To describe the clinical and molecular characteristics of DM1 patients followed at a tertiary care center in Peru. Background: Myotonic Dystrophy Type 1 is a multisystemic and pleiotropic neuromuscular disorder caused by an abnormal CTG expansion at the DMPK gene. Outside of Mexico, Brazil and Costa Rica, only a few DM1 cases with accompanying confirmatory diagnosis have been reported in Latin America, likely due to limited access to the molecular diagnosis. Methods: Clinical data was obtained from 72 cases with a clinical diagnosis of DM1 followed from 2009 to 2014 at the Neurogenetics Research Center of the Instituto Nacional de Ciencias Neurologicas in Lima, Peru. Molecular analysis based on PCR and TP-PCR was performed for all cases and 17 of the cases were also confirmed by capillary electrophoresis through the Rede Neurogenetica in Brazil. Results: We confirmed an abnormal CTG expansion within the DMPK gene in 66 out of 72 subjects (91.7[percnt]). Normal alleles ranged from 5 to 29 CTG repeats. In most of the cases, the origin was traced back to either Lima (34.72.5[percnt]) or Southern Peru (30.56[percnt]). The mean age at onset of the disease was 25.8 ±13.4 [3-59]. 64.4[percnt] cases had a positive family history. The main clinical signs observed were weakness (96.88[percnt]), myotonia (96.92[percnt]) and cataracts (31.15[percnt]). Cardiologic manifestations included: AV block (36.96[percnt]), branch block (82.6[percnt]), and cardiomyopathy (33.33[percnt]). Diabetes (7.27[percnt]), hypothyroidism (23.52[percnt]), and hypotestosteronism (50[percnt]) were the main associated endocrine disorders. Conclusions: This is the first DM1 study in a Peruvian population. DM1 cases involved both muscular and systemic manifestations that require a multidisciplinary health care approach. Although the DM1 phenotype is well characterized, molecular diagnosis is necessary to rule out phenocopies and to provide appropriate genetic counseling. Disclosure: Dr. Milla-Neyra has nothing to disclose. Dr. Inca-Martinez has nothing to disclose. Dr. Ortega-Davila has nothing to disclose. Dr. Marca has nothing to disclose. Dr. Tirado-Hurtado has nothing to disclose. Dr. Cabrejo-Bravo has nothing to disclose. Dr. Lindo-Samanamud has nothing to disclose. Dr. Saraiva-Pereira has nothing to disclose. Dr. Mazzetti has received personal compensation for activities with commercial entities. Dr. Jardim has nothing to disclose. Dr. Cornejo Olivas has nothing to disclose.