Instituto Mayor Campesino

Abstract Usher syndrome (USH) is the most common genetic condition responsible for combined hearing and vision loss. This report presents the first case of USH type 2C (USH2C) in Colombia. The patient was a 5-year-old girl with moderate-to-severe sensorineural hearing loss and delayed language development. No signs of ataxia, balance disorders, or visual impairments were evident during the physical examination. Whole exome sequencing revealed a homozygous pathogenic variant in the ADGRV1 gene, confirming the diagnosis of USH2C. Genetic counseling was provided, and the patient was fitted with hearing aids with advanced sound processing technology, which resulted in significant benefit and the achievement of appropriate language development milestones. The patient is currently enrolled in school. USH should be considered as part of the differential diagnosis, even in patients with hearing loss in the absence of visual disturbances. Early and accurate diagnosis of USH is essential for proper clinical management.

We presented in \cite{bl2,bl7} an approach to derive the metastable behavior of continuous-time Markov chains. We assumed in these articles that the Markov chains visit points in the time scale in which it jumps among the metastable sets. We replace this condition here by assumtpions on the mixing times and on the relaxation times of the chains reflected at the boundary of the metastable sets.