Miotonía congénita de Becker, un reto diagnóstico. Caso clínico

Abstract

Becker's type myotonia congenita, an autosomal recessive non-dystrophic disorder belonging to chloride channelopathies, is caused by mutations in the CLCN1 gene. It is characterized by delayed relaxation of muscle fibers as opposed voluntary muscle contraction. The general objective of this study was to describe a clinical case of Becker's type myotonia congenita for a subsequent analysis and bibliographic search. The clinical case was that of a 10-years-old male with Becker's type myotonia congenital. Data collection was carried out conducting interview with the patient and his parents, physical examination and pre-existing studies. Discussion was based on supplementary bibliography selected by PRISMA, using PUBMED, SCIELO and SCIENCE DIRECT databases. The most relevant results of the case indicated that the characteristic symptom was the myotonic phenomenon in lower extremities which improved with repetitive movements. Creatine kinase remained at basal values, EMG myotonic discharges were found, and genetic sequencing confirmed variant c.180+3A>T p.? of the CLCN1 gene. The patient was treated with carbamazepine, reporting a favorable evolution. Accurate and early diagnosis is essential in this type of rare diseases that affect the quality of life, EMG and genetic tests are effective to diagnoses Becker's myotonia congenita.