Case Report: Nemaline myopathy in an infant with hypotonia

Abstract

Introduction: Nemaline myopathies (NM) are a group of congenital myopathies characterized by early-onset muscle weakness and hypotonia. They result from mutations in genes encoding structural or regulatory proteins of the thin filament, with NEB and ACTA1 being the most frequently affected. The availability of next-generation sequencing has facilitated the identification of causal variants, enabling genotype-phenotype correlations and guiding clinical management.

Case Report: We present a three-month-old female infant, with no relevant prenatal history, who since birth exhibited weak crying, poor sucking and swallowing, with episodes of regurgitation and bronchoaspiration. Physical examination revealed generalized hypotonia, reduced spontaneous movements, absent deep tendon reflexes, and mild craniofacial dysmorphism. Brain CT showed corpus callosum hypoplasia, while metabolic studies and muscle enzyme levels were normal. Genetic testing identified two pathogenic variants in the NEB gene (c.1493A>G and c.17828del), confirming the diagnosis of autosomal recessive nemaline myopathy. The patient required supportive interventions, including Nissen fundoplication, gastrostomy, and tracheostomy due to respiratory failure, along with physical and respiratory therapy and pharmacological management with L-tyrosine. She is currently being prepared for home mechanical ventilation.

Conclusions: Hypotonia in infants represents a diagnostic and therapeutic challenge, particularly in resource-limited settings. Access to genetic testing is crucial to confirm etiology, guide multidisciplinary management, and provide families with a more accurate prognosis. The identification of specific gene mutations associated with NM opens the door to potential targeted therapies, aiming to improve quality of life and survival in affected patients.