A case of adult-onset Krabbe disease diagnosed by <i>galactocerebrosidase</i> gene mutations, presenting with an atypical phenotype

Adult-onset Krabbe disease is a rare neurodegenerative disorder caused by mutations in the galactocerebrosidase (GALC) gene. It typically presents with slowly progressive central nervous system involvement, primarily characterized by pyramidal tract signs. We report the case of a 74-year-old man who presented with slowly progressive, asymmetric muscle atrophy associated with peripheral neuropathy, but without any clinical evidence of pyramidal tract involvement. Neurological examination revealed muscle wasting and weakness without spasticity or pathological reflexes. Based on the clinical presentation, differential diagnoses included motor neuron disease, Charcot-Marie-Tooth disease, and chronic inflammatory demyelinating polyneuropathy. Genetic analysis revealed a known pathogenic missense variant in the GALC gene: c.246A>G (p.I82M), confirming the diagnosis of Krabbe disease. These mutations have been previously reported in adult-onset Krabbe disease. This case lacked typical central nervous system signs and represents an atypical phenotype that may lead to delayed diagnosis. Our findings suggest that Krabbe disease should be considered in the differential diagnosis of adult patients presenting with unexplained neuropathy and marked muscle atrophy. Genetic testing plays a critical role in identifying such atypical cases, particularly when conventional diagnostic approaches fail to provide a definitive diagnosis.