Why the study?
NEB-related myopathy typically presents with symmetric, proximal-dominant muscle weakness, and reports of nemaline myopathy with distal-dominant muscle involvement are rare.
This case expands the known genotype-phenotype correlation of pathogenic NEB variants by reporting a rare presentation of asymmetric, distal-dominant muscle weakness.
Atypical distal asymmetric NEB myopathy broadens diagnostic consideration; leaves open variant causality and phenotypic spectrum.
We report the case of a 37-year-old female who presented with asymmetric, distal muscle weakness in the lower limbs, which had its onset in childhood. Muscle biopsy revealed pathological changes consistent with nemaline myopathy, and suspected biallelic variants in the nebulin (NEB) gene, NM_001271208.1:c.24684G>C p.(Ser8228Ser) and c.23847+164A>G were identified. NEB-related myopathy typically presents with symmetric, proximal-dominant muscle weakness and atrophy. However, reports of nemaline myopathy with distal-dominant muscle involvement are rare. This case exhibited a marked asymmetric, distal-dominant myopathy in the early stages of the disease, and it may contribute to our understanding of the genotype-phenotype correlation of pathogenic NEB variants.
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Mizutani et al. (2025) studied this question.
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