A recurrent de novo DYNC1H1 tail domain mutation causes spinal muscular atrophy with lower extremity predominance, learning difficulties and mild brain abnormality.

•De novo missense mutation c.751C>T in DYNC1H1 gene is a pathogenic mutation causing SMALED.•The mutation has a high phenotypic-genotypic correlation in 4 unrelated patients.•Leg muscle MRI findings are highly specific in DYNC1H1-related SMALED.•Muscle biopsy findings are variable and non-specific so has limited use in DYNC1H1-related SMALED.