We report a novel de-novo mutation in the Dynein, cytoplasmic1, heavy chain1 (DYNC1H1) gene presenting with the clinical phenotype of sporadic congenital SMA-LED, lower limb contractures, perisylvian polymicrogyria and epileptic encephalopathy. We report a male infant born to non-consanguineous parents, with fetal akinesia and oligohydramnios detected at 20 weeks gestation. At birth, arthrogryposis was evident with bilateral hip dislocation. Dysmorphic features: shallow orbits, high-arched palate, posteriorly rotated ears, spatulate digits and ulnar drift raised suspicion of a connective tissue disorder. The onset of seizures, with irritability and developmental stasis at seven months, prompted involvement of paediatric neurology. Examination indicated paucity of lower limb movement and absent lower limb reflexes. Upper limb strength and reflexes were preserved. MRI brain demonstrated bilateral perisylvian polymicrogyria. Serial EEGs captured myoclonic and atonic seizures, with electrodecrement and evolution of an epileptic encephalopathy. Nerve Conduction Studies and Electromyography demonstrated generalised motor neuronopathy. Next Generation Sequencing revealed a de-novo heterozygous missense variant in exon 20 of the DYNC1H1 gene: c.4259T>G, p.(Leul420Arg). In silico analysis predicts a deleterious effect on protein function. To our knowledge, this is the only DYNC1H1 mutation reported within the stem domain of the protein and postulate that this has contributed to the severity of both central and peripheral manifestations of SMA-LED in this case. Pathogenic variants in the DYNC1H1 gene have previously been described with SMA-LED with and without polymicrogyria. This case broadens the phenotype of DYNC1H1 to include an epileptic encephalopathy, with onset of epilepsy in infancy, emphasising the relevance of dyneins in axonal pathology within the peripheral and central nervous systems.