We describe an 8-year-old boy with history of developmental regression at 3 months, and further regression with illness. He had irregular distal hand postural and kinetic tremor, mostly but also some proximal component, stiff-legged gait with equinovarus posturing, and painful toe flexion dystonia. Trio-WES revealed a de-novo variant in DNM1L. He was treated with carbidopa/levodopa with significant improvement in dystonia, tremor, balance and gait.  

We describe a 12-year-old girl with history of developmental delay noted at 9 months of age, developmental regression with loss of ability to walk around 2 years of age due to weakness, action tremor, strabismus, rigidity, and chorea. MRI brain showed asymmetric, irregular round areas of T1 hyperintensity in the bilateral thalami. Muscle biopsy was consistent with metabolic myopathy. Trio-WES revealed a novel, de novo pathogenic variant and one variant of unknown significance in DNM1L.  She was treated with carbidopa/levodopa resulting in improved gait and ability to ambulate with a walker.