This case report documents an unusual presentation of dopa-responsive dystonia (DRD) in three siblings (two females, one male) which simulated cerebral palsy (CP) and describes the evolution of their spinal deformity in relation to growth and responsiveness to levodopa therapy. The siblings were normal at birth with a negative history of neurological disease or spinal imbalance. They showed marked phenotypic variation but all developed progressive scoliosis and neurological impairment with mixed spastic dystonic features, leading to the misdiagnosis of spastic dystonic CP. Age at establishment of the diagnosis of DRD and levodopa trial for the three patients was 12 years, 9 years 6 months, and 3 years 6 months respectively. In patients 1 and 3, spinal deformity responded dramatically to levodopa treatment and neurological symptoms were ameliorated. Patient 2 developed a rigid scoliotic curve and, despite neurological improvement with levodopa, the spinal curvature remained unresponsive necessitating surgical correction. Spinal decompensation is a common manifestation of DRD, which with early diagnosis and initiation of levodopa treatment has an excellent prognosis. This report highlights the variability of clinical expression in DRD and the importance of an adequate trial of levodopa when unexplained dystonic features are documented.