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Question Date: 20/07/2023

Question: 10 year old boy was referred by a pediatrician with a diagnosis of dystonic cerebral palsy He was born of a non consanguineous marriage with normal developmental milestones, he had walking difficulty from 5 years of age. He had abnormal lower limb posturing, and neck posturing. On enquiry he said that his symptoms are worse in the evening ,as he is engaged in activities, improves markedly after sleep, on walking up in the morning Examination revealed generalized dystonia, worse on walking. No KF ring Which enzyme deficiency is not responsible for this disorder?

Options:

Dopamine beta hydroxylase
GTP cyclohydrolase 1
Tyrosine hydroxylase
sepiapterin reductase

Correct Answer: Dopamine beta hydroxylase

Explaination: Dopa-responsive dystonia (DRD) encompasses a group of clinically and genetically heterogeneous disorders that typically manifest as limb-onset, diurnally fluctuating dystonia and exhibit a robust and sustained response to levodopa treatment Autosomal dominant GTP cyclohydrolase 1 deficiency, also known as Segawa disease, is the most common and best-characterized condition that manifests as DRD, but a similar presentation can be seen with genetic abnormalities that lead to deficiencies in tyrosine hydroxylase, sepiapterin reductase or other enzymes that are involved in the biosynthesis of dopamine.

Reference: Wijemanne, S. & Jankovic, J. Dopa-responsive dystonia--clinical and genetic heterogeneity. Nat Rev Neurol 11, 414?424 (2015).