An Unusual Case of TH Mutation Presenting with Titubation: Movement Disorder

Introduction: Tyrosine hydroxylase (TH) is a key enzyme in catecholamine biosynthesis, playing a crucial role in dopamine (DOPA) production.Tyrosine hydroxylase deficiency has a broad clinical spectrum ranging from DOPA-responsive dystonia to severe infantile encephalopathy.Although classically presenting with hypokinesia, rigidity, and dystonia, atypical phenotypes can mimic other neurological disorders, often leading to misdiagnosis and delayed treatment.Case description: In a family of four, the patient's elder sister having an uneventful birth, had global developmental delay and presented as a cerebral palsy (CP) mimic, initial investigations and magnetic resonance imaging (MRI) Brain were normal, on suspicion of genetic abnormality, whole exome sequencing was done showing homozygous mutation in TH gene and DOPA trial was started, following which there is marked improvement.The patient, a 6-month-old male, had an uneventful birth, was neurodevelopmentally normal till 5 months of age, when parents noticed head titubation.Neurological examination revealed rhythmic oscillatory movements without signs of spasticity, dystonia, or developmental regression.more in the morning and increased crying, these movements also improved with a low dose of DOPA.Discussion: This case highlights an unusual presentation of TH deficiency with isolated titubation as an early sign.It underscores the expanding phenotypic variability of the disorder and the potential for misdiagnosis, particularly when the presentation deviates from classical motor findings.Early recognition and treatment with DOPA replacement can result in significant clinical recovery.Moreover, the presence of a similarly affected sibling earlier diagnosed as CP mimics emphasizes the need for heightened clinical suspicion and appropriate workup in familial cases of unexplained movement disorders.