Objective: ​​​​​​Childhood-onset Huntington’s disease (HD) is a rare subset of HD with symptom-onset before the age of 18 years. We here detail the presenting movement disorder spectrum in seven cases of childhood-onset HD, evaluated between 2022-2024.

Background: HD in adulthood typically manifests with generalized and progressive chorea. In contrast, childhood-onset HD, which represents 3-10% of all cases, typically does not manifest chorea initially but rather presents with cognitive decline, behavioral dysregulation, epilepsy and a diverse spectrum of movement disorders. This presents distinct challenges in diagnosis and management.

Method: A combination of detailed clinical assessments, standardized video recording, HTT repeat expansion testing, and review of brain MRI findings.

Results: Where parental testing was possible, all cases had a positive family history of genetically confirmed HD. Within our cohort of 7 patients, all had early cognitive or behavioral symptoms preceding motor symptoms. The most common amongst these included cognitive decline, ADHD, ASD, aggression, sleep disorder, and anxiety. The movement disorder spectrum upon initial presentation included dystonia, myoclonus, Parkinsonism, and chorea. Notably, all patients presented with severe and progressive dysarthria. Although a negative correlation (r = -0.56) between length of CAG repeats and age at motor symptom onset was noted, it did not reach statistical significance. Of the 6 available imaging studies, all showed significant volume loss of the caudate and putamen.

Conclusion: Our findings underscore the importance of recognizing neurodevelopmental symptoms as an early manifestation of childhood-onset HD. The spectrum of presenting movement disorders is broad and evolves throughout the disease course. Dedicated testing for HD should be considered in children presenting with neurodevelopmental concerns and movement disorders, particularly in the setting of a positive family history or unavailability of parental testing. Given the heterogeneity of presenting symptoms, a multidisciplinary approach should be taken with the management of these patients, including early involvement of OT, PT, SLP, and specialties such as psychiatry, neurology, genetics, and palliative care.

Brain MRIs of patient cohort

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-spectrum-of-presenting-phenotypes-in-childhood-onset-huntingtons-disease/