Childhood-onset Huntignton´s disease. A rare presentation.

Introduction: Huntington's disease (HD) is a rare autosomal dominant disease caused by the expansion of CAG triplets in the gene that encodes huntingtin. There are earlier symptoms' onset in offspring due to the phenomenon of anticipation. The clinical features of childhood-onset HD, before age 10 years, differs from adult-onset form. It is characterized by motor impairment, behavioral difficulties and delay or regression in areas of development; while chorea is rarely seen. In this case we describe clinical aspects of a patient with childhood-onset Huntington's disease.

Case report: A 5-year-old girl with a family history of HD and typical development up to 3 years of age. She progressively acquired language impairment with skills that were below her age in expressive and receptive areas, without deficits in pragmatic and social skills. Regarding motor skills, she manifested instability at walking and standing, with rigidity, dystonia and choreic movements. Atrophy of the basal ganglia was evident on MRI, EEG was normal, and molecular confirmation of CAG triplet revealed repeat length of 51 copies.

Conclusion: Childhood-onset HD differs from adult-form´s clinical manifestations. It should be considered in patients with progressive motor and cognitive impairment. Due to family inheritance, it is important to carefully examine family history and take it into account even without relatives affected, considering the anticipation phenomenon.