Objective: To describe a unique case of a woman who presented as a progressive cerebellar ataxia, with no family history of neurological diseases, that after extensive investigation was diagnosed as Huntington’s Disease (HD).

Background: Motor symptoms in HD are typically related to chorea and occasionally parkinsonism, myoclonus, and dystonia. Non-choreiform movements, such as ataxia, are rarely seen at the presentation of patients with HD.

Method: Report of a case evaluated at ataxia’s ambulatory in neurology department of Federal University of Parana, in Curitiba, Brazil.

Results: A 42-year-old previously healthy woman presented with a one-year history of progressive gait imbalance followed by personality changes including excessive irritability and anxiety. Family history was negative for any neurological condition. Examination revealed gait ataxia, slow saccades with increased latency, mild dysmetria, dysarthria, bradykinesia, and mild cognitive impairment (MMSE of 23/30). No involuntary movements were observed. Further work up included blood tests (vitamin E, alpha-fetoprotein, albumin) and MRI brain; the former were negative while the latter showed diffuse atrophy. The diagnosis at that time remained unclear; the patient was treated conservatively. Two years thereafter, she developed appendicular choreiform and dystonic movements. Brain imaging was repeated, which then showed diffuse atrophy as well as atrophy of the caudate nuclei. Genetic testing revealed in the patient 19/45 CAG repeats in the HTT gene, which was consistent with HD. Parental testing revealed 15/17 expansions in the mother, and 14/29 expansions in the father, showing an allele in the intermediary range of mutation.

Conclusion: The case described above has at least two important peculiarities – (i) the atypical presentation, which comprised of cerebellar ataxia two years prior to the development of involuntary movements, (ii) the negative family history. Clinicians should be familiar with the possibility of patients with HD presenting with ataxia, without any initial association with chorea, and with no family history of movements disorders. This knowledge is of paramount importance because it may prevent misdiagnosis of sporadic ataxia in early stages of HD.

References: 1. American college of medical genetics/american society of human genetics/huntington disease genetic testing working group (acmg/ashg statement). Laboratory guidelines for Huntington disease genetic testing. Am J Hum Genet, v. 62, p. 1243-1247, 1998. 2. Hayden MR. Huntington’s Chorea. New York: Springer- Verlag, 1981 
 3. Squitieri F, Berardelli A, Nargi E, Castellotti B, Mariotti C, Cannella M, Lavitrano ML, de Grazia U, Gellera C, Ruggieri S. Atypical movement disorders in the early stages of Huntington’s disease: clinical and genetic analysis. Clin Genet. 2000 Jul;58(1):50-56 4. Dong Y, Sun Y-M, Liu Z-J, Ni W, Shi S-S, Wu Z-Y. Chinese patients with Huntington’s disease initially presenting with spinocerebellar ataxia. Clin Genet 2012 5. Almqvist E.W., Elterman D.S., MacLeod P.M., Hayden M.R. High incidence rate and absent family histories in one quarter of patients newly diagnosed with Huntington disease in British Columbia. Clin. Genet. 2001;60:198–205.

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