Objective: To describe the prevalence, clinical and molecular characteristics of a series of LOHD patients in an Argentinean cohort.

Background: Late onset Huntington’s disease (LOHD) represents 4.4-11.5% of the HD population, presenting mild motor signs, slow progression, lower neuropsychiatric and cognitive impairment and age at onset ≥ 60 years. LOHD information in Argentina is scarce.

Methods: We conducted an observational study based on 2 institution’s registry review of a total of 94 individuals with clinical and molecular diagnosis of HD.

Results: Nine LOHD patients (6 men and 3 women), average age 75 ± 4.63 years (range 65-84 years), from 9 different families, forming 9,57% of the analyzed population. The initial symptoms were motor in all cases, inheritance was paternal in 3 cases, and in other 3 it could not be established. Interestingly, in 4 cases the CAG length was in the reduced penetrance range (36 – 39). The mean number of repetitions for the expanded allele was 40 (range 38 – 44), and 19,5 (range 16 -24) for the not expanded.

Conclusions: This population shows a frequency of LOHD similar to that reported in the literature. Phenotype expression was predominantly motor with a low number of CAG repetitions, including expanded allele on the reduced penetrance range. This observation is relevant, as it has been estimated that patients with 36-39 CAG repeats have a 40% chance to be asymptomatic at age 65 years and a 30% chance at age 75 years. Late onset HD represent a diagnostic and genetic challenge due to its slow progression, unawareness of manifestations among patients and in many cases, mild symptomatology that doesn’t lead to search for meal attention.

References: Adult-onset Huntington’s Disease that presented without chorea – Atsushi Iwata, Kenji Ishihara and Shoji Tsuji (2013). What do we know about late onset Huntington’s Disease? Sai S. Chagantia,b, Elizabeth A. McCuskera,b and Clement T. Loy (2017).

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MDS Abstracts - https://www.mdsabstracts.org/abstract/late-onset-huntingtons-disease-in-an-argentinian-cohort/