Objective: To characterize an Iranian Huntington’s disease (HD) cohort and quantify associations between CAG repeat length, age at onset, motor severity, and caregiver burden.

Background: Population-specific HD data from the Middle East are limited [1], yet such data are needed to contextualize phenotypic variability and support caregiver-focused care planning [2].

Method: This cohort included individuals with a clinical diagnosis of HD confirmed by a genetic test (n=113), collected between February 2024 and February 2026. Demographics and total scores from the MDS-UHDRS motor assessment and Zarit Burden Interview-12 (ZBI-12) were summarized using variable-specific available-case denominators. Pearson and Spearman correlation were used for continuous and ordinal variables with pairwise complete cases, respectively. Statistically significant associations were examined with linear regression. Scatter plots with fitted curves were generated for visualization.

Results: Participants were 56% female; mean age was 49±12 years. Among those with available data, mean age at onset was 44±11 (n=62), disease duration 7±7 years (n=62) [figure1][Table1], and mean CAG repeat length 43±4 (n=44) [figure2][Table2]. Categorical variables are described in [Table3]. Mean total motor score was 50±31 (n=96) and mean ZBI-12 total score 23±11 (n=37). CAG repeat length correlated inversely with age at onset (r=-0.59; p=0.002) [Table 4]. In regression, each additional CAG repeat was associated with a 1.73-year lower onset age (95% confidence interval (CI) -2.80 to -0.66; adjusted R²=0.31; p=0.003). Total motor score was strongly associated with caregiver burden (Pearson r=-0.66; p=0.0001). Regression demonstrated that higher motor severity corresponded to higher ZBI-12 burden (β=0.27 per motor point; 95% CI 0.15-0.39; adjusted R²=0.41; p<0.001) [Table 5], and fitted polynomial line with 95% CI was generated on the associated scatter plots [figure3].

Conclusion: In this first national Iranian HD cohort, higher CAG repeat length was associated with earlier onset, and motor severity showed a large association with caregiver burden. These results support population-specific HD profiling and underscore caregiver burden as a clinically relevant correlate of motor progression, suitable for targeted counseling and care-resource planning.

Figure1. Age variables and CAG repetations.

Figure2. Fitted polynomial regression plots.

Table1. Summary of demographic statistics (n=113).

Table 2. Summary of continuous HD characteristics.

Table3. Summary of categorical HD characteristics.

References: 1. Scrimgeour, E.M., Huntington disease (chorea) in the middle East. Sultan Qaboos University Medical Journal, 2009. 9(1): p. 16.
2. van Lonkhuizen, P.J., et al., Quality of life, health-related quality of life, and associated factors in Huntington’s disease: a systematic review. Journal of Neurology, 2023. 270(5): p. 2416–2437.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/clinical-profile-and-key-correlates-of-genetic-load-motor-severity-and-caregiver-burden-in-an-iranian-huntingtons-disease-cohort/