Comparison of the clinical and genetic features of amyotrophic lateral sclerosis across Cuban, Uruguayan and Irish clinic-based populations.

OBJECTIVES: This study compares the clinical characteristics of patients with amyotrophic lateral sclerosis (ALS) within three clinic-based populations from Cuba, Uruguay and Ireland and determines the impact of known ALS-associated genetic variants on phenotypic manifestations within the Cuban population. METHODS: Demographic and clinical information was collected on 115 Cuban, 220 Uruguayan and 1038 Irish patients with ALS attending national specialist clinics through 1996-2017. All Cuban patients and 676 Irish patients underwent next-generation DNA sequencing and were screened for the pathogenic C9orf72 repeat expansion. RESULTS: The mean age of onset was younger in the Cuban (53.0 years, 95% CI 50.4 to 55.6) and Uruguayan (58.2 years, 95% CI 56.5 to 60.0) populations compared with the Irish population (61.6 years, 95% CI 60.9 to 62.4). No differences in survival between populations were observed. 1.7 % (95% CI 0.6 to 4.1) of Cubans with ALS carried the C9orf72 repeat expansion compared with 9.9% (95% CI 7.8 to 12.0) of Irish patients with ALS (p=0.004). Other known variants identified in the Cuban population included ANG (one patient), CHCHD10 (one patient) and DCTN1 (three patients). CONCLUSIONS AND RELEVANCE: This study is the first to describe the clinical characteristics of ALS in Cuban and Uruguayan populations and report differences between the Cuban and Irish genetic signature in terms of known ALS-associated genetic variants. These novel clinical and genetic data add to our understanding of ALS across different and understudied populations.

The Latin American Epidemiology Network for ALS (Laenals).

Background: There is evolving evidence of non-uniform distribution of ALS worldwide, with apparently lower incident and prevalent rates outside populations of European origin. However, the phenotype, survival and environmental risk in populations of mixed ancestral origin have not been well established. Large scale population based studies of incidence, prevalence, phenotype and risk factors in admixed populations are necessary to determine the true demography of ALS, and to test the hypothesis of differential risk and phenotype in populations of mixed ancestry. Methods: The Latin American Epidemiological Network of ALS (LAENALS) has been established to perform a comparative analysis of ALS epidemiology between three different Latin American populations (Cuba, Uruguay and Chile), and to test the hypothesis that the demographics, phenotype and outcome of ALS are influenced by ancestral origin, and that environmental and occupational risk factors differ across different ethnicities due to subtle differences in gene- environmental interactions. Recognition and interrogation of these differences is an important step toward novel therapeutic approaches and personalized medicine for all ALS both in the US, and worldwide. Discussion: This work will enable direct and detailed comparative studies between different ancestral populations with varying degrees of admixture, with facility for comparison with a large European reference dataset for ALS, and will provide a unique and rich dataset of admixed populations for later comparative genomic studies.