Clinical and demographic factors and outcome of amyotrophic lateral sclerosis in relation to population ancestral origin

Eur J Epidemiol. 2016 Mar;31(3):229-45. doi: 10.1007/s10654-015-0090-x. Epub 2015 Oct 12.

Abstract

Background: To review how the phenotype and outcome of amyotrophic lateral sclerosis (ALS) change with variations in population ancestral origin (PAO). Knowledge of how PAO modifies ALS phenotype may provide important insight into the risk factors and pathogenic mechanisms of the disease.

Methods: We performed a systematic review and meta-analysis of the literature concerning differences in phenotype and outcome of ALS that relate to PAO.

Results: A review of 3111 records identified 78 population-based studies. The 40 that were included covered 40 geographical areas in 10 subcontinents. Around 12,700 ALS cases were considered. The results highlight the phenotypic heterogeneity of ALS at time of onset [age, sex ratio (SR), bulbar onset], age at diagnosis, occurrence of comorbidities in the first year after diagnosis, and outcome (survival). Subcontinent is a major explanatory factor for the variability of the ALS phenotype in population-based studies. Some markers of ALS phenotype were homogeneously distributed in western countries (SR, mean age at onset/diagnosis) but their distributions in other subcontinents were remarkably different. Other markers presented variations in European subcontinents (familial ALS, bulbar onset) and in other continents. As a consequence, ALS outcome strongly varied, with a median survival time from onset ranging from 24 months (Northern Europe) to 48 months (Central Asia).

Discussion: This review sets the scene for a collaborative study involving a wide international consortium to investigate, using a standard methodology, the link between ancestry, environment, and ALS phenotype.

Keywords: Amyotrophic lateral sclerosis; Continental population groups; Epidemiology; Ethnic groups; Phenotype.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Age of Onset
  • Amyotrophic Lateral Sclerosis / ethnology
  • Amyotrophic Lateral Sclerosis / genetics*
  • Amyotrophic Lateral Sclerosis / mortality
  • Continental Population Groups*
  • Disease Progression
  • Ethnic Groups
  • Genetic Predisposition to Disease*
  • Humans
  • Male
  • Phenotype
  • Prognosis
  • Registries
  • Sex Factors
  • Survival Rate
  • Treatment Outcome