Fig. 1: Genetic risk factors and disease penetrance in apparently sporadic ALS.
From: Penetrance and pleiotropy in ATXN2-related amyotrophic lateral sclerosis
Illustration of the relationship between the absolute disease risk conferred by a genetic risk factor for ALS and the likelihood of observing that risk factor in an apparently sporadic case of ALS. Factors associated with higher disease penetrance will tend to give rise to familial cases and only rarely be found in sporadic ALS. Conversely, factors associated with lower disease penetrance will more commonly be seen in sporadic ALS and will rarely be seen in familial ALS.
