PON1 and amyotrophic lateral sclerosis: Furthermore, van Blitterswijk et al. [189], assessing the frequency of PON variants in 1118 sALS patients, 93 fALS patients, and 1240 control subjects of Dutch ancestry, detected no significant differences in mutational burden for rare variants or in allele frequencies of PON polymorphisms between patients and control subjects, concluding that mutations or polymorphisms in PON do not contribute to ALS susceptibility.