TTR and amyotrophic lateral sclerosis: serpin A1, which was identified in three studies, was increased in amyotrophic lateral sclerosis in two studies137,140 but decreased in the third.141 Additionally, TTR was reported as significantly decreased in amyotrophic lateral sclerosis in three studies113,142 but increased in a fourth study.143 The publications included in this meta-analysis used a variety of different MS technologies, which may explain the inconsistency in the results.