In Reply We appreciate the comments of Riancho et al on our article1 investigating the association of retinol-binding protein 4 (RBP4) concentrations with the amyotrophic lateral sclerosis (ALS) risk and prognosis in the ALS registry Swabia. In their letter, they pointed out important clinical aspects and suggested that the causes of the disease could vary depending on the clinical characteristics of ALS and should be considered.