GDF3 and amyotrophic lateral sclerosis: GDF3 is a member of growth differentiation factors, which constitutes a subfamily of the transforming growth factor-β (TGF-β) superfamily.42,43GDF3 has been identified as an inhibitor of bone morphogenetic proteins (BMPs).44 BMPs play a key role in inducing the formation of cartilage, bone, and skeletal muscle.45,46 The participation of GDF3 in the development of bone and cartilage, acting as an inhibitor of BMPs, may provide insights into its potential association with ALS.