We decided to exclude certain disorders where ID is no longer considered one of the main clinical features (e.g., Succinyl-CoA:3-oxoacid-CoA transferase (SCOT) deficiency, Riboflavin transporter deficiency (RTD)), or where treatment was shown to be ineffective in larger studies (e.g., Sanfilippo syndrome A-D). This evidence concerns the gene OXCT1 and renal tubular dysgenesis of genetic origin.