HMGCS2 and Hartnup disease: These included 2 cases (18.2%, n = 2/11) of methylmalonic encephalopathy followed by 1 case (9.1%, n = 1/11) each of carnitine acylcarnitine translocase deficiency, Hartnup disorder, HMG-CoA lyase deficiency, HMG-CoA synthase-2 deficiency, maple syrup urine disease type IA, methylmalonic aciduria, methylmalonic aciduria type mut (0), ornithine transcarbamylase deficiency, and tyrosinemia type 1, respectively (Additional file 3).