Kasapkara ÇS, Yılmaz-Keskin E, Özbay-Hoşnut F, et al. An infant with an extremely rare cobalamin disorder: Methionine synthase deficiency and importance of early diagnosis and treatment. Turk J Pediatr. 2019;61(2):282-285. doi:10.24953/turkjped.2019.02.021