Association between C677T and A1298C MTHFR gene polymorphism and nonsyndromic orofacial clefts in the Turkish population: a case-parent study - Aida Semiç-Jusufagiç; Rıfat Bircan; Özhan Çelebiler; Melike Erdim; Nurten Akarsu; Nursel H Elçioğlu (The Turkish Journal of Pediatrics)