The CDIN1 gene encodes a novel restriction endonuclease, belonging to the Holliday junction resolvase family, and two missense mutations have been identified to be responsible for autosomal recessive congenital dyserythropoietic anemia type Ib (OMIM #615631) [17]. This evidence concerns the gene CDIN1 and Congenital dyserythropoietic anemia type I.