HBG2 and Schnyder corneal dystrophy: Based on Exome Aggregation Consortium (ExAC) database of pathogenic mutation [25], we found no significant difference in the number of pathogenic variants in both SCD patients with high or low HbF levels in genes (BCL11A), proto-oncogene, transcription factor (MYB), Homeobox A9 (HOXA9), hemoglobin subunit gamma 2 (HBG2), Kruppel like factor 1 (KLF1), zinc finger and BTB domain containing 7A (ZBTB7A) in chromosomes 2, 6, 7, 11, 12 and 19, respectively.