Identification of Single Nucleotide Polymorphisms in Myxovirus Resistance-1 (MxA) Gene Promoter (C/A at NT-123) Correlated with the Response of Hepatitis C Patients to Interferon, OLFAT G. SHAKER, SAMAR A. MARZOUK, AMR A. ZAHRA, HASSAN S. EL-SAYED and MAISA S. EL-RAZKY