**2.2 DNA isolation**

Genomic DNA was isolated from peripheral WBC by using DNA Kit (Thermo Scientific Gene JET Genomic DNA Purification Kit) (Qiagen, USA). DNA concentrations were measured using Gene Nano Drop (Biochrom, England), which occured in the biology laboratory at Alassad University Hospital in Damascus, Syria. Repeated thawing and freezing of the samples were avoided.
