For Chatham mutation, PCR products were incubated with Bstx1 restriction enzyme (Fennentas Co, Russia) for 17 hours at 37°C. Digested products were electrophoresed on 2% agarose gel for 2 hours, and the image of each gel was captured afterwards. In cases of no Chatham mutation and after enzymatic digestion, 78-bp and 130-bp bands are visible, and in the presence of mutation, 130-bp band will be cleaved into 100-bp and 30-bp bands (Fig.2).