2.2 DNA extraction
Five ml of whole blood sample was collected from the proband (III-3) and the other family members (Ⅰ-2, Ⅱ-1, Ⅱ-2, Ⅱ-3, Ⅱ-4, Ⅱ-5, Ⅱ-6, Ⅲ-1 and Ⅲ-2) individually using EDTA-anticoagulant vacuum blood collection tubes. Genomic DNA was extracted from peripheral blood leukocytes of the collected blood samples using a DNA extraction kit (TianGen, Beijing, China) according to the manufacturer’s instructions. And the DNA extracts were stored at −20℃ for analysis later.