2.2 DNA extraction
Five ml of whole blood sample was individually taken from the proband
and his parents, and 10 ml of the amniotic fluid was collected from the
pregnant mother in an amniocentesis test under ultrasound. Genomic DNA
was extracted from obtained blood samples or amniotic fluid using a DNA
extraction kit (TianGen, Beijing, China) and stored at −20℃ for analysis
later.