Whole genomic DNA, used as a template
for PCR, was extracted from the livers of all
individuals, following a standard phenolchloroform-
isoamylalcohol protocol (Sambrook
and Russell, 2001), with slight modification.
Briefly, after homogenization, the tissue was
digested at 37°C overnight using 25 μg/μL
proteinase K in 0.5% (w/v) SDS in STE buffer
(0.1 M NaCl, 50 mM Tris and 1 mM EDTA, pH
8.0). Then, the mixture was extracted with phenolchloroform-
isoamylalcohol (25:24:1) and the
DNA was precipitated with 0.05 volume of 0.2 M
NaCl and 2.5 volume of 100% ethanol. After
washing in 70% ethanol, the genomic DNA was
air-dried and resuspended in TE buffer.