Excises hypoxanthine, a deamination product of adenine, from double-stranded DNA. Acts on double-stranded DNA containing G/I, T/I, A/I and C/I base pairs, but not on single-stranded inosine-containing DNA. Has also minor xanthine DNA glycosylase activity. Lacks any detectable uracil-DNA glycosylase activity. Belongs to the uracil-DNA glycosylase (UDG) superfamily. Type 6 (HDG) family.