How does muslim creationist explain our malfunctioning Vitamin C encoder in our genes?

Both creationists and evolutionist agree that there is indeed an easy way to differentiate evolution and design. When something is designed, vestigial remains do not exist. We do not have gas cars with remnant of broken coal tanks, for example. Yet we do have genes that can create vitamin C. The genes are broken due to some mutation turning it off. The broken genes and places where it's broken are similar with the places where similar genes are found on other primates, like orang utan, gorilla, and chimps. All those are exactly like predicted by evolution theory long before the facts are known. So what's a Muslim creationist's explanation of this?