ABANDONED. Elves are Shadows and there are hunters?

[Zunacorn]

I'm trying to locate this book for a friend.
He is currently 20 and read this book quite a while ago so it is not a recent release.
He thinks the book is titled The Shadow Hunter or some variation.
This is what he remembers it being about, The story is about a brother and a sister, the brother is a half elf (elves are called shadows) and his sister is a human. They have an uncle who hunts elves (shadow hunter) they leave home and then loads of stuff happen.

Any help would be appreciated, thank you!

[Peter]

Possibly The Shadow Gate by Margaret Ball? I haven't read it myself, but it's one of my wife's favorites.

[Lobstergirl, au gratin]

Zara, is your friend still looking for this or was it found?

[RavensScar]

Could it maybe be one of Cassandra Clare books? She's written a couple of different series all set in the Shadowhunter world?

[Kate]

Cassandra Clare for the link to the author Luci suggested.

[Lobstergirl, au gratin]

Lobstergirl wrote: "Zara, is your friend still looking for this or was it found?"

No response in 2 years. Moving to Abandoned.