Yes, HOMOGRAFT is a Scrabble word!

Letter values in Scrabble US: H 4, O 1, M 3, O 1, G 2, R 1, A 1, F 4, T 1.

Is it a valid word?

HOMOGRAFT is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

tissue or organ transplanted from a donor of the same species but different genetic makeup; recipient's immune system must be suppressed to prevent rejection of the graft