polygenic disorder

NOUN
18 LETTERS · STARTS WITH P

polygenic disorder is a valid 18-letter word worth 27 points in Scrabble and 31 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
P3O1L1Y4G2E1N1I1C3D2I1S1O1R1D2E1R1
3 + 1 + 1 + 4 + 2 + 1 + 1 + 1 + 3 + 0 + 2 + 1 + 1 + 1 + 1 + 2 + 1 + 1 =27 PTS
DOUBLE WORD → 54TRIPLE WORD → 81
MEANING

What does polygenic disorder mean?