monogenic disorder

NOUN
18 LETTERS · STARTS WITH M

monogenic disorder is a valid 18-letter word worth 24 points in Scrabble and 29 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
M3O1N1O1G2E1N1I1C3D2I1S1O1R1D2E1R1
3 + 1 + 1 + 1 + 2 + 1 + 1 + 1 + 3 + 0 + 2 + 1 + 1 + 1 + 1 + 2 + 1 + 1 =24 PTS
DOUBLE WORD → 48TRIPLE WORD → 72
MEANING

What does monogenic disorder mean?