MASP1 and ptosis: Similarly, sequence variants in MASP1 (3q27.3) encoding a serine protease having an essential role in the innate and adaptive immune response have been associated with 3MC syndrome 1 characterized by widely spaced eyes (hypertelorism), a narrowing of the eye opening (blepharophimosis), droopy eyelids (ptosis) and highly arched eyebrows.