Humans heterozygous for missense mutations p.S91C or p.E93G within the BMP4 prodomain (Figure 1A, C) display enhanced predisposition to colorectal cancer, micropthalmia, skeletal defects, brain abnormalities, cleft lip, and/or kidney dysgenesis (Bakrania et al., 2008; Lubbe et al., 2011; Suzuki et al., 2009; Weber et al., 2008), suggesting that these prodomain mutations interfere with the activity of BMP4 homodimers or BMP4/7 heterodimers. The gene discussed is BMP4; the disease is cleft lip.