COL2A1 and osteoarthritis: In addition to ocular manifestations, the proportions of systemic abnormalities of STL1 were 100% flat midface (Figure 2), 54.5% (6/11) depressed nasal bridge, 27.3% (3/11) sensorineural deafness, 27.3% (3/11) osteoarthritis, and 9.1% (1/11) cleft palate (Table 3).