PRSS56 and microphthalmia: To date, five genetic loci (Table 3) were reported to be linked to nanophthalmos: NNOS 2 is related to mutations in membrane frizzled-related protein (MFRP); NNOS 4 is related to mutations in TMEM98; MCOP6 is related to mutations in serine protease 56 (PRSS56) [50, 51]; and NNOS 1 and 3 were localized to chromosomal regions only (11p12-11q13 and 2q11-q14) [26, 29, 30].