Nanophthalmos type 2 (NNO2; #609549) and isolated microphthalmia type 6 (MCOP6; OMIM #613517) are autosomal recessive conditions associated with pathogenic variants in the membrane frizzled-related protein (MFRP) [8] and serine protease 56 (PRSS56) genes [9], respectively [10]. Here, PRSS56 is linked to nanophthalmos 2.