MFRP and retinal degeneration: Besides six MFRP mutations identified in patients with NNO2 or posterior microphthalmia with retinal degeneration, many non-pathological variations were observed in MFRP. Among the six causative MFRP mutations, four of them were homozygous (c.498insC, c.498delC, c.524T>C, and c.1143insC), and two of them were compound heterozygous (c.492delC and c.545C>T).