This is an autosomal recessive disorder caused by mutations in the membrane frizzled-related protein coding gene MFRP (11q23) expressed in retinal tissue. Both homozygous and compound heterozygous mutations have been described. It seems to be allelic to another nanophthalmos condition without retinal pigmentary degeneration which is caused by different mutations in MFRP (NNO2 609549). However, there is considerable clinical overlap of the several nanophthalmos conditions and it is possible that this is simply clinical heterogeneity within the same disease.
A syndromic form (MCOP5) of autosomal recessive microphthalmia with retinitis pigmentosa (611040) is also caused by mutations in MFRP and may be the same disorder.
For other forms of nanophthalmos see: 267760, 609549, 600165, 611897.