crowed discs

Nanophthalmos Plus Syndrome

Clinical Characteristics

Ocular Features:

This is a recently described type of nanophthalmos with characteristic clinical features plus retinal degeneration and optic disc drusen. Hyperopia is common and, like another recessive form of nanophthalmos (267760), patients have a progressive retinal dystrophy beginning with granular and mottled RPE changes and progressing to a bone spicule pattern resembling retinitis pigmentosa. No synechiae have been reported in this syndrome however. Macular retinoschisis and cystic changes with reduced foveal reflexes are commonly present. The anterior chamber and angles are narrow but no reported cases have had angle closure glaucoma such as frequently occurs in other forms of nanophthalmos (267760, 609549, 600165, 611897). Drusen of the optic nerve head can be demonstrated by ultrasound. Scleral and choroidal thickening are usually present. There is progressive deterioration of photoreceptors beginning with rod dysfunction and eventually involving cones as documented on ERG recordings. Nyctalopia and visual difficulties begin in childhood and the visual field is concentrically constricted. Visual acuity is in the range of 20/100 to 20/200.

Systemic Features:

No systemic abnormalities have been reported.

Genetics

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.

Pedigree:

Autosomal recessive

Treatment

Treatment Options:

Angle closure glaucoma is a constant threat in some nanophthalmic conditions but has not been reported in this disorder. Nevertheless, it may be prudent to consider prophylactic iridotomies in high risk cases.

References

Article Title:

Compound heterozygosity for a novel and a recurrent MFRP gene mutation in a family with the nanophthalmos-retinitis pigmentosa complex

Zenteno JC, Buentello-Volante B, Quiroz-Gonzalez MA, Quiroz-Reyes MA. Compound heterozygosity for a novel and a recurrent MFRP gene mutation in a family with the nanophthalmos-retinitis pigmentosa complex. Mol Vis. 2009 Sep 5;15:1794-8.

PubMed ID:

19753314

A novel mutation confirms MFRP as the gene causing the syndrome of nanophthalmos-renititis pigmentosa-foveoschisis-optic disk drusen

Crespi J, Buil JA, Bassaganyas F, Vela-Segarra JI, Diaz-Cascajosa J, Ayala-Ramirez R, Zenteno JC. A novel mutation confirms MFRP as the gene causing the syndrome of nanophthalmos-renititis pigmentosa-foveoschisis-optic disk drusen. Am J Ophthalmol. 2008 Aug;146(2):323-328.

PubMed ID:

18554571

A new autosomal recessive syndrome consisting of posterior microphthalmos, retinitis pigmentosa, foveoschisis, and optic disc drusen is caused by a MFRP gene mutation

Ayala-Ramirez R, Graue-Wiechers F, Robredo V, Amato-Almanza M, Horta-Diez I, Zenteno JC. A new autosomal recessive syndrome consisting of posterior microphthalmos, retinitis pigmentosa, foveoschisis, and optic disc drusen is caused by a MFRP gene mutation. Mol Vis. 2006 Dec 4;12:1483-9.

PubMed ID:

17167404

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