Clinical Characteristics
Ocular Features
The axial length ranges from 17.55 to 19.28 mm with a mean of 18.13 mm. The mean refractive error was +9.88 in one reported family but ranged from +7.25 to +13.00. More than half of reported patients have developed angle closure glaucoma. Patients are at risk for strabismus and amblyopia. Choroidal detachments are often seen in nanophthalmic eyes.
Histological studies on full thickness sclerotomy tissue from a nanophthalmic eye showed frayed and split collagen fibrils with lightly stained cores predominantly in the sclera and episcleral regions which may contribute to the anatomical changes.
Systemic Features
None have been reported.
Genetics
Inheritance
No mutation has been described but this autosomal dominant condition maps to 11p.
Another type of autosomal dominant nanophthalmos (NNO3) (611897) maps to 2q22-q14, and yet another, nanophthalmos AD, results from mutations in TMEM98.
Nanophthalmos may also be inherited in an autosomal recessive pattern.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission