OMIM ID:
Macular Dystrophy, Patterned 1
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Patterned dystrophies of the macula are clinically heterogeneous. It is common for different patterns to be seen among multiple members of a single family. They can also be different in the two eyes of the same individual. RPE changes can often be seen in the second decade of life but visual disturbances may not be noted until a decade or two later. The process is progressive and eventually macular function is severely depressed with vision in the range of 20/200. The pigmentary retinopathy occurs at the level of the RPE with the typical appearance of pigment but sometimes an accumulation of white or yellowish deposits is present. The pattern of changes may appear in a configuration resembling the wings of a butterfly, hence the name. However, vitelliform-like lesions have also been reported. Paracentral tritan color defects have been described.
Subfoveal choroidal neovascularization can occur.
While the ERG may show some diffuse photoreceptor dysfunction in the presence of normal vision, there is little to suggest a primary rod or cone abnormality. Dark adaptation is normal. Visual fields can reveal a small central scotoma and fluorescein angiography often shows window defects in the posterior pole.
Systemic Features
Simple patterned macular dystrophy is not associated with systemic disease.
Genetics
Inheritance
Pattern macular dystrophies are usually inherited as autosomal dominant conditions. Several mutations in separate genes have been linked to these disorders suggesting that this group is genetically as well as clinically heterogeneous.
Some families have mutations in the photoreceptor peripherin gene (PRPH2) at 6p21.1-cen (169150) whose gene product is active in the retina. It is important to the integrity and stability of the structures that contain light-sensitive pigments (e.g., photoreceptors). More than 100 mutations have been identified. The resultant phenotype can be highly variable, even within members of the same family but most affected individuals have some degree of pigmentary retinopathy within the macula or throughout the posterior pole. The altered gene product coded by mutations in PRPH2 often leads to symptoms beginning in midlife as a result of the slow degeneration of photoreceptors. This database contains at least 11 disorders in which PRPH2 mutations have been found.
A locus at 5q21.2-q33.2 containing heterozygous CTNNA1 mutations has been linked to a pattern dystrophy (Macular Dystrophy, Patterned 2) (608970).
As many as 25% of patients with myotonic dystrophy 1 (160900) and myotonic dystrophy 2 (602668) have a patterned pigmentary maculopathy.
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