OMIM ID:
Macular Dystrophy, Patterned 2
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Abnormal pigmentation of yellow, white, or black color accumulates in the central area of the macula. The deposition of pigment appears in the retinal pigment epithelium (RPE) level in a pattern more or less resembling the wings of a butterfly. The peripheral retina has diffuse pigment mottling. Drusen-like structures may be seen at the peripheral borders of the macular pigmentation. Visual fields are normal usually but there may be some decrease in central sensitivity.
However, this is a generalized retinal disorder as revealed by the abnormal mass response (decreased light/dark ratio) of the electrooculogram (EOG). Patients may not have visual symptoms until their late 20s or early 30s even though the pigmentation may be evident in the second decade. Color vision, dark adaptation and the ERG are normal. Younger patients may have normal vision.
Systemic Features
No systemic associations have been reported.
Genetics
Inheritance
This condition results from heterozygous mutations in the CTNNA1 gene (5q31). For a similar disorder see Macular Dystrophy, Patterned 1 (169150).
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