Phenotypic spectrum of autosomal recessive cone-rod dystrophies caused by mutations in the ABCA4 (ABCR) gene.

Objective: To describe the phenotype of 12 patients with autosomal recessive or isolated cone-rod types of progressive retinal degeneration (CRD) caused by mutations in the ABCA4 gene.

Methods: The charts of patients who had originally received a diagnosis of isolated or autosomal recessive CRD were reviewed after molecular analysis revealed mutations in the ABCA4 gene.

Results: In two of the patients both the photopic and scotopic electroretinogram were nonrecordable. In the remainder, the photopic cone b-wave amplitudes appeared to be more seriously affected than the scotopic rod b-wave amplitudes. Although the clinical presentation was heterogeneous, all patients experienced visual loss early in life, impaired color vision, and a central scotoma. Fundoscopy revealed evidence of early-onset maculopathy, sometimes accompanied by involvement of the retinal periphery in the later stages of the disease.

Conclusions: Mutations in the ABCA4 gene are the pathologic cause of the CRD-like dystrophy in these patients, and the resultant clinical pictures are complex and heterogeneous. Given this wide clinical spectrum of CRD-like phenotypes associated with ABCA4 mutations, detailed clinical subclassifications are difficult and may not be very useful.