Abstract
Purpose: :
To describe the prevalence, clinical spectrum, and genotype of vitelliform macular dystrophy in Denmark.
Methods: :
Patients diagnosed previously with vitelliform macular dystrophy at a National Danish referral centre and classified according to clinical appearance and electro-oculogram (EOG), were offered a follow-up examination including multifocal ERG (mfERG), optical coherence tomography (OCT) and fundus autofluorescence photography (FAF). Molecular genetic analysis of BEST1 and RDS genes was performed by direct sequencing of PCR products. The phenotypes and genotypes were compared to a cohort of families described previously by us, together comprising all known families with vitelliform macular dystrophy in Denmark, enabling a minimum prevalence estimate.
Results: :
An initial survey including nine families with Best disease (BMD) led to the identification of five BEST1 missense mutations, four of which are novel: The mutations c.905A>C (p.Asp302Ala), c.295A>C (p.Asn99His), and c.58C>G (p.Leu20Val) were identified each in a single family, while c.904G>T(p.Asp302Asn) was identified in members of four different families. In addition, in one family with adult onset vitelliform macular dystrophy (AVMD) we identified a novel RDS mutation, in which one base is deleted and 45 bases are inserted, c.622delins45, leading to a frameshift and premature stop codon. No BEST1 or RDS mutations were detected in two index cases (one with Best disease and one with AVMD).Analysis of retinal function and structure revealed variable degrees of central function reduction, and structural alterations ranged between normal central retina to subretinal neovascularization with cystoid macular edema.In addition, 17 patients with AVMD, one patient with BMD and eight patients with vitelliform macular dystrophy but without a distinct clinical subtype have been identified, and DNA analyses and further clinical investigations are in progress.
Conclusions: :
Our data expand the mutation spectrum of BEST1 and RDS in patients with vitelliform macular dystrophy. The mutation p.Asp302Asn may represent a founder mutation in the Danish population. The combined data of the current study and those performed by us previously enable a minimum prevalence estimate of 1.8 per 100,000, with a proportion of 2:3 between BMD and AVMD, of vitelliform macular dystrophy in Denmark.
Keywords: macula/fovea • retinal degenerations: hereditary • electroretinography: clinical