Prevalence and Diagnostic Spectrum of Generalized Retinal Dystrophy in Danish Children

PURPOSE: The aim of the present population-based cross-sectional study was to examine the prevalence and diagnostic spectrum of generalized retinal dystrophy in Danish children. METHODS: The Danish Registry for the Blind and Partially Sighted Children comprises all visually impaired children residing in Denmark aged 0-17 years. Among registered children, the primary diagnosis of generalized retinal dystrophy was assessed by chart review, including fundus photographs and electroretinograms. Age-specific data for live children in Denmark were retrieved from Statistics Denmark. RESULTS: Of the 1,204,235 Danish children aged 0-17 years on 1 October 2011, 2017 children were registered as visually impaired. Of these, 153 cases were attributed to generalized retinal dystrophy, corresponding to a prevalence of 13 per 100,000 children. The age-specific prevalence increased prominently with increasing age. In 43% of the children the eye condition was part of a syndrome, while the remaining 57% had eye disease only. The most common hereditary pattern was autosomal recessive (99 children, 66%). CONCLUSIONS: This epidemiological survey demonstrates that the prevalence of generalized retinal dystrophy in Danish children is 13 per 100,000, which is a considerable increase compared to the 9.8 per 100,000 reported by Rosenberg in 1988. The prevalence of Leber congenital amaurosis, Usher syndrome, and Bardet-Biedl syndrome doubled, which may be explained by a documented history of consanguinity in more than one third of the children. Many of the dystrophies are the subject of clinical intervention trials, and nation-wide epidemiological data can help assess the future need for treatment.