Different clinical expressions in two families with Stargardt's macular dystrophy (STGD1)

Purpose: To describe the clinical expressions, with emphasis on electrophys iological examinations, in two Swedish families with Stargardt's macular dy strophy (STGD1). Methods. Two pairs of siblings with STGD1, for whom diagnosis had been conf irmed by genetic linkage to the ABCA4 gene region, were examined regarding visual acuity, kinetic perimetry, fundus photography, full-field ERG and mu ltifocal ERG (MERG). Possible disease-causing mutations were screened for b y DNA sequencing of selected regions of the ABCA4 gene. Results. All STGD1 patients, had visual acuity 0.07-0.1. The two families p resented different fundus appearances, MERGs and implicit times on. 30 Hz f licker white light full-field ERGs. Genetic analysis revealed one unique se quence variation in exon 19 of the ABCA4 gene, in one allele from the patie nts of one of the families. This point mutation causes the amino acid subst itution T972N in the ABCR protein. Conclusion. Two pairs of siblings with STGD1 presented two different expres sions of the disease regarding the distribution of the retinal dysfunction. One possible molecular explanation to the different clinical expressions m ay be the T972N substitution present in the ABCR protein in one of the STGD 1 families investigated.