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A preliminary report on a DNA-based screening method for retinitis pigmentosa. A trial on a west Australian
P Rakoczy1, S Di Grandi, L Kelloway
1Department of Molecular Biology, Centre for Ophthalmology and Visual Science, Lions Eye Institute, 2 Verdun Street, Nedlands 6009, Western Australia.
Purpose And Background:
Recent reports have linked numerous point mutations in the human genome to retinitis pigmentosa (RP), suggesting that in the near future molecular biology based genetic counselling for patients with RP might become a reality. In this paper we assess the viability of a DNA-based screening method for RP. Specifically, we screened rhodopsin and the beta-subunit of phosphodiesterase (B-PDE) genes for the presence of abnormalities in West Australian RP patients.
Methods:
Blood was collected from 27 patients. Leukocyte DNA was extracted from patients and 50 randomly selected controls. Exons 1-19 and 21 of B-PDE and exons 1, 3 and 5 of rhodopsin were analysed using single-strand conformational polymorphism (SSCP) following DNA amplification. The nature of anomalies detected by SSCP was classified with DNA sequencing.
Results:
In RP patient samples, we found anomalous bands in exons 5, 9, 10, 15 and 16 and 17 of B-PDE and in exons 1 and 3 of rhodopsin genes. In B-PDE none of the anomalous bands represented mutations. Some of the anomalous bands in the rhodopsin gene, however, corresponded to silent mutations at nucleotide positions 269 and 3982 in four patients.
Conclusions:
In this study we have demonstrated that SSCP in combination with DNA sequencing is a powerful tool to identify new mutations and to provide information for a 'mutational panel' for future screening.