SYSTEMATIC SCREENING FOR RNA WITH SKIPPED EXONS - SPLICING MUTATIONS OF THE FERROCHELATASE GENE

A systematic method was designed to screen a large population of patie nts with erythropoietic protoporphyria (EPP) for aberrant ferrochelata se RNA with skipped exons. The method utilizes the new junction sequen ce created by exon skipping as the probe to detect such RNA species. I n 7 of 17 EPP families, an aberrant ferrochelatase RNA with one exon m issing was observed. Two previously unreported splicing mutations were also identified in 2 EPP families. One was a G >> T transversion at t he +1 position of the acceptor site of intron 8, causing exon 9 to be skipped during RNA splicing. Both the patient and her father were foun d to be heterozygous for this mutation. In another family, an A >> G t ransition at the +3 position of the donor site of intron 10 was identi fied, associated with exon 10 skipping during RNA splicing. Both the p atient and her father were heterozygous for this mutation.