2-EXON SKIPPING DUE TO A POINT MUTATION IN P67-PHOX-DEFICIENT CHRONICGRANULOMATOUS-DISEASE

The cytosolic 67-kD protein in phagocytes (p67-phox) and B lymphocytes is one of essential components of the superoxide-generating system in these cells, and its defect causes an autosomal recessive type of chr onic granulomatous disease (CGD). We performed mutation analysis of p6 7-phox mRNA from a CGD patient who lacks the protein and found an in-f rame deletion from nucleotide 694 to 879, which corresponds to the ent ire sequence of exons 8 and 9. This sequence encodes one of two Src ho mology 3 domains and a part of proline-rich domain in p67-phox and lac k of these domains seem to have influenced stability of this protein. To know causative reason for the deletion, we analyzed genomic DNA for p87-phox using two sets of primers that covered exons 8 and 9 with ad jacent introns. The DNA fragments from the patient were shown to be sa me in length as those from control. However, the single-strand conform ation-polymorphism analysis of the fragments showed that a patient's s pecimen that included the splice junction of exon 9 exhibited differen t mobility from the control. By sequencing of the fragment, a homozygo us G to A replacement at position +1 of intron 9 was found to be a sol e mutation, which reduced the matching score of the splicing sequence to the consensus calculated according to the formula proposed by Shapi ro and Senapathy (Nucleic Acids Res 15:7155, 1987). The reduced matchi ng score at the splice doner site (5' splice site) of intron 9 and the original low matching score at the acceptor site (3' splice site) of intron 7 may explain the skipping of exon 8 and 9, and another predict ed mechanism is discussed on the basis of Shapiro and Senapathy's hypo thesis. (C) 1996 by The American Society of Hematology.