Predicted

ψNCF-1/NCF-1 genotypes based on observed ΔGT/GTGT ratios in unaffected individuals and in carriers and patients with A47°CGD. We have identified unaffected control individuals with 3 different ratios of ΔGT/GTGT sequence in exon 2 of theψNCF-1/NCF-1 genes: 2:1, 1:1, or 1:2. The most likely explanation for these ratios is the existence in the population of 2 main extended haplotypes (see “Results and discussion”), giving rise to the ψNCF-1/NCF-1 genotypes shown. This figure reflects only the nucleotide sequence at the start of exon 2; it does not take into consideration other known differences between the gene and its pseudogenes. The solid and open bars represent GTGT-containing and ΔGT-containing (nonfunctional) genes, respectively. As depicted, the central gene on each chromosome is NCF-1. It is flanked by its 2 pseudogenes,16,18 which are either of Type I (ΔGT) or Type II (GTGT). In the majority of A47°CGD patients, both copies of NCF-1 contain the ΔGT mutation. Their carrier parents are heterozygous for the mutation, and although most have a ΔGT/GTGT sequence ratio of 5:1, as shown, approximately 10% would be predicted to show a ratio of 2:1 (see “Results and discussion”).