Sequence analysis of the exon 1/intron 1 junction in the GTGT-containing allele of

NCF-1 in patient 2. The patient's G → T mutation at the +3 position of the 5′ (donor) splice site of intron 1 is easily observed after allele-specific (a/s) PCR to amplify only the GTGT-containing allele (arrow, upper right panel). The patient's father, who carried the ΔGT mutation on the other allele (not shown), had the normal G at this position. The patient's mother was heterozygous for the G → T mutation. In the patient's non-allele–specific (n/s) PCR product, the mutant T was barely detectable above background (red arrowhead, bottom right panel) and was dominated by the normal G arising in the ΔGT allele ofNCF-1 and in ψNCF-1 DNA.