Characterization of the patient's CD18 mutations. The patient was determined to be a compound heterozygote with 2 distinct mutations. (A) A diagram of the first mutation defined, a 36-base pair deletion in exon 12 (1622del36), predicting a deletion of 13 aa residues and insertion of a new tryptophan residue (net loss of 12 aa residues) at the 3′ end of the third cysteine-rich repeat domain of the CD18 extracellular stalk region (C541_G553delinsW) and referred to in the text as “mut-1.” (B) A diagram of the second mutation defined, a nonsense mutation creating a stop codon in exon 15 (2200G>T), predicting a 36-aa truncation of the CD18 cytoplasmic domain (E734X) and referred to in the text as “mut-2.” A schematic diagram of the CD18 protein precursor is shown in panel C, including the locations of mut-1 and mut-2, as indicated by asterisks.