3.3 | Mutation studies
Using selective PID panel testing, all patients were found to have mutations in the CD40LG gene (Table 3 ) and were diagnosed with XHIGM. In this cohort, hemizygous mutations were found in five patients (P1, P2, P3, P4, and P7), and microdeletions were found in two others (P5 and P6). The mutations were mostly inherited via the maternal lineage (P1, P2, P5, P6, and P7). However, parents of P3 and P4 did not carry the same mutation as their children. Two novel hemizygous mutations (c.424_436del and c.488delT) in exon 5 were detected in P1 and P3, respectively, whereas a novel hemizygous mutation (c.92_104del) in exon 1 was found in P2. These mutations have never been reported in gnomAD and were predicted to be disease-causing mutations using PolyPhen2, Mutation Taster, PROVEAN, and SIFT software.