A large in-frame deletion in IL12RB1. (A) Schematic representation of the wild-type IL-12Rβ1 chain containing 17 coding exons (Arabic numerals) encoding 662 amino acids, with a peptide leader sequence (L), extracellular domain (exons 2 to 13, EC), transmembrane domain (exon 14, TM), and an intracellular, cytoplasmic domain (exons 15 to 17, IC). The mutation found in P is also indicated (700 + 362_1619-944 del). The mature IL-12Rβ1 chain contains 5 fibronectin III (FNIII) domains shown in the bottom row in light gray. (B) Schematic representation of the mutant protein, lacking the sequences encoded by 6 of the exons (8 to 13) in the wild-type gene. The mutant protein contains 356 amino acids and only the first 2 FNIII domains of the extracellular domain but has intact transmembrane and intracellular domains. In the family tree, the patient is indicated by an arrow.