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We describe a spontaneously derived mouse line that completely failed to induce Ig class switching in vitro and in vivo. The mice inherited abolished IgG serum titers in a recessive manner caused by a spontaneous G→A transition mutation in codon 112 of the aicda gene, leading to an arginine to histidine replacement (AIDR112H). Ig class switching was completely reconstituted by expressing wild-type AID. Mice homozygous for AIDR112H had peripheral B cell hyperplasia and large germinal centers in the absence of Ag challenge. Immunization with SRBCs elicited an Ag-specific IgG1 response in wild-type mice, whereas AIDR112H mice failed to produce IgG1 and had reduced somatic hypermutation. The phenotype recapitulates the human hyper-IgM (HIGM) syndrome that is caused by point mutations in the orthologous gene in humans, and the AIDR112H mutation is frequently found in HIGM patients. The AIDR112H mouse model for HIGM provides a powerful and more precise tool than conventional knockout strategies. [ABSTRACT FROM AUTHOR]

Adrenal Cushing's syndrome is caused by excess production of glucocorticoid from adrenocortical tumors and hyperplasias, which leads to metabolic disorders. We performed whole-exome sequencing of 49 blood-tumor pairs and RNA sequencing of 44 tumors from cortisol-producing adrenocortical adenomas (ACAs), adrenocorticotropic hormone-independent macronodular adrenocortical hyperplasias (AIMAHs), and adrenocortical oncocytomas (ADOs). We identified a hotspot in the PRKACA gene with a L205R mutation in 69.2% (27 out of 39) of ACAs and validated in 65.5% of a total of 87 ACAs. Our data revealed that the activating L205R mutation, which locates in the P+l loop of the protein kinase A (PKA) catalytic subunit, promoted PKA substrate phosphorylation and target gene expression. Moreover, we discovered the recurrently mutated gene D0T1L in AIMAHs and CLASP2 in ADOs. Collectively, these data highlight potentially functional mutated genes in adrenal Cushing's syndrome. [ABSTRACT FROM AUTHOR]