Hill, Harry R.

Abstract Description Common variable immunodeficiency (CVID) is a common inborn error of immunity, but a monogenic cause is rare. Biallelic loss-of-function pathogenic variants in the gene encoding BAFF-Receptor (TNFRSF13C) is one such cause. A common missense variant in BAFF-R, p.Pro21Arg, was proposed as contributing to the pathogenesis of non-monogenic CVID by Peiper et al. 2014 with an allelic frequency of 6.7% in controls versus 10.2% in CVID patients (OR 1.57, p = 0.0026) and Block et al. 2023 with an 11.36% allele frequency in CVID when compared to the Non-Finnish European population in the gnomAD database (OR = 1.316, p = 0.0145) and to an internal cohort of controls (OR = 1.316, p = 0.0458). Exact population composition matching is critical, as the frequency of this variant is highly variable even in Europe. We found the allelic frequency of BAFF-R p.Arg21Pro to be 10% from 90 non-familial CVID patients from the University of Utah Health Sciences Center, similar to Pieper et al. (10.2%) and Block et al. (11.36%), but comparing our Utah CVID patients to the 1000 Genomes project Utah Residents (CEU) with Northern and Western European Ancestry, which matches our CVID cohort (9.6% allelic frequency); we obtained an OR of 1.0468 (95% CI: 0.5309 to 2.0638; p = 0.8950). For further studies on BAFF-R p.Pro21Arg, we recommend closely matching the reference populations, and not using a broad European or other control populations. Topic Categories Translational and Interventional Immunology (TI)

Abstract CXXC5 is a member of the CXXC-type zinc finger epigenetic regulators. Various hematopoietic and nonhematopoietic roles have been assigned to CXXC5. In the present study, the role of Cxxc5 in myelopoiesis was studied using overexpression and short hairpin RNA-mediated knockdown in mouse early stem and progenitor cells defined as Lineage− Sca-1+c-Kit+ (LSK) cells. Knockdown of Cxxc5 in mouse progenitor cells reduced monocyte and increased granulocyte development in ex vivo culture systems. In addition, ex vivo differentiation and proliferation experiments demonstrated that the expression of Cxxc5 affects the cell cycle in stem/progenitor cells and myeloid cells. Flow cytometry-based analyses revealed that down-regulation of Cxxc5 leads to an increase in the percentage of cells in the S phase, whereas overexpression results in a decrease in the percentage of cells in the S phase. Progenitor cells proliferate more after Cxxc5 knockdown, and RNA sequencing of LSK cells, and single-cell RNA sequencing of differentiating myeloid cells showed up-regulation of genes involved in the regulation of cell cycle after Cxxc5 knockdown. These results provide novel insights into the physiologic function of Cxxc5 during hematopoiesis, and demonstrate for the first time that it plays a role in monocyte development.