Systemic sclerosis (SSc) is an autoimmune disease that shows one of the highest mortality rates among rheumatic diseases. We perform a large genome-wide association study (GWAS), and meta-analysis with previous GWASs, in 26,679 individuals and identify 27 independent genome-wide associated signals, including 13 new risk loci. The novel associations nearly double the number of genome-wide hits reported for SSc thus far. We define 95% credible sets of less than 5 likely causal variants in 12 loci. Additionally, we identify specific SSc subtype-associated signals. Functional analysis of high-priority variants shows the potential function of SSc signals, with the identification of 43 robust target genes through HiChIP. Our results point towards molecular pathways potentially involved in vasculopathy and fibrosis, two main hallmarks in SSc, and highlight the spectrum of critical cell types for the disease. This work supports a better understanding of the genetic basis of SSc and provides directions for future functional experiments.

We conducted a large-scale genetic analysis on giant cell arteritis (GCA), a polygenic immune-mediated vasculitis. A case-control cohort, comprising 1,651 case subjects with GCA and 15,306 unrelated control subjects from six different countries of European ancestry, was genotyped by the Immunochip array. We also imputed HLA data with a previously validated imputation method to perform a more comprehensive analysis of this genomic region. The strongest association signals were observed in the HLA region, with rs477515 representing the highest peak (p = 4.05 × 10(-40), OR = 1.73). A multivariate model including class II amino acids of HLA-DRβ1 and HLA-DQα1 and one class I amino acid of HLA-B explained most of the HLA association with GCA, consistent with previously reported associations of classical HLA alleles like HLA-DRB1(∗)04. An omnibus test on polymorphic amino acid positions highlighted DRβ1 13 (p = 4.08 × 10(-43)) and HLA-DQα1 47 (p = 4.02 × 10(-46)), 56, and 76 (both p = 1.84 × 10(-45)) as relevant positions for disease susceptibility. Outside the HLA region, the most significant loci included PTPN22 (rs2476601, p = 1.73 × 10(-6), OR = 1.38), LRRC32 (rs10160518, p = 4.39 × 10(-6), OR = 1.20), and REL (rs115674477, p = 1.10 × 10(-5), OR = 1.63). Our study provides evidence of a strong contribution of HLA class I and II molecules to susceptibility to GCA. In the non-HLA region, we confirmed a key role for the functional PTPN22 rs2476601 variant and proposed other putative risk loci for GCA involved in Th1, Th17, and Treg cell function.

Immunoglobulin-A vasculitis (IgAV) is classically a childhood small-sized blood vessel vasculitis with predominant involvement of the skin. Gastrointestinal and joint manifestations are common in patients diagnosed with this condition. Nephritis, which is more severe in adults, constitutes the most feared complication of this vasculitis. The molecular bases underlying the origin of IgAV have not been completely elucidated. Nevertheless, several pieces of evidence support the claim that genes play a crucial role in the pathogenesis of this disease. The human leukocyte antigen (HLA) region is, until now, the main genetic factor associated with IgAV pathogenesis. Besides a strong association with HLA class II alleles, specifically HLA-DRB1 alleles, HLA class I alleles also seem to influence on the predisposition of this disease. Other gene polymorphisms located outside the HLA region, including those coding cytokines, chemokines, adhesion molecules as well as those related to T-cells, aberrant glycosylation of IgA1, nitric oxide production, neoangiogenesis, renin-angiotensin system and lipid, Pyrin and homocysteine metabolism, may be implicated not only in the predisposition to IgAV but also in its severity. An update of the current knowledge of the genetic component associated with the pathogenesis of IgAV is detailed in this review.

Cell migration is one of the earliest events required for development of the testis. Migration occurs only in XY gonads downstream of Sry expression and is required for the subsequent epithelialization of testis cords. Using organ culture experiments and tissue recombination, we and others speculated that peritubular myoid (PTM) cells were among the migratory cells and were likely the cell type required for cord formation. However, because no unique marker was found for PTM cells, their positive identification during or after migration remained unclear. α-Smooth Muscle Actin (αSma; approved gene symbol Acta2), a classic marker of adult PTM cells,is expressed broadly in testis interstitial cells at E12.5, and becomes highly enriched in PTM cells by E15.5–16.5. We used a novel transgenic line expressingEYFP under the control of an αSma promoter to determine whether αSma-EYFP positive cellsmigrate into the gonad. Surprisingly, mesonephroi expressing αSma-EYFP do not contribute any EYFP positive cells to XY gonads when used as donors in recombination cultures. These results indicate that αSma-EYFP cells do not migrate into the gonad during the critical window of sex determination and cannot be the migrating cell type required for testis cord formation. Our results suggest that PTM cells, and most other interstitial lineages, with the exception of endothelial cells, are induced within the gonad. These experiments suggest that endothelial cells are the migrating cell type required for epithelialization of testis cords.