The purpose of our study was to verify the relationship between BTNL2 and HLA risk alleles for the susceptibility to sarcoidosis, and to assess whether the BTNL2 association is independent of the HLA risk alleles.
HLA-DRB1*04 seems to protect against overall sarcoidosis but appears to be a significant risk factor for ocular sarcoidosis as well as for other manifestations associated with HS.
In the group of patients with chronic sarcoidosisDRB1*11 (P=0.0219; OR=2.44), DRB1*15 (P=0.0414; OR=2.47) demonstrated statistically significant difference in comparison to controls only, while a lower frequency of DRB1*13 (P=0.0156; OR=0.24) in this group was statistically significant when compared to both patients with acute sarcoidosis and controls.
In a retrospective case-control study, TNF-alpha G-308A, TNF-alpha G-238A, lymphotoxin-alpha (LTA) and HLA-DRB1*03 were genotyped in 625 sarcoidosis patients.
ESAT-6 and katG presented by antigen-presenting cells expressing DRB1*1101-induced Th-1 responses from sarcoidosis T cells, thus providing a mechanistic insight for the association of HLA DRB1*1101 with sarcoidosis, and sarcoidosis T cell interaction with microbial antigens.
The CNV_ID 507, which was highlighted for its possible involvement in sarcoidosis because of its partly deletion of the BTNL2 gene, was tested for association in a cohort of 89 sarcoidosis patients and 89 matched controls, but our results indicated that CNV_ID 507 does not affect the genomic structure of BTLN2 as previously described.
The CNV_ID 507, which was highlighted for its possible involvement in sarcoidosis because of its partly deletion of the BTNL2 gene, was tested for association in a cohort of 89 sarcoidosis patients and 89 matched controls, but our results indicated that CNV_ID 507 does not affect the genomic structure of BTLN2 as previously described.
Our data suggest that the absence of a membrane anchored BTNL2 protein may increase genetic susceptibility to sarcoidosis and familial occurrence of the disease.
In addition, HLA DRB1*1101 and insecticide exposure at work was associated with extrapulmonary sarcoidosis, specifically cardiac sarcoidosis and hypercalcemia (p<0.05) and HLA DRB1*1101 and exposure to molds and musty odors was associated with pulmonary only sarcoidosis (P < 0.05).
Finally, multivariate analysis revealed that the CCR2 association was independent of HLA-DRB1*0301 in both Spanish (P = 0.02 vs. controls) and Swedish cohorts (P = 0.002 vs. non-Löfgren sarcoidosis, P = 0.001 vs. controls).
Butyrophilin-like 2 (BTNL2) is a butyrophilin family member with homology to the B7 costimulatory molecules, polymorphisms of which have been recently associated through genetic analyses to sporadic inclusion body myositis and sarcoidosis.
Genome-wide screening has conclusively identified linkage to chromosome 5q11and the development of sarcoidosis, and HLA genes and BTNL2 are susceptibility genes located in this region.
Initially, we studied the association of sarcoidosis with DQB1, and in the present study, we evaluated all amino acid variants of the HLA-DPB1, -DQB1, -DRB1, -DRB3, -DRB4 and -DRB5 genes to identify possible polymorphisms associated with the disease.
A recent study of sarcoidosis has provided evidence of an independent effect, associated with a truncating single nucleotide polymorphism (SNP) of a nearby gene, BTNL2.
BTNL2 haplotype 4, tagged by the rs2076530 G allele, also remained associated with non-Löfgren sarcoidosis after adjusting for HLA-DRB1 alleles (OR 0.37, P = 0.016).