The Major Histocompatibility Complex Gene Region and Sarcoidosis Susceptibility in African Americans

• Published in: American journal of respiratory and critical care medicine Vol. 167; no. 3; pp. 444 - 449
• Main Authors: Rybicki, Benjamin A, Maliarik, Mary J, Poisson, Laila M, Sheffer, Roberta, Chen, Kang Mei, Major, Marcie, Chase, Gary A, Iannuzzi, Michael C
• Format: Journal Article
• Language: English
• Published: New York, NY Am Thoracic Soc 01-02-2003; American Lung Association; American Thoracic Society
• Subjects: African Americans; Antigens; Biological and medical sciences; Biopsy; Black or African American; Black People - genetics; Chromosomes; Genes; Genetic Predisposition to Disease; Humans; Leukocytes; Major Histocompatibility Complex - genetics; Medical sciences; Microsatellite Repeats; Nuclear family; Parents & parenting; Sarcoidosis; Sarcoidosis, Pulmonary - genetics; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Human; leukocyte antigens; Gene; Sarcoidosis; Systemic disease; Negroid; African Americans; family; Genetic determinism; Histocompatibility; linkage disequilibrium
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.2112060

Investigators have intensively evaluated the major histocompatibility (MHC) complex for sarcoidosis susceptibility genes with the majority of reports implicating the human leukocyte antigen (HLA)-DRB1 gene. Because most studies have been performed in white and Asian populations, we sought to determine which MHC genes might be risk factors for sarcoidosis in African Americans. We genotyped six microsatellite markers spanning 11.6 megabases that overlapped the MHC region on chromosome 6p21-22 in 225 nuclear families ascertained by African American probands with a history of sarcoidosis. Using a family-based association methods approach, we performed multiallelic tests of association between each marker and sarcoidosis. A statistically significant association was detected between sarcoidosis and the DQCAR marker (p = 0.002) less than two kilobases telomeric from the HLA-DQB1 gene. Typing two additional markers in this region revealed that DQCAR-G51152 haplotypes, spanning a 38-kilobase region across the HLA-DQB1 gene, were associated with sarcoidosis on a global level (p = 0.022). Analysis of individual DQCAR and G51152 alleles showed that the DQCAR 178 (expected = 21.0; observed = 10; p = 0.0005) and G51152 217 (expected = 25.6; observed = 14; p = 0.0009) alleles were transmitted to affected offspring less often than expected; whereas the DQCAR 182 allele was transmitted more often than expected (expected = 52.6; observed = 66; p = 0.002). Our results indicate that HLA-DQB1 and not HLA-DRB1 plays an important role in sarcoidosis susceptibility in African Americans. Identification of the specific HLA-DQB1 alleles that influence sarcoidosis susceptibility in African Americans and the study of their antigenic-binding properties may reveal why African Americans suffer disproportionately from this disease.