ECE2014 Poster Presentations Adrenal cortex (56 abstracts)
21-hydroxylase autoantibody positivity is influenced by HLA genotype in South African patients with Addison's disease
Ian Ross 1 , Sunanda Babu 2 , Liping Yu 2 , Taylor Armstrong 2 , Li Zhang 2 , Desmond Schatz 3 , Alberto Pugliese 4 , George Eisenbarth 2 & Peter Baker 2
1University of Cape Town, Cape Town, South Africa; 2Barbara Davis Centre, Denver, Colorado, USA; 3University of Florida, Gainesville, Florida, USA; 4University of Miami, Coral Gables, Florida, USA.
Background: Data examining HLA associations in Addison’s disease (AD) from South Africa (SA) are limited. We wished to determine the HLA in South African AD patients either positive or negative for 21 hydroxylase autoantibodies (21 OH-AA) and matched healthy controls, hypothesising that certain HLA alleles could predominate, but there may be differences from Western countries.
Methods: SA patients (n=73) were enrolled as part of a nationwide study of AD and matched for 78 healthy control subjects’ gender and ethnicity. HLA alleles were determined using DNA-based typing for DQA1, DQB1, and DRB1 class II antigens, as well as HLA-B class I antigens. Serum autoantibodies were tested at the Barbara Davis Center.
Results: There were 40 patients who were 21 OH-AA positive and 33 who were negative. In all SA-AD HLA-DR3, DR4, the combination DR3/DR4 predominated vs controls (P≤0.01). This was more pronounced in 21OH-AA+ SA-AD vs controls with nearly 65% of AD individuals having DR3 or DR4 haplotypes, vs only 38% of controls (P=1.9×10−3). In addition, the DR3/4 genotype, and HLA-B8 were much more common (P≤10−3 for both comparisons). DQB1*0202 was associated with protection from AD in 21 OH-AA positive patients only, but not 21 OH-AA negative patients, despite allelic similarities with high risk DQB1*0201. HLA-B8 did not have an independent effect apart from the DR3 haplotype. HLA-B7 was also higher in the 21 OH-AA+ vs 21OH-AA negative and control populations.
Conclusions: SA-AD 21OH-AA+ patients manifest with similar HLA alleles with Western countries. HLA class II haplotypes distinguish AD risk vs controls. Distinct differences in HLA were present in autoantibody positive patients, negative patients, and controls, necessitating both 21OH-AA and HLA genotype in clinical risk assessment of patients with AD. Differences in class II haplotypes are also potential contributors to the development and/or persistence of 21 OH-AA.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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