The polyglandular autoimmune syndromes (PAS) comprise a wide spectrum of autoimmune disorders and are divided into a very rare juvenile (PAS type I) and a relatively common adult type with (PAS II) or without adrenal failure (PAS III). First clinical manifestation of PAS I usually occurs in childhood, whereas PAS II mostly occurs during the third and fourth decades. PAS I is caused by mutations in the autoimmune regulatory (AIRE) gene on chromosome 21 and is inherited in an autosomal recessive manner. Mutations in the AIRE gene result in defect proteins which cause autoimmune destruction of target organs by disturbing the immunological tolerance of the patients. Genetic testing may identify patients with PAS I, but not those with PAS II/III. For PAS II/III, susceptibility genes are known which increase the risk for developing autoimmune disorders, but must not be causative. These are certain HLA genes, the cytotoxic T lymphocyte antigen gene, and the protein tyrosine phosphatase non-receptor type 22 gene on chromosomes 6, 2 and 1 respectively. Actual diagnosis of PAS involves serological measurement of organ-specific autoantibodies and subsequent functional testing. Management of patients with PAS including their family relatives is best performed in centres with special expertise in autoimmune endocrine disorders.
George J Kahaly
Manuela Dittmar, Maximilian Ide, Michael Wurm and George J Kahaly
Polyglandular failure or autoimmunity (PGA) involves at least two endocrine diseases. Several genes may play a role in its etiology. This study analyzed 1) whether HLA-DRB1, HLA-DQB1, and MHC class I chain-related gene A (MICA) polymorphisms are associated in PGA and 2) whether PGA patients display stronger associations with these immune genes than patients with monoglandular autoimmunity (MGA).
HLA-DRB1, HLA-DQB1, and MICA alleles were analyzed in 73 patients with PGA, 283 with MGA, and 206 healthy controls. The HLA-DRB1 and HLA-DQB1 polymorphisms were determined with PCR-amplified DNA being hybridized with PCR-sequence-specific oligonucleotide probes. MICA microsatellites were typed by PCR amplification and fragment size analysis on a DNA sequencer.
HLA-DRB1*03 was strongly increased in patients with PGA (50.7%) versus both controls (21.8%, P c<0.0001; RR=2.32, 95% CI=1.62–3.33) and MGA (11.4%, P c<0.0001). HLA-DRB1*03 was highly prevalent in PGA patients with early versus late disease onset (P<0.05, logistic regression analysis). HLA-DRB1*04 allele carriers were more present in PGA versus controls (53.4% vs 22.4%, P c<0.0001, RR=2.38, 95% CI=1.68–3.38). Further, HLA-DQB1*02 was increased in PGA versus controls (P c<0.01), whereas HLA-DQB1*06 was decreased (P c<0.001). Patients with PGA showed more MIC A5.1 and less MIC A6 allele carriers than controls (NS). Presence of the MIC A5.1 allele was not associated with the HLA-DRB1*03 or HLA-DQB1 alleles.
HLA-DRB1*03 is a stronger genetic marker in PGA than in MGA, foremost in those with early disease onset.