Polyglandular Autoimmune syndrome Type 3 (PAS 3)
Prepared by: Daniela Cihakova MD, PhD|
Definition: In PAS-3, autoimmune thyroiditis occurs with another organ-specific autoimmune disease, but not with autoimmune adrenalitis. Other autoimmune diseases can include diabetes mellitus, pernicious anemia, vitiligo, alopecia, myasthenia gravis, and Sjögren’s syndrome.
Symptoms: Depends on the organ affected.
Diagnosis: Depends on which organ is affected. Treatment involves life-long follow up and screening for another glandular failure in patients already diagnosed with PAS-3.
Types: PAS-3 can be further classified into 3 categories:
PAS-3A = autoimmune thyroiditis with immune-mediated diabetes mellitus.
PAS-3B = autoimmune thyroiditis with PA
PAS-3C = autoimmune thyroiditis with vitiligo or alopecia or another organ-specific autoimmune disease
Patients with autoimmune thyroid disease, IMDM and positive adrenal antibodies should be also considering as PAS-3.
The most common PAS-3 combination is autoimmune disease of thyroid gland and pernicious anemia.
The second most common combination is IMDM with some form of autoimmune thyroid disease. 20-30 percent of patients with autoimmune thyroid disease have positive parietal cell antibodies, 30 percent of PA patients have thyroid disease. 20 percent of IMDM patients have thyroid disease.
Incidence: PAS-3 is most frequent among middle-aged women.
Treatment: Depends on which organ is affected. Reatment involves life-long follow up and screening for another glandular failure in patients already diagnosed with PAS-3.
Pathogenesis: PAS-3 is a combination of autoimmune diseases as described above. There are other pieces of evidence that PAS-3 is an autoimmune disease:
- Autoantibody presence in serum
- Monoclonal infiltration of affected organs, later atrophy and fibrosis.
- PAS-3 is often observed in some families in pattern which suggesting autosomal dominant inheritance with incomplete penetrance. No locus association was found so far.
- Association with HLA II type
Mice model for PAS -3 is BioBreeding/Worcester rats (BB/W). In diabetic BBW mice, lymphocytic thyroiditis is also found.