Polyglandular Autoimmune Syndrome Type 3 (PAS-3)

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/Treatment

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-3A = autoimmune thyroiditis with immune-mediated diabetes mellitus
  • PAS-3B = autoimmune thyroiditis with PA
  • PAS-3C = autoimmune thyroiditis with vitiligo, alopecia or another organ-specific autoimmune disease


Patients with autoimmune thyroid disease, IMDM and positive adrenal antibodies should also be considered as PAS-3.
The most common PAS-3 combination is autoimmune disease of the 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.

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:

Circumstantial evidence:

  • 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


Indirect Evidence:
Mice model for PAS -3 is BioBreeding/Worcester rats (BB/W). In diabetic BBW mice, lymphocytic thyroiditis is also found.