Unusual Polyclonal IgM in an IgG Deficient Patient with Autoimmune Lymphoproliferative Syndrome: A Case Study and Literature Review.

Autoimmune lymphoproliferative syndrome (ALPS) is a rare genetic disease caused germline mutation of FAS gene, gene encoding Fas ligand or Caspase 10 gene. However, in 20% of all ALPS patients, genetic defect is unknown. We presented a case of a 20-year-old male with a history of autoimmune lymphoproliferative syndrome (ALPS; confirmed by genetic study) who came to our medical center with a concern for malignancy. Although no malignancy was detected, his lack of IgA, very low level of IgG (requiring therapy with intravenous IgG) and highly elevated polyclonal IgM (hyperimmunoglobulin M syndrome) were unusual findings because ALPS patients with hypergammaglobulinemia usually demonstrate elevated IgA or IgG.