HTT and celiac disease: Intestinal dysfunction in APECED can be due to rare conditions like celiac disease, exocrine pancreas insufficiency, intestinal lymphangiectasia, or intestinal infections such as Candida albicans, Giardia lamblia, Clostridium difficile etc. There is also evidence of an autoimmune origin associated with the presence of circulating antibodies against tryptophan hydroxylase (TPHAbs), histidine hydroxylase (HD) or L-amino acid decarboxylase (AADC) Abs [1, 24, 25].