Triethylenetetramine (TETA and trien), also known as trientine (INN) when used medically, is an organic compound with the formula [CH2NHCH2CH2NH2]2. The pure freebase is a colorless oily liquid, but, like many amines, older samples assume a yellowish color due to impurities resulting from air-oxidation. It is soluble in polar solvents. The branched isomer tris(2-aminoethyl)amine and piperazine derivatives may also be present in commercial samples of TETA. The hydrochloride salts are used medically as a treatment for copper toxicity. Uses
The reactivity and uses of TETA are similar to those for the related polyamines ethylenediamine and diethylenetriamine. It is primarily used as a crosslinker ("hardener") in epoxy curing. Medical uses
The hydrochloride salt of TETA, referred to as trientine hydrochloride, is a chelating agent that is used to bind and remove copper in the body to treat Wilsons disease, particularly in those who are intolerant to penicillamine. Some recommend trientine as first-line treatment, but experience with penicillamine is more extensive.Trientine hydrochloride (brand name Syprine) was approved for medical use in the United States in November 1985.Trientine tetrahydrochloride (brand name Cuprior) was approved for medical use in the European Union in September 2017. It is indicated for the treatment of Wilsons disease in adults, adolescents and children five years of age or older who are intolerant to D-penicillamine therapy.Trientine dihydrochloride (brand name Cufence) was approved for medical use in the European Union in July 2019.
Autoimmune enteropathy (AIE) is a rare disorder of the immune system that affects infants, young children and (rarely) adults causing severe diarrhea, vomiting, and other morbidities of the digestive tract. AIE causes malabsorption of food, vitamins, and minerals often necessitating replacement fluids and total parenteral nutrition. Some disorders, such as IPEX syndrome, include autoimmune enteropathy as well as autoimmune "pathies" of the skin,  thyroid,  other glands, or kidneys. Symptoms
The main symptoms of AIE include:

Diarrhea (frequent loss of fluids)
Intestinal inflammation
Vomiting
Intestinal bleeding
Difficulty or inability to gain weight
Rapid weight loss
Decreased urine output from dehydration

Diagnosis
There is a diagnostic test for AIE that looks for an antibody against the enterocyte. The diagnostic test contains the Western Blot which can identify the antibody IgG or IgA and with the immunohistochemistry can localize these antibodies. Endoscopy with biopsies of the colon, small colon, stomach, and other locations may be helpful in diagnosing. This test is done to look at the stomach and small intestines and to see what cells are infiltrating the digestive tract. There are also documented cases of autoimmune enteropathy where the auto-antibodies were undetectable and the diagnosis was made on the basis of clinical presentation and response to treatment. Types
There are 3 types of autoimmune enteropathy:Type 1: IPEX syndrome: Immune dysregulation, Polyendocrinopathy, Enteropathy, X – linked 
	syndrome, which is caused by a mutation in the FOXP3 gene. This can only affect boys. Type 2: IPEX-like, which manifests similarly to IPEX syndrome but without recognizable mutations in the FOXP3 gene.