Autoimmune polyendocrine syndrome

Infobox_Disease
Name = Autoimmune polyendocrine syndrome


Caption =
DiseasesDB = 29212
DiseasesDB_mult = DiseasesDB2|29690 | ICD10 = ICD10|E|31|0|e|20
ICD9 = ICD9|258.1
ICDO =
OMIM = 240300
OMIM_mult = OMIM2|269200
MedlinePlus =
eMedicineSubj = med
eMedicineTopic = 1867
eMedicine_mult = eMedicine2|med|1868 | MeshID =
In medicine, autoimmune polyendocrine syndromes are a heterogeneous group [cite journal |author=Eisenbarth GS, Gottlieb PA |title=Autoimmune polyendocrine syndromes |journal=N. Engl. J. Med. |volume=350 |issue=20 |pages=2068–79 |year=2004 |pmid=15141045 |doi=10.1056/NEJMra030158 |url=] of rare diseases characterised by autoimmune activity against more than one endocrine organs, although non-endocrine organs can be affected.

There are three "autoimmune polyendocrine syndromes", and a number of other diseases which have endocrine autoimmunity as one of their features.

The syndromes

Type 1

"Autoimmune polyendocrine syndrome, type 1" is also known as the candidiasis-hypoparathyroidism-Addison's disease-syndrome after its main features:
* A mild immune deficiency, leading to persistent mucosal and cutaneous infections with candida yeasts. There is also decreased function of the spleen (asplenism).
* Autoimmune dysfunction of the parathyroid gland (leading to hypocalcemia) and the adrenal gland (Addison's disease: hypoglycemia, hypotension and severe reactions in disease).
* Other disease associations are:
** hypothyroidism
** hypogonadism and infertility
** vitiligo (depigmentation of the skin)
** alopecia (baldness)
** malabsorption
** pernicious anemia
** chronic active (autoimmune) hepatitis

As opposed to type 2, this syndrome inherits in an autosomal recessive fashion and is due to a defect in "AIRE" ("a"uto"i"mmune "re"gulator"),cite journal |author=Bensing S, Fetissov SO, Mulder J, "et al" |title=Pituitary autoantibodies in autoimmune polyendocrine syndrome type 1 |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=104 |issue=3 |pages=949–54 |year=2007 |month=January |pmid=17215373 |pmc=1783420 |doi=10.1073/pnas.0610070104 |url= |accessdate=2008-07-25] a gene located on the 21st chromosome. Normal function of "AIRE", a transcription factor, appears to be to confer immune tolerance for antigens from endocrine organs.

A EU-funded consortium is currently doing translational research on this condition and has established a webpage at [http://www.apeced.net EurAPS] .

Type 2

"Autoimmune polyendocrine syndrome, type 2" (also known as "Schmidt's syndrome"cite journal |author=Heuss D, Engelhardt A, Göbel H, Neundörfer B |title=Myopathological findings in interstitial myositis in type II polyendocrine autoimmune syndrome (Schmidt's syndrome) |journal=Neurol. Res. |volume=17 |issue=3 |pages=233–7 |year=1995 |month=June |pmid=7643982 |doi= |url= |accessdate=2008-07-25] ) is more heterogeneous, occurs more often and has not been linked to one gene. Rather, patients are at a higher risk when they carry a particular HLA genotype (DQ2, DQ8 and DRB1*0404).

Features of this syndrome are:
* Addison's diseasecite journal |author=Betterle C, Zanchetta R |title=Update on autoimmune polyendocrine syndromes (APS) |journal=Acta Biomed |volume=74 |issue=1 |pages=9–33 |year=2003 |month=April |pmid=12817789 |doi= |url= |accessdate=2008-07-25]
* hypothyroidism
* diabetes mellitus (type 1)
* less common associations:
** hypogonadism
** vitiligo

Some researchers favour splitting this syndrome into three distinct syndromes (numbering 2, 3cite journal |author=de Carmo Silva R, Kater CE, Dib SA, "et al" |title=Autoantibodies against recombinant human steroidogenic enzymes 21-hydroxylase, side-chain cleavage and 17alpha-hydroxylase in Addison's disease and autoimmune polyendocrine syndrome type III |journal=Eur. J. Endocrinol. |volume=142 |issue=2 |pages=187–94 |year=2000 |month=February |pmid=10664529 |doi= |url=http://eje-online.org/cgi/pmidlookup?view=long&pmid=10664529 |accessdate=2008-07-25] and 4), but research evidence for these distinct combinations is not convincing.

XPID

The most serious but rarest form is the "X-linked polyendocrinopathy, immunodeficiency and diarrhea"-syndrome, also called IPEX.. This is due to mutation of the "FOXP3" gene on the X chromosome.cite journal |author=Yong PL, Russo P, Sullivan KE |title=Use of Sirolimus in IPEX and IPEX-Like Children |journal=J. Clin. Immunol. |volume= |issue= |pages= |year=2008 |month=May |pmid=18481161 |doi=10.1007/s10875-008-9196-1 |url=http://dx.doi.org/10.1007/s10875-008-9196-1] Most patients develop diabetes and diarrhea as neonates and many die due to autoimmune activity against many organs. Boys are affected, while girls are carriers and might suffer mild disease.

Other diseases

Other diseases featuring polyendocrine autoimmunity:
* Chromosomal abnormalities (Down's syndrome) increase the risk of endocrine autoimmunity
* POEMS syndrome - the "E" is for endocrinopathy; the cause is a paraprotein excreted by a plasmacytoma or multiple myeloma; other features are polyneuropathy, organomegaly (hepatomegaly and splenomegaly), M-protein (paraprotein) and skin changes.
* Several very rare diseases.

Management

In principle, the component diseases are managed as usual. The challenge is to detect the possibility of any of the above syndromes, and to anticipate other manifestations. For example, in a patient with known Type 2 autoimmune polyendocrine syndrome but no features of Addison's disease, regular screening for antibodies against 21-hydroxylase (a feature of Addison's) may prompt early intervention and hydrocortisone replacement to prevent characteristic crises.

References