Autoantibodies linked to autoimmune polyendocrine syndrome type I are prevalent in Down syndrome.
BACKGROUND
Patients with Down syndrome are prone to autoimmune diseases which also occur in the recessive disease autoimmune polyendocrine syndrome type I (APS I). Since this disease is caused by mutations in the gene AIRE on chromosome 21, one might speculate that altered expression of AIRE contributes to autoimmune disease in Down syndrome.


OBJECTIVE
To study the prevalence of 11 well-defined autoantibodies, five of which are specific for APS I, associated with various manifestations of APS I in patients with Down syndrome.


METHODS
Sera from 48 patients with Down syndrome were analysed. Autoantibodies against 21-hydroxylase, 17alpha-hydroxylase, side-chain cleavage enzyme, aromatic L-amino acid decarboxylase, cytochrome P4501A2, tyrosine hydroxylase, tryptophan hydroxylase, glutamic acid decarboxylase 65, tyrosine phosphatase IA-2 and transglutaminase were analysed using an immunoprecipitation assay, and thyroid peroxidase autoantibodies were measured using a haemagglutination assay.


RESULTS
Seven of 48 patients had elevated titres of autoantibodies: one against 21-hydroxylase, three against aromatic L-amino acid decarboxylase, one against cytochrome P4501A2, one against glutamic acid decarboxylase 65 and one against tyrosine phosphatase IA-2. None of the patients had clinical or laboratory signs of disease coupled to the respective autoantibody.


CONCLUSIONS
Four patients with Down syndrome had autoantibodies hitherto regarded as unique for APS I, which may suggest a dysregulation of AIRE.
Söderbergh
Annika
A
Department of Medical Sciences, Uppsala University Hospital, Uppsala, Sweden.
Gustafsson
Jan
J
Ekwall
Olov
O
Hallgren
Asa
A
Nilsson
Tomas
T
Kämpe
Olle
O
Rorsman
Fredrik
F
Annerén
Göran
G
D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000097:blood* / Q000145:classification / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000150:complications* / Q000235:genetics / Q000276:immunology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016884:Polyendocrinopathies, Autoimmune / Q000150:complications* / Q000235:genetics / Q000276:immunology
D001323:Autoantibodies