Two international research teams have discovered a novel human gene which is directly involved in a mechanism of regulation of autoimmune response. The gene is solely responsible for a systemic autoimmune disease called APECED. Autoimmune diseases comprise a variety of clinical conditions ranging from rheumatoid arthritis to diabetes. They are known to often have familial background but the genetic factors regulating autoimmune response have so far remained unclear. The new findings are expected to have considerable implications in the understanding of the mechanisms of destructive autoimmune response.
The disease studied by the two groups is
called APECED for autoimmune
polyendocrinopathy-candidiasis-ectodermal dystrophy The
disease is mostly found in certain isolated populations such
as among Finns, Iranian Jews and Sardinians. Clinically,
APECED comprises of a variety of autoimmune manifestations
affecting mainly endocrine organs, such as parathyroid gland,
thyroid gland, adrenal cortex and the gonads. The patients
generate autoantibodies against the affected organs which
consequently become functionless during the course of the
life-long disease.
APECED is known to be an inherited condition and in 1994 the
disease locus was localized to chromosome 21q22.3 by Pr Leena
Peltonen's group from the National Public Health Institute
(Helsinki, Finland). After that publication, Pr Peltonen's
group teamed up with Dr Marie-Laure Yaspo and her group from
Max Planck Institute for Molecular Genetics (Berlin, Germany)
to identify the APECED gene. A second international team led
by Pr Nobuyoshi Shimizu from Keio University (Tokyo, Japan),
Pr Stylianos Antonarakis from University of Geneva and Pr Kai
Krohn from University of Tampere (Finland) also began hunting
for the APECED gene and the race was on.
The race has now ended in a tie, and the
two international teams report the cloning and initial
characterization of the same gene, defective in APECED. The
data are published independently by the two teams in the
December issue of "Nature Genetics".
The function of the gene and its product is still unknown,
but some structural features of the protein coded by the
APECED gene have characteristics of factors capable of
regulating the expression and/or function of other genes.
Whether these other genes that are under control of the
APECED gene product are specifically expressed in the thymus
and in other immunological tissues is still disputable. It is
however likely that the APECED gene and its product are
taking part in a chain of biological events that regulate
immune response.
The APECED gene is the first gene which is solely responsible for regulation of autoimmunity and thus the finding may have vast practical implications. Although APECED as such is not a common disease, the underlying mechanism of this disease may be common to other autoimmune conditions, such as diabetes and rheumatoid arthritis, disease with important clinical as well as socio-economical implications.