In the August 2005 issue of Nature Genetics, two research studies present evidence for a new genetic factor underlying two human immunodeficiency syndromes. Common variable immunodeficiency (CVID), the most prevalent primary immunodeficiency, is characterized by various immune-system abnormalities and defective formation of all antibody types. A related syndrome, IgA deficiency (IgAD), is characterized by selective deficiency in IgA (immunoglobulin A) antibodies. IgA protects against infections of the mucous membranes lining the mouth, airways and digestive tract.
Bodo Grimbacher and colleagues report the identification of a gene defective in several families and unrelated individuals with CVID. In an accompanying study, Raif Geha and colleagues report defects in the same gene in individuals with either CVID or IgAD. The gene, encoding the protein TACI, is involved in switching between antibody types in antibody-producing white blood cells.
CVID and IgAD have common and diverse clinical presentations but are particularly characterized by increased risk of infection and autoimmune disorders. A mixture of genetic and environmental factors is thought to influence risk of developing these syndromes but the underlying genetic causes of CVID are largely unknown. CVID and IgAD are often found in the same families, and so a common genetic basis for these syndromes has long been suspected.
Bodo Grimbacher (University Hospital Freiburg, Germany)
Raif S. Geha (Children's Hospital, Boston, MA, USA)
Also published online: Paper #1; Paper #2.
(C) Nature Genetics press release.
Message posted by: Trevor M. D'Souza