ImmunoDeficiency Resource (IDR)

The clinical syndrome is rare and is due to impaired immunity against mycobacteria. Parental consanguinity and familial forms are frequent and the syndrome is often described as Mendelian susceptibility to mycobacterial infection. In most cases the inheritance is autosomal recessive, but also autosomal dominant and X-linked inheritence have been found. Three molecular forms of IFNγ-receptor deficiency have been described. Complete deficiency of IFNγ1-receptor is associated with severe and often fatal mycobacterial infection, mostly at an early age. These mutations preclude cell surface expression of the receptor or prevent cellular responses to IFNγ, and the type of mutation accounts for clinical heterogeneity. Two forms of partial deficiency in IFNγ1-receptor have been identifiend, associated with milder clinical infections. The more common form of partial deficency in IFNγ1-receptor is due to heterozygous frameshift deletions at exon 6 of the gene, which result in abnormal receptors that accumulates at high levels at the cell surface, exerting a dominativ negative effect. One form of partial IFNγ1-receptor deficiency has been described in two siblings. They expressed the receptor at the cell surface, reduced but did not completely abrogate IFNγ binding, signalling or both.