Mendelian Susceptibility To Mycobacterial Diseases Due To Partial Stat1 Deficiency

Mendelian susceptibility to mycobacterial diseases (MSMD) due to partial STAT1 (signal transducer and activator of transcription 1) deficiency is a genetic variant of MSMD (see this term) characterized by a partial defect in the interferon (IFN)-gamma pathway, leading to mild mycobacterial infections.

Epidemiology

The prevalence is unknown. In 2001, two patients from unrelated kindreds were described and they suffered only mild MSMD. Since 2001, up to six other kindreds have been described to have a partial dominant STAT1 deficiency associated with MSMD.

Clinical description

First infections occur after the age of 3, most commonly with weakly virulent Mycobacterium bovis BCG and Mycobacterium avium complex or with the more virulent Mycobacterium tuberculosis. Clinical penetrance is incomplete and some patients are asymptomatic while others have very mild clinical manifestations. None of the patients identified to date developed severe viral illness.

Etiology

MSMD due to partial STAT1 deficiency is due to heterozygous mutations in the STAT1 gene on chromosome 2q32.2-q32.3 encoding the signal transducer and activator of transcription 1. Two distinct forms have been described: one affecting phosphorylation and the other impairing DNA-binding activity.

Genetic counseling

Transmission is autosomal dominant and genetic counseling is possible.