A Gene Mutation c.2395G>A Leads to TYK2 Deficiency: A Case Report and Literature Review.

Tyrosine kinase 2 () deficiency was formerly defined in patients suffering from autosomal recessive hyperimmunoglobulin E syndrome (AR-HIES). In recent years, it was proposed that human deficiency is probably not a common cause of the AR-HIES but a distinctive illness object. In the current work, a recessive deficiency is reported in a patient suffering from BCG disease and recurrent respiratory infection. It was implied that this patient carried novel missense homozygous mutation (c.2395G>A, p. G799R) in the . Both the and experiments indicated the inhibition effects of the c.2395G>A homozygous mutation on the gene and protein expression. By literature review, we summarized the clinical manifestations, gene mutations, and related cytokine responses of formerly reported patients possessing deficiency. The core manifestation of these patients is infected by intracellular pathogens, such as mycobacteria and/or viruses. Therefore, the possibility of deficiency should be considered when a patient has repeated intracellular bacteria (including tuberculosis bacillus infection), repeated viral infection or eczema.