A Boy Aged 5 Years 10 Months with IgM Deficiency and Antibody Deficiency to Streptococcus pneumoniae Associated with TNFRSF13B C104R Heterozygous Mutation

The case is presented of a boy aged 5 years and 10 months with recurrent infections and intermittent thrombocytopenia who had immunoglobulin M (IgM) deficiency and specific antibody deficiency to Streptococcus pneumoniae . Whole exome sequencing was performed and revealed a transmembrane activator and calcium modulator and cyclophilin ligand interactor gene mutation, which has been seen in common variable immunodeficiency. He was treated with IgG antibody replacement therapy and has been free of infection with resolution of his thrombocytopenia.