![person studying](/sites/default/files/styles/large/public/understandingpi.jpg?itok=Zo3vrl11)
Constitutional mismatch repair deficiency
Related gene: PMS2
Inheritance pattern: Autosomal recessive
PMS2 gene variants cause a type of constitutional mismatch repair deficiency (CMMRD) with defective Ig class switching from IgM to IgG and IgA. It is a very rare primary immunodeficiency resulting in low serum IgG and IgA with elevated serum IgM. This disorder results in café-au-lait spots on the skin, and patients are predisposed to several types of cancers.