Related gene: LCK
Inheritance pattern: Autosomal recessive
Autosomal recessive disorder due to deficiency of lymphocyte-specific protein-tyrosine kinase (Lck or p56lck), one of the proteins that are activated upon engagement of the TCR/CD3 complex. Depending on the mutation, individuals may present within the first year of life with variable features. While some have a severe combined immunodeficiency (SCID) phenotype, others presented with common variable immune deficiency (CVID) or idiopathic CD4 lymphopenia. Clinical features include failure to thrive, oral candidiasis, sepsis, diarrhea, and hypogammaglobulinemia, combined immunodeficiency, recurrent sinopulmonary infections, and inflammatory/autoimmune manifestations even without immune deficiency. Treatment is supportive with the administration of antibiotics and immunoglobulin (Ig) replacement therapy. Indication to treat with hematopoietic stem cell transplantation (HSCT) is still controversial.