Any Mendelian disease in which the cause of the disease is a mutation in the TRAF3 gene. TRAF3 haploinsufficiency caused by heterozygous loss of function (null) variants presents as an immune dysregulation syndrome of recurrent bacterial infections, autoimmunity, systemic inflammation, B cell lymphoproliferation, and hypergammaglobulinemia. [ https://clinicalgenome.org/affiliation/40080/ http://www.ncbi.nlm.nih.gov/pubmed/35960817 ]