Any hyper-IgM syndrome in which the cause of the disease is a mutation in the UNG gene. The disease is hyper-IgM syndrome type 5 (Monarch Disease Ontology entry MONDO_0011971). Also known as: HIGM5, UNG hyper-IgM syndrome, hyper-IgM syndrome 5, hyper-IgM syndrome caused by mutation in UNG, hyper-IgM syndrome due to UNG deficiency, hyper-IgM syndrome due to uracil N-glycosylase, immunodeficiency with hyper IgM, type 5.