Hyper IgM, Immunodeficiency with hyper IgM type 5 (hyper-IgM Immunodeficiency With, type 5) - Gen UNG.

Immunodeficiency with hyper IgM type 5 (HIGM5) is a rare disorder characterized by normal or elevated levels of serum IgM with absence of IgG, IgA and IgE, which results in a profound susceptibility to bacterial infections.

This process is due to mutations in the UNG gene, located on the long arm of chromosome 12 (12q23-q24.1). This gene, uracil DNA glycosylase encoding. The UNG enzyme is expressed in B cells This enzyme plays a crucial role in processes of immunoglobulin class switching and somatic hypermutation. An important function uracil DNA glycosylase is of preventing mutagenesis by removing uracil from DNA molecules by cleavage of the N-glycosyl and initiating repair pathway base excision (BER). Uracil bases are produced from cytosine deamination or misincorporation of dUMP residues by DNA polymerase. This gene leads to two different isoforms: ung1 mitochondrial and nuclear UNG2.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests performed in IVAMI: in IVAMI perform detection of mutations associated with immunodeficiency with hyper IgM type 5, by complete PCR amplification of the exons of the UNG gene and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).