Categories: Immune system phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 120950 (gene) , 613790 (trait)

Links to relevant human diseases in MONDO:

• MONDO:0013422: type I complement component 8 deficiency

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal

Disease-related: yes

Key variant known: no

Cross-species summary: Complement component 8 consists of three peptides: the alpha, beta and gamma chains, each encoded by a separate locus. The alpha and beta chains are bound covalently through a disulphide link, forming the alpha-gamma subunit, which is non-covalently (i.e. weakly) associated with the beta chain. Disorders resulting from deficiency of the alpha-gamma subunit are called C8 deficiency, or C8 deficiency, type I; disorders resulting from deficiency of the beta chain are called C8 deficiency, type II.

Species-specific symbol: C8D

Species-specific description: C8 deficiency was discovered in a line of rabbits undergoing selection for high and low total complement haemolytic activity (Komatsu, 1985). Both the alpha and gamma genes are transcribed, producing normal quantities of mRNA. However, the mature mRNA from the alpha gene of C8-deficient rabbits includes a 93-bp intron, suggesting that the disorder is due to a mutation at an exon/intron junction (Komatsu, 1992). Sequencing of mutant and normal genes is underway, to determining the exact mutation.

Clinical features: dwarfism (non-pituitary); small litter size; small thymus; low survival rate; severely reduced bactericidal activity; enhanced delayed-type hypersensitivity

Associated gene: