Question

describe what affect genetic mutations inactivating AID will have on the immune system.

Answer 1

AID or commonly known as Activation Induced Cytidine Deaminase is and enzyme that deaminates Cytidine nucleotides into Uracil nucleotides.It is an DNA editing enzyme belonging to the APOBEC family. AID is expressed in B-cells majorly.AID has two functions in B-cells:

1)It gives rise to Somatic Hypermutation in the variable region upon stimulation by antigen thereby giving rise to specificity of the antibody

2)It gives rise to chromosomal translocation in the immunoglubulin region thereby generating class switch recombination

If AID is inactivated it will hamper the two functions stated above,i/e AID cannot deaminate C to U.

No generation of high affinity antibody will occur thereby giving rise to low affinity antibodies which cannot effectively clear the antigens,also no class switching would occur thereby giving rise to only IgM antibodies only,thereby giving rise to Hyper IgM syndrome.In this syndrome individuals are more prone to attack by pathigens due to severe immunodeficiency.

Thus genetic mutation in AID that inactivates it can give rise to the above complications.