What is Adenosine Deaminase Deficiency?
It is defined as a condition in which there is a metabolic disorder and is autosomal recessive in the nature. It is also known as the ADA deficiency or ADA SCID. It leads to the immune deficiency. It leads to 15 percent of all cases of the severe combined immune deficiency which refers to the SCID. This disorder is present in the infancy and in child hood, adolescence and adult hood. The onset age is related to the severity and multiple genotypes linked with this disorder.
What is the patho physiology of Adenosine Deaminase Deficiency?
It includes the absence of enzyme adenosine deaminase which is encoded by a gene on chromosome number 20. In this the de oxyadenosine gets aggregated which may lead to increase in the S adenosyl homo cysteine as the enzyme adenosine deaminase plays a vital role in the salvage pathway of purine. These substances are toxic to immature lymphocytes which are not able to mature. Its deficiency could build up a nucleotide metabolite in the cell. But this build up is quite significant for B and T cells. It is more important for the T cells and may lead to the under development and formation of small thymus. So, the immune system is very much compromised and may be absent in some cases.
What is the genetics of Adenosine Deaminase Deficiency?
It includes the autosomal recessive nature. It denotes that the defective gene present for this disorder is located on the auto some. The chromosome 20 is an auto some. There is a need of two copies of the defective gene in order to have this disorder. They are inherited one from each parent. The parents of the patient with this disorder carry one copy of the defective gene but they do not experience any signs or symptoms.