Adenosine deaminase deficiency (ADA deficiency) is a metabolic disorder that causes immunodeficiency. It is caused by mutations in the ADA gene. It accounts for about 10–15% of all cases of autosomal recessive forms of severe combined immunodeficiency (SCID) among non-inbred populations.
How is ADA deficiency treated?
Early diagnosis of ADA-deficient SCID and initiation of treatment is essential in this otherwise fatal condition. Current treatment options include enzyme replacement therapy (ERT), allogeneic haematopoietic stem cell transplant (HSCT), and autologous gene therapy (GT)
What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.MediumAnswer
Gene therapy is the process of introduction of DNA into an organism e.g. human beings in order to treat a disease. It is used to replace a missing gene product or to correct mutant alleles. ADA is an autosomal-recessive inherited disorder that occurs due to defective adenosine deaminase (ADA) enzyme. Please with this enzyme deficiency suffer from severe combined immunodeficiency (SCID) conditions. Human gene therapy trial can be used for ex vivo introduction of functional ADA gene in bone marrow cells of the patient, suffering from SCID. For this process, an engineered retrovirus containing a functional ADA gene is used to transfer the ADA gene into stem cells isolated from the patient with SCID. The treated cells or modified cells with the good ADA gene are reintroduced into the patient’s marrow.
Cystic Fibrosis (CF) is an autosomal recessive genetic disease that affects the lungs. It is characterized by the thick and sticky mucus due to defective gene. It occurs due to mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. It can be treated by gene therapy using DNase. DNase is a DNA-destroying enzyme that breaks DNA strands remained by dying cells. DNase I reduces sputum viscosity in the lungs of CF patients as viscous sputum causes recurrent infections and affects lung function.
