Severe Combined Immunodeficiency Due To Adenosine Deaminase Deficiency

Watchlist

(log in to enable)

Retrieved

2021-01-23

Source

Orphanet

Trials

—

Genes

ADA, ADA2, CD34, TLR2, DPP4, IL2RG, PNP, NT5C2, RAG1, PAEP, ITPA, JAK3, ADCP1, CECR, ADSL, ADK, DCLRE1C

Drugs

Allogeneic multi-virus specific T lymphocytes targeting BK virus, cytomegalovirus, human herpesvirus-6, Epstein Barr virus and adenovirus, Autologous CD34+ cells transduced with a lentiviral vector containing the human ADA gene ( STRIMVELIS ), Autologous CD34+ cells transfected with retroviral vector containing adenosine deaminase gene, Autologous bone marrow CD34+ cells transduced ex vivo with a self activating HIV-1 -based lentiviral vector, EFS-ADA, Pegademase bovine ( ADAGEN ), haematopoietic stem cells and blood progenitors umbilical cord-derived expanded with (1R, 4R)-N1-(2-benzyl-7-(2-methyl-2H-tetrazol-5-yl)-9H-pyrimido[4,5-b]indol-4-yl)cyclohexane-1,4-diamine dihydrobromide dihydrate

Interested in hearing about new therapies?

Severe combined immunodeficiency (SCID) due to adenosine deaminase (ADA) deficiency is a form of SCID characterized by profound lymphopenia and very low immunoglobulin levels of all isotypes resulting in severe and recurrent opportunistic infections.

Epidemiology

SCID due to ADA deficiency accounts for 10-15% of all cases of SCID. Its annual incidence is estimated to be between 1/200,000 and 1/1,000,000 live births. Both males and females are affected.

Clinical description

SCID due to ADA deficiency has a variable clinical presentation. The most common form presents in infancy with severe and recurrent opportunistic infections (including respiratory tract infections and candidiasis), failure to thrive, and usually results in early death. Ten to 15% of patients have a delayed clinical onset by age 6-24 months, and a smaller percentage have a partial form of ADA deficiency with later onset between ages 4 years and adulthood, both types showing less severe infections and gradual immunologic deterioration. Patients may also present with extraimmune manifestations (including neurodevelopmental deficits, behavioral disorders, sensorineural deafness, and skeletal and hepatic abnormalities) as a result of the systemic nature of ADA expression.

Etiology

SCID due to ADA deficiency is caused by mutations in the ADA gene (20q13.11). The extraimmune manifestations are caused by toxic levels of purine metabolites that result from the deficiency of ADA.

Diagnostic methods

Diagnosis is based on evidence of low or undetectable ADA activity in erythrocytes in combination with evidence of a marked reduction of T, B and NK cell counts when compared to age-matched healthy controls. Diagnosis can be confirmed by raised levels of dATP and reduced S-adenosyl homocysteine hydrolase (SAHH) activity in red cells and elevated amounts of deoxyadenosine in urine.

Differential diagnosis

Differential diagnosis includes all forms of SCID.

Antenatal diagnosis

Prenatal diagnosis can be carried out through mutation analysis or measurement of enzyme activity in trophoblasts cultured from chorionic villus sampling or in cultured amniocytes.

Genetic counseling

Transmission is autosomal recessive.

Management and treatment

Treatment is based on allogenic hematopoietic stem cell transplantation (HSCT), enzyme replacement therapy with pegylated adenosine deaminase enzyme or gene therapy by infusion of CD34+ marrow cells that have been transduced with an ADA-containing vector.

Prognosis

Prognosis depends on the severity of the disease. Without treatment, SCID due to ADA deficiency that presents in infancy usually results in early death. Survival rates after allogenic hematopoietic stem cell transplantation or gene therapy are high.