<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A rare, inherited disease that is marked by a lack of B lymphocytes (white blood cells that make antibodies and help fight infections) and a lack of T lymphocytes (white blood cells that attack virus-infected cells, foreign cells, and cancer cells). Patients with this disease have a high risk of developing viral, bacterial, and fungal infections.</n0:def-definition><n0:def-source>NCI-GLOSS</n0:def-source></n0:ComplexDefinition><n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. It is inherited as an X-linked or autosomal recessive defect. About half of the patients with autosomal recessive SCID are deficient in the enzyme adenosine deaminase.</n0:def-definition><n0:def-source>MSH2003_2003_05_12</n0:def-source></n0:ComplexDefinition>
<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>X-linked or autosomal recessive disorder characterized by defects of both humoral and cell mediated immunity, resulting in low or absent antibody levels, leukopenia, marked susceptibility to infections, and early death.--2004</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>