What causes severe combined immunodeficiency (SCID)?

Updated: Aug 11, 2020
  • Author: Francisco J Hernandez-Ilizaliturri, MD; Chief Editor: Emmanuel C Besa, MD  more...
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SCID disorders are the result of specific genetic alterations in key regulators of B-cell, T-cell, and/or natural killer (NK)-cell activation, proliferation, or differentiation. The genetic alterations have been identified in the following disorders, which has led to the investigation of gene therapy as an attractive intervention to treat such conditions:

  • XSCID – Genetic defects in the gamma C gene, leading to defects in various cytokine receptors

  • ADA deficiency – Genetic mutations in the ADA enzyme

  • JAK3 deficiency – Defects in the Janus signaling kinase that interacts with the intracellular portion of the common gamma chain of various cytokine receptors

  • RAG1 and RAG2 deficiency – Specific mutations and genetic defects in the RAG1 and RAG2 enzyme

  • Omenn syndrome

  • CHH – Mutations in RMRP, the RNA component of the ribonucleoprotein complex. RNase MRP consists of an RNA molecule bound to several proteins (as described by Ridanpaa et all, it has at least 2 functions: cleavage of RNA in mitochondrial DNA synthesis and nucleolar cleaving of pre-rRNA. [18] This group of investigators recently identified several mutations in RMPR in patients with CHH.)

  • Reticular dysgenesis

  • Wiskott-Aldrich syndrome (WAS) - Rare X-linked disorder with variable clinical phenotypes that correlate with specific mutations in the WAS protein (WASP) gene

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