X-Linked Severe Combined Immunodeficiency
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What is X-linked severe combined immunodeficiency?X-linked severe combined immunodeficiency (SCID) is an inherited disorder of the immune system that occurs almost exclusively in males. Boys with X-linked SCID are prone to recurrent and persistent infections caused by certain bacteria, viruses, and fungi. These infections can be very serious or life-threatening. The organisms that cause infection in people with X-linked SCID are described as opportunistic because they ordinarily do not cause illness in healthy people. Many infants with X-linked SCID experience chronic diarrhea and skin rashes, and grow more slowly than other children. Without treatment, affected males usually do not live beyond infancy. How common is X-linked severe combined immunodeficiency?X-linked SCID is the most common form of severe combined immunodeficiency. The exact incidence is unknown, but the condition probably affects at least 1 in 50,000 to 100,000 births. What genes are related to X-linked severe combined immunodeficiency?Mutations in the IL2RG gene cause X-linked severe combined immunodeficiency. The IL2RG gene provides instructions for making a protein that is essential to immune system function. This protein is necessary for the growth and maturation of developing immune system cells called lymphocytes. Lymphocytes defend the body against potentially harmful invaders, make antibodies, and help regulate the entire immune system. Mutations in the IL2RG gene prevent these cells from developing and functioning normally. Without functional lymphocytes, the body is unable to fight off infections. How do people inherit X-linked severe combined immunodeficiency?This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation must be present in both copies of the gene to cause the disorder; this situation occurs only rarely. Therefore, males are affected by X-linked recessive disorders much more frequently than females.
Source: National Institutes of Health
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Research from Indiana University, Department of Medicine in the area of severe combined immunodeficiency described
2007 APR 9 -- A new study, "Epstein-Barr-associated leiomyomatosis and T-cell chimerism after haploidentical bone marrow transplantation for severe combined immunodeficiency disease," is now available. "The clinical course of Epstein-Barr virus (EBV)-associated smooth muscle tumors is variable and there are no reports in patients with mixed T-cell chimerism after bone marrow transplantation (BMT). OBSERVATIONS: A child with X-linked severe combined immunodeficiency disease developed multiple renal and pulmonary leiomyomata 8 years after haploidentical BMT," investigators in the United States report. "Epstein-Barr viral DNA was detectable in the blood and in situ hybridization for EBV-encoded RNAs was positive in the tumor. The tumors have been radiographically stable, chimerism remains mixed, and plasma EBV DNA has been repeatedly negative for over 2 years after donor lymphocyte infusion," wrote S. Atluri and colleagues, Indiana University, Department of Medicine. The researchers concluded: "EBV-associated smooth muscle tumors may occur in patients who are partially reconstituted after BMT for severe combined immunodeficiency and may not require surgery or chemotherapy." Atluri and colleagues published their study in the Journal of Pediatric Hematology (Epstein-Barr-associated leiomyomatosis and T-cell chimerism after haploidentical bone marrow transplantation for severe combined immunodeficiency disease. Journal of Pediatric Hematology, 2007;29(3):166-72). For additional information, contact S. Atluri, Indiana University School of Medicine, Dept. of Medicine, Indianapolis, IN 46202 USA. The publisher of the Journal of Pediatric Hematology can be contacted at: Lippincott Williams & Wilkins, 530 Walnut St., Philadelphia, PA 19106-3621, USA. Keywords: United States, Indianapolis, Bone Marrow, Deficiency Disease, Gynecology, Immunology, Leiomyoma, Pediatric Hematology, Severe Combined Immunodeficiency. This article was prepared by Hematology Week editors from staff and other reports. Copyright 2007, Hematology Week via NewsRx.com.
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