Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024312 (lymphopenia)
 4,859 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Circulating levels of T-cell subsets and NK cells were determined in 78 patients with primary immunodeficiencies, 35 children with recurrent respiratory infections, and healthy age-matched controls. Normal T cell and natural killer (NK) cell values were observed in individuals with immunoglobulin A (IgA) deficiency and X-linked agammaglobulinemia, while reduced OKT4/OKT8 cell ratios and low levels of 5/9+ T helper cells were found in approximately 60% of patients with common variable immunodeficiency. Infants with severe combined immunodeficiency (SCID) and lymphopenia had virtually no cells expressing T-cell or NK-cell surface antigens, but had normal numbers of monocytes and other types of blood cells. Infants with DiGeorge syndrome, other primary T-cell defects, or SCID with B cells had few or no circulating cells of mature T helper-suppressor phenotypes, but had normal numbers of NK cells (HNK-1+) and NK function. These results support the idea of a common stem cell precursor for T, B, and NK cells, each of which follows a separate pathway of differentiation. Profound alterations were observed in the distribution and function of T-cell subsets in ataxia-telangiectasia patients who were previously shown to have thymic dysplasia. A significant reduction in the frequencies of OKT3+ and OKT4+ cells was observed in children with frequent respiratory infections during infancy.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Usefulness of monoclonal antibodies in the diagnosis and monitoring of patients with primary immunodeficiencies: combined experience in three clinical immunology centers. 638 70

The ATM (ataxia-telangiectasia mutated) protein kinase mediates early cellular responses to DNA double-strand breaks (DSBs) generated during metabolic processes or by DNA-damaging agents. ATM deficiency leads to ataxia-telangiectasia, a disease marked by lymphopenia, genomic instability and an increased predisposition to lymphoid malignancies with chromosomal translocations involving lymphocyte antigen receptor loci. ATM activates cell-cycle checkpoints and can induce apoptosis in response to DNA DSBs. However, defects in these pathways of the DNA damage response cannot fully account for the phenotypes of ATM deficiency. Here, we show that ATM also functions directly in the repair of chromosomal DNA DSBs by maintaining DNA ends in repair complexes generated during lymphocyte antigen receptor gene assembly. When coupled with the cell-cycle checkpoint and pro-apoptotic activities of ATM, these findings provide a molecular explanation for the increase in lymphoid tumours with translocations involving antigen receptor loci associated with ataxia-telangiectasia.
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PMID:ATM stabilizes DNA double-strand-break complexes during V(D)J recombination. 1679 70

Ataxia-telangiectasia is a rare autosomal recessive disorder characterized by progressive cerebellar ataxia, oculocutaneous telangiectasias, and variable degrees of immunodeficiency. Immunologic evaluations of affected patients often reveal anomalies of humoral and cell-mediated immunity. We describe a case of ataxia-telangiectasia with an atypical immunodeficiency and a novel mutation in the ATM gene. The patient presented at age 3 years with a perineal cellulitis associated with profound neutropenia and T-cell lymphopenia. Serum immunoglobulin levels and antibody titers were normal. Neurologic evaluation revealed minimal hypotonia and wide-based gait, without other signs of cerebellar dysfunction. The alpha-fetoprotein level was elevated, and molecular genetic testing confirmed the diagnosis of ataxia-telangiectasia, uncovering a novel ATM gene mutation c.3931C>T (p.Gln1311X) in exon 28. This patient presents a unique immunologic pattern with normal immunoglobulin levels, significant lymphopenia, and profound neutropenia. The diagnosis of ataxia-telangiectasia should be considered in children presenting with gait disorder and immunologic defects, regardless of subtype and severity.
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PMID:Ataxia-telangiectasia presenting with a novel immunodeficiency. 2252 Mar 55

There is a need for neonatal screening tools to improve the long-term clinical outcome of patients with primary immunodeficiency diseases (PID). Recently, a PCR-based screening method for both TRECs and KRECs using Guthrie card samples has been developed. However, the applicability of these excision circle assays is limited to patients with severe T or B cell lymphopenia (SCID, XLA and A-T), whereas the most common forms of PID are not detected. Absence of serum IgA is seen in a major fraction of patients with immunological defects. As serum IgA in newborns is considered to be of fetal origin, eluates from routinely collected dried blood spot samples might thus be suitable for identification of children with PID. To assess the applicability of such screening assays, stored Guthrie card samples were obtained from 47 patients with various forms of primary immunodeficiency diseases (SCID, XLA, A-T, HIGM and IgAD), 20 individuals with normal serum IgA levels born to IgA-deficient mothers and 51 matched healthy newborns. Surprisingly, normal serum IgA levels were found in all SCID, XLA, A-T and HIGM patients and, additionally, in all those IgAD patients born to IgA-sufficient mothers. Conversely, no serum IgA was found in any of the 16 IgAD patients born by IgA-deficient mothers. Moreover, half of the IgA-sufficient individuals born by IgA-deficient mothers also lacked IgA at birth whereas no IgA-deficient individuals were found among the controls. IgA in neonatal dried blood samples thus appears to be of both maternal and fetal origin and precludes its use as a reliable marker for neonatal screening of primary immunodeficiency diseases.
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PMID:Placental transfer of maternally-derived IgA precludes the use of guthrie card eluates as a screening tool for primary immunodeficiency diseases. 2291 57