Antioxidant Defense, Redox Homeostasis, and Oxidative Damage in Children With Ataxia Telangiectasia and Nijmegen Breakage Syndrome.

Ataxia-telangiectasia (AT) and Nijmegen breakage syndrome (NBS) belong to a group of primary immunodeficiency diseases (PI) characterized by premature aging, cerebral degeneration, immunoglobulin deficiency and higher cancer susceptibility. Despite the fact that oxidative stress has been demonstrated in vitro and in animal models of AT and NBS, the involvement of redox homeostasis disorders is still unclear in the in vivo phenotype of AT and NBS patients. Our study is the first to compare both enzymatic and non-enzymatic antioxidants as well as oxidative damage between AT and NBS subjects. Twenty two Caucasian children with AT and twelve patients with NBS were studied. Enzymatic and non-enzymatic antioxidants - glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase-1 (SOD) and uric acid (UA); redox status-total antioxidant capacity (TAC) and ferric reducing ability of plasma (FRAP); and oxidative damage products-8-hydroxy-2'-deoxyguanosine (8-OHdG), advanced glycation end products (AGE), advanced oxidation protein products (AOPP), 4-hydroxynonenal (4-HNE) protein adducts, and 8-isoprostanes (8-isop) were evaluated in serum or plasma samples. We showed that CAT, SOD and UA were significantly increased, while TAC and FRAP levels were statistically lower in the plasma of AT patients compared to controls. In NBS patients, only CAT activity was significantly elevated, while TAC was significantly decreased as compared to healthy children. We also showed higher oxidative damage to DNA (↑8-OHdG), proteins (↑AGE, ↑AOPP), and lipids (↑4-HNE, ↑8-isop) in both AT and NBS patients. Interestingly, we did not demonstrate any significant differences in the antioxidant defense and oxidative damage between AT and NBS patients. However, in AT children, we showed a positive correlation between 8-OHdG and the α-fetoprotein level as well as a negative correlation between 8-OHdG and IgA. In NBS, AGE was positively correlated with IgM and negatively with the IgG level. Summarizing, we demonstrated an imbalance in cellular redox homeostasis and higher oxidative damage in AT and NBS patients. Despite an increase in the activity/concentration of some antioxidants, the total antioxidant capacity is overwhelmed in children with AT and NBS and predisposes them to more considerable oxidative damage. Oxidative stress may play a major role in AT and NBS phenotype.

Circulating T Cells of Patients with Nijmegen Breakage Syndrome Show Signs of Senescence.

PURPOSE: The Nijmegen breakage syndrome (NBS) is an inherited genetic disorder characterized by a typical facial appearance, microcephaly, growth retardation, immunodeficiency, and a strong predisposition to malignancies, especially of lymphoid origin. NBS patients have a mutation in the NBN gene which involves the repair of DNA double-strand breaks (DSBs). Here we studied the peripheral T cell compartment of NBS patients with a focus on immunological senescence. METHODS: The absolute numbers and frequencies of the different T cell subsets were determined in NBS patients from young age till adulthood and compared to age-matched healthy individuals (HI). In addition, we determined the expression of senescent T cell markers and the signal joint T cell receptor excision circles (sjTRECs) content. RESULTS: Our results demonstrate that NBS patients have reduced T cell numbers. NBS patients showed lower numbers of αß+ T cells, but normal γδ+ T cell numbers compared to HI. Concerning the αß+ T cells, both CD4+ as well as CD8+ T cells were excessively reduced in numbers compared to aged-matched HI. In addition, NBS patients showed higher frequencies of the more differentiated T cells expressing the senescent cell marker CD57 and did not express co-stimulatory molecule CD28. These effects were already present in the youngest age group. Furthermore, NBS patients showed lower sjTREC content in their T cells possibly indicative of a lower thymic output. CONCLUSIONS: We conclude that circulating T cells from NBS patients show signs of a senescent phenotype which is already present from young age on and which might explain their T cell immune deficiency.

High prevalence of primary ovarian insufficiency in girls and young women with Nijmegen breakage syndrome: evidence from a longitudinal study.

CONTEXT: Nijmegen breakage syndrome (NBS) is a severe chromosomal instability disorder characterized by microcephaly, growth retardation, immune deficiency, and predisposition for malignancy. It is caused by hypomorphic mutations in the NBN gene, which product belongs to the protein complex critical for processing DNA double-strand breaks during mitotic and meiotic recombination. Data on gonadal function in patients with NBS are limited. OBJECTIVE: Growth and sexual development, along with hormonal assays, were evaluated in girls and young women with NBS homozygous for c.657_661del5 mutation. STUDY DESIGN AND PATIENTS: The group comprised 37 girls and young women with NBS (ages, 0.17-24.25 yr), followed between 1993 and 2008. Patients were divided into three age groups: 1) 1-3 yr; 2) 4-9 yr; and 3) 10 yr and older. Growth, puberty, concentrations of gonadotropins and 17-beta-estradiol, bone age, and pelvic ultrasound were assessed. RESULTS: None of the patients presented a typical growth spurt; the adult height ranged between the 3rd and 25th centiles. Median bone age was delayed by 4.05 yr. Pubarche reached stadium P2 in eight patients and P3 in two patients. In all but one girl, thelarche did not exceed Th2, with low 17beta-estradiol levels. Gonadotropin levels showed a biphasic pattern, with median FSH values of 55.0, 10.9, and 81.9 IU/liter, and LH of 3.2, 0.8, and 21.0 IU/liter in consecutive age groups. Ultrasound visualized small ovaries or solid streaks and the hypoplastic uterus. CONCLUSIONS: Primary ovarian insufficiency and the associated hypergonadotropic hypogonadism are hallmark manifestations in girls and young women with NBS. Our findings emphasize the need for long-term endocrinological and interdisciplinary supervision of these patients.

[Nijmegen Breakage syndrome]. / Nijmegen-Breakage-szindróma.

Nijmegen Breakage syndrome is a rare, autosomal recessive disorder characterized by severe, combined immunodeficiency, recurrent sinopulmonary infections, chromosomal instability, radiosensitivity, predisposition to malignancy, a "bird-like" facial appearance, progressive microcephaly, short stature, and mental retardation. The syndrome is caused by mutations in the NBS1 gene, which encodes a DNA-repair protein, named nibrin. The authors summarize current knowledge on molecular genetics, diagnostic characteristics and therapeutic options of this inborn error of innate immunity.

Nijmegen breakage syndrome: Long-term monitoring of viral and immunological biomarkers in peripheral blood before development of malignancy.

Selected viruses and immune parameters were monitored in 57 patients with Nijmegen breakage syndrome as a proposed tool for early detection of changes preceding development of malignancy. The following parameters were analysed: (1) viral infections; (2) monoclonal proteins; and (3) B-cell and T-cell receptor gene rearrangements in peripheral blood lymphocytes. Viral infections were detected in 68.4% of patients with a predominance of EBV (63.2%), followed by HBV (19.2%) and HCV (8.8%). Monoclonal gammopathy detected in 38.6% of cases correlated with the presence of EBV DNA (p=0.002) and HCV RNA (p=0.04). Clonal Ig and/or TCR gene rearrangements occurred in 73.9% of patients. The presence of at least one of the studied parameters preceded the development of malignancy in 22 patients. Systematic PCR analysis for viral infections and Ig/TCR gene rearrangements, supplemented by detection of monoclonal proteins, is advantageous in monitoring NBS patients before severe complications of the disease, including cancer, appear.