Geographical Distribution, Incidence, Malignancies, and Outcome of 136 Eastern Slavic Patients With Nijmegen Breakage Syndrome and NBN Founder Variant c.657_661del5.

Nijmegen breakage syndrome (NBS) is a DNA repair disorder characterized by combined immunodeficiency and a high predisposition to lymphoid malignancies. The majority of NBS patients are identified with a homozygous five base pair deletion in the Nibrin (NBN) gene (c.657_661del5, p.K219fsX19) with a founder effect observed in Caucasian European populations, especially of Slavic origin. We present here an analysis of a cohort of 136 NBS patients of Eastern Slav origin across Belarus, Ukraine, Russia, and Latvia with a focus on understanding the geographic distribution, incidence of malignancy, and treatment outcomes of this cohort. Our analysis shows that Belarus had the highest prevalence of NBS (2.3 per 1,000,000), followed by Ukraine (1.3 per 1,000,000), and Russia (0.7 per 1,000,000). Of note, the highest concentration of NBS cases was observed in the western regions of Belarus and Ukraine, where NBS prevalence exceeds 20 cases per 1,000,000 people, suggesting the presence of an "Eastern Slavic NBS hot spot." The median age at diagnosis of this cohort ranged from 4 to 5 years, and delay in diagnosis was more pervasive in smaller cities and rural regions. A total of 62 (45%) patients developed malignancies, more commonly in males than females (55.2 vs. 34.2%; p=0.017). In 27 patients, NBS was diagnosed following the onset of malignancies (mean age: 8 years). Malignancies were mostly of lymphoid origin and predominantly non-Hodgkin lymphoma (NHL) (n=42, 68%); 38% of patients had diffuse large B-cell lymphoma. The 20-year overall survival rate of patients with malignancy was 24%. However, females with cancer experienced poorer event-free survival rates than males (16.6% vs. 46.8%, p=0.036). Of 136 NBS patients, 13 underwent hematopoietic stem cell transplantation (HSCT) with an overall survival of 3.5 years following treatment (range: 1 to 14 years). Indications for HSCT included malignancy (n=7) and immunodeficiency (n=6). Overall, 9% of patients in this cohort reached adulthood. Adult survivors reported diminished quality of life with significant physical and cognitive impairments. Our study highlights the need to improve timely diagnosis and clinical management of NBS among Eastern Slavs. Genetic counseling and screening should be offered to individuals with a family history of NBS, especially in hot spot regions.

Significant age and gender-related variations of main lymphocyte subsets in pediatric patients: Latvian data.

Age and gender-related variability of main lymphocyte subsets (T, B and NK cell absolute counts and percentages from Ly; T4, T8 and DN cell absolute counts and percentages from lymphocytes and from T cells; T4:T8 and T:B ratios) was studied in a large cohort of pediatric patients (2 days - 17 years) at yearly intervals. 4128 6-color TBNK tests performed on BD FACSCanto II flow cytometer were assessed; patients with immune deficiencies and tumors were not included. The study revealed significant age and gender-related changes in all subsets. Absolute counts of T, B, T4 cells dropped from neonates to adolescents, decrease of T8 and NK cells was milder; relative count of T cells increased with age and that of B cells decreased; T4:T8 ratio went down and T:B ratio grew. Total T, T4 cells and T4:T8 ratio were significantly higher in girls, while T8, NK and DN cells - in boys; significantly higher relative and absolute B cell counts in boys appeared in adolescence. We compared our results with reference values for healthy children (Tosato et al., 2015), there was a good concordance, except for DN cells. Advantages of using patient cohort instead of healthy children as reference, possibilities for adjusting age and gender-specific reference ranges and potential international data pooling are discussed. This article is protected by copyright. All rights reserved.

Genetic characteristics of eighty-seven patients with the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive immune deficiency disorder characterized by thrombocytopenia, small platelet size, eczema, recurrent infections, and increased risk of autoimmune disorders and malignancies. WAS is caused by mutations in the WASP gene which encodes WASP, a 502-amino acid protein. WASP plays a critical role in actin cytoskeleton organization and signalling, and functions of immune cells. We present here the results of genetic analysis of patients with WAS from eleven Eastern and Central European (ECE) countries and Turkey. Clinical and haematological information of 87 affected males and 48 carrier females from 77 WAS families were collected. The WASP gene was sequenced from genomic DNA of patients with WAS, as well as their family members to identify carriers. In this large cohort, we identified 62 unique mutations including 17 novel sequence variants. The mutations were scattered throughout the WASP gene and included single base pair changes (17 missense and 11 nonsense mutations), 7 small insertions, 18 deletions, and 9 splice site defects. Genetic counselling and prenatal diagnosis were applied in four affected families. This study was part of the J Project aimed at identifying genetic basis of primary immunodeficiency disease in ECE countries. This report provides the first comprehensive overview of the molecular genetic and demographic features of WAS in ECE.