Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder, characterized by spontaneous chromosomal instability with predisposition to immunodeficiency and cancer.

We present a repeated NBS in two sons from one woman after two marriages. We describe the clinical data, cytogenetic, and molecular findings of a prenatally diagnosed fetus, and his brothers with NBS. The first patient developed peripheral T-cell lymphoma at the age of 16 years and died 5 months after the protocol start. The diagnosis of NBS was established after his death. The second patient was born after the fifth pregnancy, third delivery in the second marriage; he developed cortical T-cell leukemia at the age of 3 years, received hematopoietic stem cells transplantation (HSCT) and he is alive now. In a year after repeated NBS case in this family, mother became pregnant again and the mutation was detected in the male fetus after the prenatal diagnosis; the pregnancy was aborted. At the age of 41 years, mother’s seventh pregnancy finished by miscarriage. In three months, she was pregnant again, only one mutation in NBN gene was detected during the prenatal diagnostics in the female fetus; healthy female was born at term.

To our knowledge, this is the first time to describe the repeated cases of two patients born with Nijmegen breakage syndrome from one mother and two different fathers. This case highlights the value of checking NBN carrier in Belarusian families during genetic counselling.

中文翻译：

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两个半同胞伴周围T细胞淋巴瘤和皮质T细胞急性淋巴白血病的奈梅亨断裂综合征

奈梅亨破坏综合症（NBS）是一种罕见的常染色体隐性遗传疾病，其特征是自发性染色体不稳定，易患免疫缺陷和癌症。

在两次婚姻后，我们在一名妇女的两个儿子中重复了NBS。我们描述了产前诊断的胎儿及其患有NBS的兄弟的临床数据，细胞遗传学和分子发现。首例患者于16岁时发展为外周性T细胞淋巴瘤，并在方案开始后5个月死亡。NBS的诊断是在他去世后确定的。第二名患者在第五次怀孕后出生，第二次婚姻第三次分娩。他在3岁时患上了皮质T细胞白血病，接受了造血干细胞移植（HSCT），现在还活着。在这个家庭反复发生NBS病例的一年后，母亲再次怀孕，产前诊断后在男性胎儿中发现了这种突变；怀孕流产了。在41岁时，母亲的第七次怀孕因流产而告终。在三个月的时间里，她又怀孕了，在女性胎儿的产前诊断过程中，仅检测到一个NBN基因突变。健康的女性在足月出生。

据我们所知，这是第一次描述来自一位母亲和两位父亲的两名患有奈梅亨破裂综合征的患者的重复病例。该案例强调了在基因咨询过程中检查白俄罗斯家庭中NBN携带者的价值。