Nijmegen breakage syndrome is a rare NBN-related DNA damage response disorder characterized by chromosomal instability, progressive microcephaly, growth retardation, immunodeficiency, and marked cancer susceptibility. Available mechanistic data support defective DNA repair with delayed p53-mediated DNA damage response and abnormal neurogenesis.
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Conditions with similar clinical presentations that must be differentiated from Nijmegen breakage syndrome:
name: Nijmegen breakage syndrome
creation_date: "2026-04-13T22:47:36Z"
description: >-
Nijmegen breakage syndrome is a rare NBN-related DNA damage response disorder
characterized by chromosomal instability, progressive microcephaly, growth
retardation, immunodeficiency, and marked cancer susceptibility. Available
mechanistic data support defective DNA repair with delayed p53-mediated DNA
damage response and abnormal neurogenesis.
category: Mendelian
parents:
- hereditary disease
- chromosomal instability syndrome
classifications:
harrisons_chapter:
- classification_value: GENETICS_ENVIRONMENT_DISEASE
notes: >-
Monogenic autosomal recessive chromosomal-instability syndrome caused by
biallelic NBN variants.
- classification_value: ONCOLOGY_HEMATOLOGY
notes: >-
Marked cancer susceptibility — lymphoma above all — is a core clinical
domain of the disease (see the Lymphoma phenotype in this entry).
evidence:
- reference: PMID:35748970
reference_title: "Human Inborn Errors of Immunity: 2022 Update on the Classification from the International Union of Immunological Societies Expert Committee."
supports: SUPPORT
evidence_source: OTHER
snippet: "Microcephaly, dysmorphic facies; lymphomas and solid tumors"
explanation: >-
The IUIS 2022 Table 2 row for Nijmegen breakage syndrome lists
lymphomas and solid tumors among its associated features, supporting
the oncologic classification axis.
iuis_category:
classification_value: combined immunodeficiency with syndromic features
notes: >-
IUIS 2022 classification of inborn errors of immunity (Tangye et al.,
PMID:35748970), Table 2 "Combined immunodeficiencies with associated or
syndromic features", section 2 "DNA Repair Defects Other Than Those
Listed in Table 1", row "Nijmegen breakage syndrome" (listed under the
gene symbol NBS1, the older alias of NBN; AR, OMIM 602667).
evidence:
- reference: PMID:35748970
reference_title: "Human Inborn Errors of Immunity: 2022 Update on the Classification from the International Union of Immunological Societies Expert Committee."
supports: SUPPORT
evidence_source: OTHER
snippet: "Nijmegen breakage syndrome NBS1 AR 602667 Progressive decrease; may have low TRECs and T cells by NBS"
explanation: >-
Table 2 section 2 row identifying Nijmegen breakage syndrome (NBS1 =
NBN) among combined immunodeficiencies with associated or syndromic
features; the quote joins the row's wrapped lines in the cached PDF
extraction.
synonyms:
- NBS
disease_term:
preferred_term: Nijmegen breakage syndrome
term:
id: MONDO:0009623
label: Nijmegen breakage syndrome
inheritance:
- name: Autosomal recessive inheritance
description: >-
Nijmegen breakage syndrome is caused by pathogenic biallelic NBN variants
and follows autosomal recessive inheritance.
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Nijmegen Breakage Syndrome (NBS) is a rare autosomal recessive genetic disorder caused by mutations within nibrin (NBN), a DNA damage repair protein."
explanation: This directly supports autosomal recessive inheritance in NBS.
prevalence:
- population: Worldwide
measure_type: UNKNOWN
prevalence_class: NOT_YET_DOCUMENTED
notes: >-
No reliable prevalence estimate exists. The disease occurs worldwide but is
distinctly enriched in Central and Eastern European (Slavic) populations,
where the carrier frequency of the founder allele c.657_661del5
(p.K219fsX19) is estimated at about 1 per 177 newborns.
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Nijmegen breakage syndrome is a rare disease and there are no reliable estimates of its prevalence."
explanation: The review states directly that no reliable prevalence estimate exists.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "c.657_661del5 (p.K219fsX19), estimated to be 1 case per 177 newborns, clearly the result of a founder effect"
explanation: Quantifies the founder-allele carrier frequency behind the Slavic population enrichment.
pathophysiology:
- name: NBN-related DNA repair defect
description: >-
Pathogenic NBN variants impair DNA damage repair, establishing the core
molecular lesion in Nijmegen breakage syndrome.
gene:
preferred_term: NBN
description: Nibrin DNA damage response protein.
modifier: DECREASED
term:
id: hgnc:7652
label: NBN
genes:
- preferred_term: NBN
term:
id: hgnc:7652
label: NBN
biological_processes:
- preferred_term: DNA repair
modifier: ABNORMAL
term:
id: GO:0006281
label: DNA repair
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Nijmegen Breakage Syndrome (NBS) is a rare autosomal recessive genetic disorder caused by mutations within nibrin (NBN), a DNA damage repair protein."
explanation: This directly supports NBN-related DNA repair failure as the primary disease mechanism.
downstream:
- target: Impaired p53-mediated DNA damage response
description: Loss of normal NBN function delays and weakens p53 damage signaling.
- target: Abnormal neurogenesis
description: DNA damage response failure perturbs neurodevelopmental homeostasis.
- target: Chromosomal instability and immune-malignancy susceptibility
description: NBN-dependent DNA repair failure also produces systemic chromosomal instability, immunodeficiency, and lymphoid malignancy susceptibility.
- name: Impaired p53-mediated DNA damage response
description: >-
Patient-derived organoids show delayed p53 signaling after genotoxic stress,
linking NBN dysfunction to defective checkpoint activation.
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "After exposure to bleomycin, NBS organoids undergo delayed p53-mediated DNA damage response"
explanation: This directly supports impaired p53-mediated DNA damage response in NBS.
downstream:
- target: Abnormal neurogenesis
description: Delayed p53 signaling contributes to abnormal neural development.
- name: Abnormal neurogenesis
description: >-
Defective DNA damage signaling contributes to disrupted cerebral organoid
architecture and premature neural differentiation.
biological_processes:
- preferred_term: neurogenesis
modifier: ABNORMAL
term:
id: GO:0022008
label: neurogenesis
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "The organoids exhibit premature differentiation, and Neuronatin (NNAT) over-expression."
explanation: This directly supports abnormal neurogenesis and premature neural differentiation in NBS organoids.
downstream:
- target: Neuronal apoptosis
description: Abnormal neurogenesis progresses to neuronal loss in NBS organoids.
- name: Neuronal apoptosis
description: >-
Delayed DNA-damage signaling and aberrant neuronal differentiation culminate
in neuronal loss.
biological_processes:
- preferred_term: apoptosis
modifier: ABNORMAL
term:
id: GO:0006915
label: apoptotic process
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "After exposure to bleomycin, NBS organoids undergo delayed p53-mediated DNA damage response and aberrant trans-synaptic signaling, which ultimately leads to neuronal apoptosis."
explanation: This directly supports neuronal apoptosis as a downstream consequence of the impaired damage-response state in NBS organoids.
downstream:
- target: Microcephaly
description: Neuronal loss contributes to progressive microcephaly.
- name: Chromosomal instability and immune-malignancy susceptibility
description: >-
NBN-related DNA repair failure produces chromosomal instability with systemic
growth, immune, and lymphoid-malignancy manifestations beyond the
neurodevelopmental branch.
biological_processes:
- preferred_term: DNA repair
modifier: ABNORMAL
term:
id: GO:0006281
label: DNA repair
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Hallmarks of NBS include chromosomal instability and clinical manifestations such as growth retardation, immunodeficiency, and progressive microcephaly."
explanation: This supports chromosomal instability together with growth and immune manifestations in NBS.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This review links NBS to immunodeficiency and lymphoid malignancy susceptibility.
downstream:
- target: Growth delay
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
description: Systemic chromosomal instability and NBS disease biology are associated with growth retardation.
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism."
explanation: This syndrome review supports growth retardation as a principal NBS manifestation.
- target: Immunodeficiency
causal_link_type: DIRECT
description: DNA repair failure and chromosomal instability in NBS are associated with combined cellular and humoral immunodeficiency.
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This review directly supports immunodeficiency as an integral NBS manifestation.
- target: Lymphoma
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- chromosomal instability
- lymphoid malignancy predisposition
description: Genomic instability and immune dysregulation create strong susceptibility to lymphoid malignancy.
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This review supports lymphoid malignancy predisposition in NBS.
phenotypes:
- name: Microcephaly
category: Neurological
diagnostic: true
description: Progressive microcephaly is one of the classic hallmarks of Nijmegen breakage syndrome.
phenotype_term:
preferred_term: Microcephaly
term:
id: HP:0000252
label: Microcephaly
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Hallmarks of NBS include chromosomal instability and clinical manifestations such as growth retardation, immunodeficiency, and progressive microcephaly."
explanation: This directly supports progressive microcephaly as a hallmark NBS phenotype.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism."
explanation: This syndrome review directly supports progressive microcephaly as a defining clinical manifestation of NBS.
- name: Growth delay
category: Growth
diagnostic: true
description: Growth retardation is a major clinical manifestation of Nijmegen breakage syndrome.
phenotype_term:
preferred_term: Growth delay
term:
id: HP:0001510
label: Growth delay
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Hallmarks of NBS include chromosomal instability and clinical manifestations such as growth retardation, immunodeficiency, and progressive microcephaly."
explanation: This directly supports growth retardation in NBS.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism."
explanation: This syndrome review directly supports mild growth retardation as a principal clinical manifestation of NBS.
- name: Immunodeficiency
category: Immunologic
diagnostic: true
description: Immunodeficiency is a core non-neurologic hallmark of Nijmegen breakage syndrome.
phenotype_term:
preferred_term: Immunodeficiency
term:
id: HP:0002721
label: Immunodeficiency
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Hallmarks of NBS include chromosomal instability and clinical manifestations such as growth retardation, immunodeficiency, and progressive microcephaly."
explanation: This directly supports immunodeficiency as a hallmark disease feature.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This syndrome review directly supports immunodeficiency as an integral manifestation of NBS.
- name: Lymphoma
category: Oncologic
description: >-
Nijmegen breakage syndrome confers marked susceptibility to lymphoid
malignancy, which is a major determinant of prognosis: over 40% of
patients develop a malignant disease, predominantly lymphoid, by age 20.
phenotype_term:
preferred_term: Lymphoma
term:
id: HP:0002665
label: Lymphoma
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This directly supports lymphoma susceptibility as a core oncologic manifestation of NBS.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "By the age of 20 years, over 40% of NBS patients develop a malignant disease, predominantly of lymphoid origin."
explanation: Quantifies the age-anchored malignancy risk that dominates NBS prognosis.
- name: Increased sensitivity to ionizing radiation
category: Laboratory
description: >-
Radiosensitivity is an integral clinical manifestation of Nijmegen breakage
syndrome, reflecting defective NBN-mediated DNA double-strand break repair.
phenotype_term:
preferred_term: Increased sensitivity to ionizing radiation
term:
id: HP:0011133
label: Increased sensitivity to ionizing radiation
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This review identifies radiosensitivity as an integral NBS manifestation, directly attributable to defective DNA double-strand break repair by nibrin.
- name: Spontaneous chromosomal breakage with 7;14 rearrangements
category: Laboratory
description: >-
Spontaneous chromosomal breakage in peripheral T lymphocytes, preferentially
involving chromosomes 7 and 14, is the characteristic cytogenetic hallmark
and key laboratory diagnostic finding in Nijmegen breakage syndrome.
phenotype_term:
preferred_term: Chromosome breakage
term:
id: HP:0040012
label: Chromosome breakage
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "spontaneous chromosomal breakage in peripheral T lymphocytes with rearrangements preferentially involving chromosomes 7 and 14"
explanation: This review identifies spontaneous chromosomal breakage with preferential 7;14 rearrangements as the characteristic cytogenetic laboratory finding in NBS.
- name: Hypergonadotropic hypogonadism
category: Endocrine
description: >-
Hypergonadotropic hypogonadism is a principal clinical manifestation of
Nijmegen breakage syndrome in females, reflecting DNA repair-dependent
gonadal dysfunction.
phenotype_term:
preferred_term: Hypergonadotropic hypogonadism
term:
id: HP:0000815
label: Hypergonadotropic hypogonadism
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism."
explanation: This review identifies hypergonadotropic hypogonadism as a principal clinical manifestation of NBS in female patients.
- name: Intellectual disability
category: Neurological
description: >-
Mild-to-moderate intellectual disability is a principal clinical
manifestation of Nijmegen breakage syndrome.
phenotype_term:
preferred_term: Mild-to-moderate intellectual disability
term:
id: HP:0001249
label: Intellectual disability
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism."
explanation: This review lists mild-to-moderate intellectual disability among the principal clinical manifestations of NBS.
- name: Dysmorphic facial features
category: Craniofacial
description: >-
Dysmorphic facial features are a principal clinical manifestation of
Nijmegen breakage syndrome, accompanying the progressive microcephaly.
phenotype_term:
preferred_term: Dysmorphic facial features
term:
id: HP:0001999
label: Abnormal facial shape
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism."
explanation: This review lists dysmorphic facial features among the principal clinical manifestations of NBS.
- name: Recurrent sinopulmonary infections
category: Immunologic
description: >-
Recurrent sinopulmonary infections are the characteristic infectious
consequence of the combined cellular and humoral immunodeficiency of
Nijmegen breakage syndrome.
phenotype_term:
preferred_term: Recurrent sinopulmonary infections
term:
id: HP:0005425
label: Recurrent sinopulmonary infections
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome."
explanation: This review names recurrent sinopulmonary infections as the infectious manifestation of the combined immunodeficiency.
genetic:
- name: NBN
gene_term:
preferred_term: NBN
term:
id: hgnc:7652
label: NBN
association: Causal biallelic hypomorphic variant
notes: >-
Nijmegen breakage syndrome is caused by pathogenic variants in NBN (also
known as NBS1), which encodes the DNA damage response protein nibrin. The
disease alleles are biallelic hypomorphic variants rather than complete
nulls, and a Slavic founder mutation (c.657_661del5) accounts for the
disease being encountered most frequently among Slavic populations.
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Due to a founder mutation in the underlying NBN gene (c.657_661del5) the disease is encountered most frequently among Slavic populations."
explanation: Documents the NBN founder allele and the resulting Slavic population enrichment.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "biallelic hypomorphic mutations in the NBN gene"
explanation: >-
The diagnostic laboratory-findings list specifies biallelic hypomorphic
NBN mutations, supporting the hypomorphic (not complete loss-of-function)
characterization of the disease alleles.
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Nijmegen Breakage Syndrome (NBS) is a rare autosomal recessive genetic disorder caused by mutations within nibrin (NBN), a DNA damage repair protein."
explanation: This directly supports NBN as the causal gene in NBS.
- reference: CGGV:assertion_de6fa1fe-a86e-4f0d-8da8-7690debe9aec-2022-06-21T170000.000Z
reference_title: "NBN / Nijmegen breakage syndrome (Definitive)"
supports: SUPPORT
evidence_source: OTHER
snippet: "NBN | HGNC:7652 | Nijmegen breakage syndrome | MONDO:0009623 | AR | Definitive"
explanation: ClinGen classifies the NBN-Nijmegen breakage syndrome gene-disease relationship as definitive with autosomal recessive inheritance.
treatments:
- name: Hematopoietic stem cell transplantation
description: >-
Hematopoietic stem cell transplantation may be considered in selected
patients with severe immunodeficiency or related complications.
therapeutic_modality: CELL_THERAPY
treatment_term:
preferred_term: hematopoietic stem cell transplantation
term:
id: NCIT:C15431
label: Hematopoietic Cell Transplantation
target_phenotypes:
- preferred_term: Immunodeficiency
term:
id: HP:0002721
label: Immunodeficiency
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "No specific therapy is available for NBS, however, hematopoietic stem cell transplantation may be one option for some patients."
explanation: This review directly identifies HSCT as a treatment option for selected NBS patients.
- name: Genetic counseling and prenatal diagnosis
action_category: COUNSELING_INFORMATIONAL
description: >-
Parents of an affected child should be counselled about the 25% recurrence
risk of this autosomal recessive disorder; prenatal molecular diagnosis is
possible when both familial NBN variants are known.
treatment_term:
preferred_term: genetic counseling
term:
id: NCIT:C15240
label: Genetic Counseling
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Genetic counselling should inform parents of an affected child of the 25% risk for further children to be affected."
explanation: The review states the recurrence-risk counselling content directly.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Prenatal molecular genetic diagnosis is possible if disease-causing mutations in both alleles of the NBN gene are known."
explanation: The review states the precondition for prenatal molecular diagnosis.
diagnosis:
- name: NBN molecular genetic testing
presence: Identification of pathogenic biallelic NBN variants confirms the diagnosis.
description: Molecular testing of NBN is the core confirmatory diagnostic procedure for NBS.
diagnosis_term:
preferred_term: molecular genetic testing
term:
id: NCIT:C19770
label: Molecular Analysis
qualifiers:
- predicate:
preferred_term: has participant
term:
id: RO:0000057
label: has participant
value:
preferred_term: NBN
term:
id: hgnc:7652
label: NBN
evidence:
- reference: DOI:10.3390/cells11050802
reference_title: Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Nijmegen Breakage Syndrome (NBS) is a rare autosomal recessive genetic disorder caused by mutations within nibrin (NBN), a DNA damage repair protein."
explanation: This supports confirmatory diagnosis via NBN molecular testing.
- name: Cytogenetic and functional laboratory testing
presence: >-
Spontaneous 7;14 chromosomal rearrangements, in vitro radiosensitivity,
radioresistant DNA synthesis, and absent full-length nibrin support the
diagnosis.
description: >-
The characteristic laboratory profile combines spontaneous chromosomal
breakage in T lymphocytes, cellular radiosensitivity demonstrable by
cytogenetic methods or colony survival assay, radioresistant DNA synthesis,
and absence of full-length nibrin protein.
diagnosis_term:
preferred_term: cytogenetic and radiosensitivity laboratory analysis
term:
id: NCIT:C18280
label: Cytogenetic Analysis
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "sensitivity to ionizing radiation or radiomimetics as demonstrated in vitro by cytogenetic methods or by colony survival assay"
explanation: The review's laboratory-findings list includes in vitro radiosensitivity testing.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "spontaneous chromosomal breakage in peripheral T lymphocytes with rearrangements preferentially involving chromosomes 7 and 14"
explanation: The review's laboratory-findings list includes the characteristic cytogenetic finding.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "absence of full-length nibrin protein"
explanation: The review's laboratory-findings list includes absent full-length nibrin protein.
differential_diagnoses:
- name: Ataxia-telangiectasia
description: >-
Ataxia-telangiectasia overlaps with Nijmegen breakage syndrome through
chromosomal instability, radiosensitivity, immunodeficiency, and cancer
susceptibility.
distinguishing_features:
- Cerebellar ataxia and telangiectasia favor ataxia-telangiectasia rather than Nijmegen breakage syndrome.
- Progressive microcephaly is characteristic of Nijmegen breakage syndrome and is not a defining feature of ataxia-telangiectasia.
disease_term:
preferred_term: Ataxia-telangiectasia
term:
id: MONDO:0008840
label: ataxia telangiectasia
evidence:
- reference: PMID:41727503
reference_title: "First 2-year experience of nationwide newborn screening for severe forms of T and B cell immunodeficiency: 2.3 million newborns analyzed using TREC and KREC in Russia."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "its use enabled the detection of a substantial proportion of patients with syndromic forms of PID, including Nijmegen breakage syndrome and ataxia-telangiectasia"
explanation: This directly supports diagnostic overlap between Nijmegen breakage syndrome and ataxia-telangiectasia in syndromic immunodeficiency screening, making AT a clinically relevant differential.
- name: Fanconi anemia
description: >-
Fanconi anemia is another chromosomal instability syndrome that can overlap
with Nijmegen breakage syndrome through growth impairment, cancer risk, and
DNA repair defects.
distinguishing_features:
- Bone marrow failure and congenital anomaly patterns favor Fanconi anemia over Nijmegen breakage syndrome.
- Progressive microcephaly with combined immunodeficiency favors Nijmegen breakage syndrome.
disease_term:
preferred_term: Fanconi anemia
term:
id: MONDO:0019391
label: Fanconi anemia
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "In fact, NBS was most commonly confused with Fanconi anaemia and LIG4 syndrome."
explanation: This directly supports Fanconi anemia as a commonly considered differential diagnosis for NBS.
- name: DNA ligase IV deficiency (LIG4 syndrome)
description: >-
LIG4 syndrome shares microcephaly, immunodeficiency, growth retardation,
and radiosensitivity with Nijmegen breakage syndrome and is one of the
disorders NBS is most commonly confused with.
distinguishing_features:
- Molecular testing identifies biallelic LIG4 rather than NBN variants.
disease_term:
preferred_term: LIG4 syndrome
term:
id: MONDO:0011686
label: DNA ligase IV deficiency
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Microcephaly and immunodeficiency are common to DNA ligase IV deficiency (LIG4 syndrome) and severe combined immunodeficiency with microcephaly, growth retardation, and sensitivity to ionizing radiation due to NHEJ1 deficiency (NHEJ1 syndrome)."
explanation: The review identifies the shared microcephaly-immunodeficiency phenotype with LIG4 syndrome.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "In fact, NBS was most commonly confused with Fanconi anaemia and LIG4 syndrome."
explanation: The review states LIG4 syndrome is among the disorders NBS is most commonly confused with.
clinical_burden:
burden_level: HIGH
rationale: >-
Nijmegen breakage syndrome combines progressive microcephaly and
intellectual disability with combined immunodeficiency and an extremely
high malignancy rate that dominates prognosis (over 40% develop malignancy
by age 20, the major cause of death); no specific therapy exists.
evidence:
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "Prognosis is generally poor due to the extremely high rate of malignancies."
explanation: The review's prognosis statement directly supports the high burden rating.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "By the age of 20 years, over 40% of NBS patients develop a malignant disease, predominantly of lymphoid origin."
explanation: Quantifies the malignancy rate underlying the poor prognosis.
- reference: PMID:22373003
reference_title: Nijmegen breakage syndrome (NBS).
supports: SUPPORT
evidence_source: OTHER
snippet: "the major cause of death in these individuals. Of all the chromosomal instability syndromes, the incidence of cancer in NBS patients is one of the highest."
explanation: Identifies malignancy as the major cause of death and ranks NBS cancer incidence among chromosomal instability syndromes.
clinical_trials: []
datasets: []
notes: >-
Asta deep research was completed for this disorder. Final curation relied on
directly reviewed human and patient-derived organoid evidence, which provided
strong support for the core NBN, microcephaly, and DNA-damage-response
mechanisms.
Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.
Record notes
Asta deep research was completed for this disorder. Final curation relied on directly reviewed human and patient-derived organoid evidence, which provided strong support for the core NBN, microcephaly, and DNA-damage-response mechanisms.
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.