BLM germline biallelic pathogenic variants cause Bloom syndrome — autosomal-recessive dis...
Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.
| ID | BMA-BLM-GERMLINE-BLOOM-BROAD |
|---|---|
| Type | Actionability |
| Status | reviewed 2026-05-18 | pending_clinical_signoff | actionability review required |
| Diseases | DIS-CRC |
| Sources | SRC-NCCN-PEDIATRIC-SARCOMA |
Actionability Facts
| Biomarker | BIO-BLM-GERMLINE |
|---|---|
| Variant | BLM germline biallelic pathogenic (Bloom syndrome — broad cancer susceptibility) |
| Disease | DIS-CRC |
| ESCAT tier | IIA |
| Recommended combinations | strict UVA/UVB sun protection from infancy (SPF 50+ + protective clothing + UV-blocking eyewear), annual dermatology with comprehensive skin exam (BCC, SCC, melanoma), CBC q3-6mo (leukemia surveillance — AML, ALL, MDS), colonoscopy q1-2y from age 12-15 with polypectomy, EGD q1-2y from age 12-15, breast MRI + mammography annual from age 18-20 (women), low-threshold symptom-directed imaging — atypical cancer presentations at all ages, partner-carrier screening for couples planning children (autosomal-recessive) |
| Contraindicated monotherapy | elective ionizing radiation exposure (diagnostic CT when alternatives available, EBRT for solid tumors when alternatives available) — documented radiosensitivity in Bloom syndrome |
| Evidence summary | BLM germline biallelic pathogenic variants cause Bloom syndrome — autosomal-recessive disorder of replication-fork resolution (BLM RecQ helicase loss). Phenotype: severe pre- and postnatal growth restriction, characteristic facial features + sun-sensitive erythematous facial rash (telangiectatic), immunodeficiency, diabetes, and very high lifetime cancer risk with broad spectrum: leukemia (AML, ALL), lymphoma, early colorectal + gastric + skin (BCC, SCC, melanoma) + breast + GU cancers. Median age at first cancer diagnosis ~25 years; many patients develop multiple primary cancers. Confirmed-carrier (biallelic) surveillance protocol (per Bloom Syndrome Registry / Cunniff et al. 2017): strict sun protection from infancy; annual dermatology + comprehensive skin exam; complete blood count q3-6mo (leukemia surveillance); colonoscopy q1-2y starting age 12-15 with polypectomy; EGD q1-2y from age 12-15; breast MRI + mammography annual from age 18-20 in women; symptom-directed evaluation with low threshold (cancers present atypically and at all ages). Avoid ionizing radiation when possible —... |
Notes
STUB — Wave A+B germline expansion. Linked Indication: none (no Bloom- specific Indication exists yet). Two-Clinical-Co-Lead signoff queued. Critical: only biallelic carriers face the Bloom-phenotype cancer risk. Heterozygous BLM (including BLM-Ash Ashkenazi founder) — at most modest elevation; not currently a routine surveillance indication. Cytotoxic chemotherapy dose-reductions may be required due to underlying genomic instability and bone-marrow fragility — consult with center experienced in Bloom syndrome before any oncologic treatment.
Used By
No reverse references found in the YAML corpus.