Confirmed germline pathogenic / likely-pathogenic variant in FLCN (folliculin) — Birt-Hog...

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

ID	`RF-BHD-FLCN-CONFIRMED-CARRIER`
Type	Red flag
Status	reviewed 2026-05-20 \| pending_clinical_signoff
Diseases	`DIS-RCC`
Sources	`SRC-NCCN-GENETIC-FAMILIAL-BREAST-OVARIAN-2025`

Red Flag Origin

Definition	Confirmed germline pathogenic / likely-pathogenic variant in FLCN (folliculin) — Birt-Hogg-Dubé syndrome (BHD). Autosomal-dominant. Classic clinical triad: fibrofolliculomas (skin papules of face/neck/ upper trunk, often dermatologic presenting feature), pulmonary cysts + spontaneous pneumothorax (cumulative lifetime pneumothorax ~30-40%; imaging shows multiple basal/subpleural cysts), and renal cell carcinoma (~16-32% lifetime risk; characteristic chromophobe + hybrid oncocytic + clear-cell histologies; bilateral + multifocal common; often presents younger — 40s-50s — than sporadic RCC). FLCN encodes folliculin, an mTOR pathway regulator; loss-of-function variants cause BHD. Patient has confirmed positive germline test; no current personal cancer diagnosis in the carrier being assessed. Prevention-persona RedFlag (§20, v0.3 rare-hereditary expansion Wave P2).
Clinical direction	investigate
Category	other

Trigger Logic

{
  "any_of": [
    {
      "finding": "germline_flcn_pathogenic_variant_confirmed",
      "value": true
    },
    {
      "finding": "birt_hogg_dube_clinical_criteria_met",
      "value": true
    },
    {
      "finding": "bhd_fibrofolliculoma_phenotype_documented",
      "value": true
    }
  ],
  "type": "lab_value"
}

Notes

Prevention-persona RedFlag for BHD/FLCN confirmed carriers. Multi- organ surveillance: abdominal MRI q2-3y from age 20 for RCC (avoid radiation; many BHD lesions are hybrid oncocytic + slow-growing); chest HRCT baseline + symptom-driven (spontaneous pneumothorax triggers high-resolution imaging); dermatology q1y for skin surveillance. Nephron-sparing surgery (partial nephrectomy) preferred for ≤3cm renal lesions given multifocal/bilateral disease pattern. STUB pending two-Co-Lead signoff per CHARTER §6.1 dev-mode.

Used By

Indications

IND-BHD-FLCN-CARRIER-OBSERVATION - IND-BHD-FLCN-CARRIER-OBSERVATION
IND-BHD-FLCN-CARRIER-SURVEILLANCE - IND-BHD-FLCN-CARRIER-SURVEILLANCE