A first-degree relative of the patient (parent, sibling, or child) has a documented posit...

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

ID	`RF-CASCADE-FAP-FDR-POSITIVE`
Type	Red flag
Status	reviewed 2026-05-19 \| pending_clinical_signoff
Diseases	`DIS-CRC` `DIS-GASTRIC` `DIS-PDAC` `DIS-PROSTATE`
Sources	`SRC-ASCO-ACMG-LYNCH-2014` `SRC-ESMO-CRC-2024` `SRC-NCCN-COLON-2025` `SRC-NCCN-GENETIC-FAMILIAL-CRC-2025`

Red Flag Origin

Definition	A first-degree relative of the patient (parent, sibling, or child) has a documented positive germline test result for the APC gene (familial adenomatous polyposis — FAP, including the attenuated AFAP and Gardner variants). The patient themself has NOT yet been germline-tested and has no current personal cancer diagnosis. Per autosomal-dominant inheritance, the patient (regardless of current age — including pediatric patients) carries a 50% prior probability of also being an APC carrier. Because classic FAP surveillance begins at age 10-12 (annual sigmoidoscopy) and classic FAP carries near-100% lifetime CRC risk by age 40 without colectomy, the cascade-testing question is time-critical in pediatric first-degree relatives. Distinct from RF-FAP-FAMILY-HISTORY-SUSPICION (fires on pedigree pattern alone, before any relative has tested positive) and from RF-FAP-CONFIRMED-CARRIER (fir...
Clinical direction	investigate
Category	other

Trigger Logic

{
  "any_of": [
    {
      "finding": "family_first_degree_relative_apc_carrier_confirmed",
      "value": true
    }
  ],
  "type": "lab_value"
}

Notes

v0.2-B cascade-testing pilot (2026-05-19). Fires when a first-degree relative (FDR — parent, sibling, child) of an asymptomatic patient has a confirmed positive germline test for APC. Engine routes to PreventionPlan recommending: (a) IND-CASCADE-FAP-FDR-POSITIVE-TESTING (standard) — cascade site-specific (familial-variant) APC testing for the patient **from age 10-12** (childhood-onset surveillance dependency). Pre/post-test counseling addresses childhood-onset sigmoidoscopy initiation in classic FAP, lifetime CRC risk, and prophylactic colectomy timing in late teens / early 20s. Modern multi-gene panels include MUTYH for MAP differential (autosomal-recessive vs autosomal-dominant FAP). (b) IND-CASCADE-FAP-FDR-POSITIVE-SURVEILLANCE (alternative) — empirical sigmoidoscopy from age 10-12 per InSiGHT FAP protocol for patients who decline cascade germline testing, applied as if classic FAP were confirmed until testing settles the question. Upper-GI EGD q1-3y from age 25-30 also applied empirically. **50% prior probability** in autosomal-dominant inheritance (one parent heterozygous) — combined with the time-critical childhood surveillance start and the near-100% CRC penetrance of clas...

Used By

Indications

IND-CASCADE-FAP-FDR-POSITIVE-SURVEILLANCE - IND-CASCADE-FAP-FDR-POSITIVE-SURVEILLANCE
IND-CASCADE-FAP-FDR-POSITIVE-TESTING - IND-CASCADE-FAP-FDR-POSITIVE-TESTING