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Difficulty: MediumGastroenterology and Hepatology

Match each hereditary gastrointestinal polyposis or colorectal cancer syndrome with its characteristic genetic mechanism and associated clinical manifestations.

  • Lynch syndromeDefective DNA mismatch repair; significantly increased risk of endometrial, ovarian, and upper gastrointestinal malignancies.
  • Peutz-Jeghers syndromeGermline mutation in STK11; characterized by hamartomatous polyps throughout the gastrointestinal tract and mucocutaneous hyperpigmentation.
  • Gardner syndromeAPC gene mutation; characterized by diffuse colonic adenomatosis associated with osteomas, dental abnormalities, and desmoid tumors.
  • Familial adenomatous polyposisAPC gene mutation; characterized by thousands of colonic adenomas and a nearly 100% lifetime risk of colorectal cancer, classically without extraintestinal tumors.
  • Turcot syndromeAPC or mismatch repair gene mutations; characterized by colonic polyposis and primary central nervous system tumors, such as medulloblastomas.

Answer

Lynch syndrome matches with defective DNA mismatch repair and endometrial/ovarian cancer risk. Peutz-Jeghers syndrome matches with STK11 mutations and mucocutaneous hyperpigmentation. Gardner syndrome matches with APC mutations and osteomas/desmoid tumors. Familial adenomatous polyposis matches with APC mutations causing thousands of polyps classically without extraintestinal tumors. Turcot syndrome matches with colonic polyposis and primary central nervous system tumors.
Each hereditary syndrome has distinct genetic and clinical hallmarks. Lynch syndrome is driven by DNA mismatch repair defects. Peutz-Jeghers syndrome is defined by STK11 mutations. Gardner and Turcot syndromes are distinct clinical variants of adenomatous polyposis; Gardner features bone and soft tissue tumors, while Turcot features primary brain tumors. Classic familial adenomatous polyposis strictly presents with massive colonic adenomatosis.

Step-by-Step Solution

1
Evaluate Lynch syndrome.
Associated with DNA mismatch repair mutations and extracolonic cancers (endometrial, ovarian).
It is the most common hereditary colorectal cancer syndrome and is non-polyposis.
2
Evaluate Peutz-Jeghers syndrome.
Associated with STK11 mutations, hamartomatous polyps, and mucocutaneous hyperpigmentation.
The combination of hamartomas and lip pigmentation is pathognomonic for this syndrome.
3
Evaluate Gardner syndrome.
Associated with APC mutations along with osteomas, dental anomalies, and desmoid tumors.
It is distinguished from classic FAP by these specific benign extraintestinal soft tissue and bone manifestations.
4
Evaluate Familial adenomatous polyposis.
Associated with classic APC mutations causing profound colonic adenomatosis.
This is the fundamental presentation of the APC tumor suppressor gene mutation, guaranteeing colon cancer if a colectomy is not performed.
5
Evaluate Turcot syndrome.
Associated with either APC or mismatch repair mutations combined with central nervous system malignancies.
The eponym Turcot specifically highlights the brain tumor and polyposis association.

Key Concept

Hereditary Gastrointestinal Polyposis and Cancer Syndromes
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Topics

Gastroenterology and Hepatology

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