Inheritance of Gardner syndrome is
## **Core Concept**
Gardner syndrome is a variant of Familial Adenomatous Polyposis (FAP), characterized by the presence of multiple colonic polyps, osteomas, skin and soft tissue tumors, and dental abnormalities. It is an autosomal dominant disorder.
## **Why the Correct Answer is Right**
Gardner syndrome is inherited in an **autosomal dominant** pattern. This means a mutation in one of the two copies of the gene (located on chromosome 5q21-22) is sufficient to cause the condition. The responsible gene is the **APC gene** (Adenomatous Polyposis Coli), which acts as a tumor suppressor. A variety of mutations in the APC gene can lead to Gardner syndrome, resulting in the development of hundreds to thousands of polyps in the colon and rectum, significantly increasing the risk of colorectal cancer.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because Gardner syndrome does not follow an **autosomal recessive** pattern of inheritance. In autosomal recessive disorders, an individual must inherit two copies of the mutated gene (one from each parent) to express the condition.
- **Option B:** This option is incorrect because Gardner syndrome is not **X-linked**. X-linked disorders are caused by mutations in genes on the X chromosome, and their inheritance patterns differ between males and females.
- **Option C:** This option is incorrect because Gardner syndrome does not exhibit **variable penetrance** as its primary mode of inheritance. While variable penetrance (the degree to which a genotype is expressed in an individual's phenotype) can be observed in some cases, it does not describe the inheritance pattern.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that patients with Gardner syndrome require **prophylactic colectomy** due to the high risk of colorectal cancer. Early diagnosis and management are crucial to prevent cancer development. Screening for Gardner syndrome should be considered in patients with multiple osteomas or skin and soft tissue tumors, particularly if there is a family history of FAP or Gardner syndrome.
## **Correct Answer:** . Autosomal dominant