Practice Exam-Cancer Genetics I and II

Cancer Genetics I and II

Pdf Summary

The provided document consists of practice exam questions on cancer genetics, focusing on genetic risk assessments and specific genetic mutations. It includes questions about retinoblastoma, gastric adenocarcinoma, and ovarian cancer.<br /><br />1. **Retinoblastoma and RB1 Pathogenic Variant Risk**: The first two questions deal with the genetic risk of retinoblastoma possibly being passed to progeny. The risk of transmission is evaluated in different scenarios:<br />   - For a woman who previously had sporadic unilateral retinoblastoma, enucleation, and genetic testing showed typical sporadic case results with no RB1 pathogenic variants in her blood. The risk for her child to inherit a frameshift allele is less than 1%, suggesting a residual risk due to low-level mosaicism.<br />   - In a case without early genetic testing, an estimated 11-13% of unilateral retinoblastoma cases are hereditary, placing a 6% risk on her offspring, calculated as half of the potential personal hereditary risk.<br /><br />2. **Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS)**: The third question addresses the mutational mechanisms leading to these disorders. The most common variants are non-coding promoter mutations that alter the YY1 transcription factor binding site in the APC promoter 1B, distinguishing GAPPS from familial adenomatous polyposis caused by other APC mutations.<br /><br />3. **Ovarian Cancer Genetic Testing**: The final question pertains to genetic testing for ovarian cancer predisposition in a 60-year-old woman. It identifies RAD51C as a gene that, unlike others listed, doesn't pose a high risk for breast cancer but does elevate the risk for ovarian cancer significantly.<br /><br />Overall, the document emphasizes the importance of understanding genetic variants, their mechanisms, and implications for hereditary cancer transmission risk assessments.

Keywords

cancer genetics

genetic risk assessment

retinoblastoma

RB1 pathogenic variant

gastric adenocarcinoma

GAPPS

ovarian cancer

genetic mutations

hereditary cancer

RAD51C