About This Simulation
In the Medical Genetics Lab, students learn about Mendelian genetics, linkage analysis and finding the defected gene in a family with hereditary breast cancer. Students also learn about the genetics and development of cancer.
Students construct a family pedigree based on gathered information. From this exercise, students get a comprehensive understanding of family pedigrees. Students learn how to read a family pedigree and determine whether or not traits are hereditary. In the hospital introductory scene, students interact with a doctor where they learn about hereditary cancer, Knudson two hits hypothesis and identifying genes that cause hereditary breast cancer a family.
Linkage analysis, Protein Truncation Test and DNA sequencing
After planning their experiment, students arrive in the laboratory and begin experimentation. Students begin with linkage analysis—using four microsatellite markers that are located close to BRCA1 and BRCA2 gene. Students perform PCR to amplify the microsatellite markers and analyze their genotype using gel electrophoresis. Analyzing the genotypes from family members, students determine which gene is linked to hereditary breast cancer in this family.
In breast cancer, mutations in BRCA1 or BRCA2 genes often result in protein truncation. In order to check if there is a mutation in BRCA1 or BRCA2 genes, students will perform Protein Truncation Test (PTT) comparing protein synthesized from the patient’s DNA versus a healthy control. By comparing the resulting protein in polyacrylamide gel electrophoresis, students will be able to conclude whether the patient has a truncated protein. Comparing the results, students conclude if the patient has truncated proteins.
After receiving the PTT result, students need to perform a validation experiment to find out the exact mutation causing the truncated protein. They will perform DNA sequencing of this specific gene and analyze the result. Completing analysis, students perform a validation experiment to find the exact mutation causing truncated proteins. Students perform DNA sequencing of this specific gene and analyze the results.
Cancer, from DNA to metastasis
The case ends with a series of quiz questions assessing student comprehension in topics regarding cancer, oncogenes, tumor suppressor and DNA repairs. Supplementary 3D animation is provided to visually portray cancer progression—defective cells divide uncontrollably and form lumps giving rise to breast cancer and subsequently metastasize to distant tissue in the body.