Read the following passage.
BRCA1BRCA1BRCA1 and PTENPTENPTEN are human genes that code for key tumour suppressor proteins. Mutations in BRCA1BRCA1BRCA1 and PTENPTENPTEN can cause breast and ovarian cancers. Inherited and somatic mutations in these genes significantly increase the risk of these malignancies and have been associated with increased susceptibility to other cancers. Genetic testing, using DNA extracted from a peripheral blood sample, can screen for all known harmful mutations in both genes.
Estrogen-receptor (ER)-positive breast cancers have receptors for the hormone estrogen. These cancers develop and progress as a result of increased estrogen concentrations in the blood. Effective treatment of ER-positive breast cancers often involves the use of drugs which have a similar molecular structure to estrogen.
Blood tests can be used to test for specific cancers. Individuals with ovarian cancer often have a high concentration of Cancer Antigen 125 (CA-125) in their blood. However, non-cancerous conditions such as endometriosis, pelvic inflammatory disease (PID), uterine fibroids, and pregnancy can also increase concentrations of CA-125.
Recent development of epigenetic therapies has indicated that several cancers result from epigenetic abnormalities, such as altered promoter methylation. Treatment with epidrugs could be able to reverse the epigenetic changes that cause ovarian cancers.
Use the information in the passage and your own knowledge to answer the following questions.
BRCA1BRCA1BRCA1 and PTENPTENPTEN are human genes that code for tumour suppressor proteins. Mutations in BRCA1BRCA1BRCA1 and PTENPTENPTEN can cause cancer. Explain how.
Genetic testing, using DNA extracted from a blood sample, can screen for all known harmful mutations in both genes. Describe how this DNA could be screened for all known harmful mutations in both genes.
Effective treatment of ER-positive breast cancers often involves the use of drugs which have a similar molecular structure to estrogen. Suggest and explain how these drugs are an effective treatment of ER-positive breast cancers.
Blood tests can be used to test for cancers. However, the results of blood tests may not be conclusive when testing for ovarian cancer using CA-125. Explain why.
Treatment with epidrugs could be able to reverse the epigenetic changes that cause ovarian cancers. Suggest and explain how.
