2.) (i) Individuals with a mutation in the BRCA1 gene are predisposed to breast
ID: 176800 • Letter: 2
Question
2.) (i) Individuals with a mutation in the BRCA1 gene are predisposed to breast cancer. Explain.
(ii) What is the function of the BRCA1 gene product?
(iii) Why do mutations in BRCA1 result in cancer?
(iv) Why would in not be logical for companies to develop drugs against BRCA1 protein?
(v) Synthetic lethality is an important genetic concept. What does it mean?
(vi) How might synthetic lethality be used to combat BRCA1 tumors?
(vII) BRCA1 mRNA is targeted by several microRNAs, how might a microRNA mutation account for some instances of breat cancer? Would the microRNA be a potential oncogene or tumor suppressor?
Explanation / Answer
i) BRCA1 gene is located on the long arm of chromosome 17. This gene encodes a protien which is involved in repair of DNA damage and transcription regulation of hormone responsive genes.
Mutation in this gene is inherited as an autosomal dominant triat and these mutations are associated with a predisposition to breast cancer. About 85 percent of women carrying one mutant BRCA1allele develops a mutation in the second allele and gets breast cancer. That is why mutations in BRCA1 gene are predisposed to breast cancer.
ii) BRCA1 gene product is 8n valved in DNA repair.
iii). BRCA1 is considered as a tumour suppressor gene. IN case of DNA damage , BRCA1 is phosphorylated by either ATM Kinase or by Chk2 kinase or both. This activated BRCA1 along with other protiens arrests replication during S phase to allow DNA repair.Therefore mutation in this gene renders cell without DNA repair system which in turn is predisposed to cancer.
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