WBR0770

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics
Sub Category	SubCategory::Oncology
Prompt	[[Prompt::A 48 year old woman, previously healthy, presents to the physician's office for a left breast lump. She explains that she incidentally palpated the lump during showering. She does not complain of any pain or breast discharge. Following appropriate work-up, she is diagnosed with breast cancer. Genetic analysis shows that she is positive for BRCA1. When asked, the physician explains the normal function of BRCA1. What is the gene product of BRCA1?]]
Answer A	AnswerA::DNA repair protein
Answer A Explanation	AnswerAExp::BRCA1 and BRCA2 are tumor suppressor genes whose gene product is a DNA repair protein.
Answer B	AnswerB::Transcription factor
Answer B Explanation	AnswerBExp::Examples of genes that encode transcription factors are C-myc, L-myc, and N-myc, which are oncogenes associated with Burkitt's lymphoma, lung cancer, and neuroblastoma, respectively.
Answer C	AnswerC::Tyrosine kinase
Answer C Explanation	AnswerCExp::Examples of genes that encode tyrosine kinase are abl, HER/neu, and ret oncogenes, which are associated with CML, breast cancer, and MEN II syndromes, respectively.
Answer D	AnswerD::GTPase
Answer D Explanation	AnswerDExp::An example of a gene that encodes GTPase is ras oncogene that is associated with colon cancer.
Answer E	AnswerE::Cytokine receptor
Answer E Explanation	AnswerEExp::An example of a gene that encodes a cytokine receptor is c-kit oncogene that is associated with gastrointestinal stromal tumors (GIST)
Right Answer	RightAnswer::A
Explanation	[[Explanation::BRCA1 and BRCA2 are tumor suppressor genes that are associated with breast cancer and ovarian cancer. BRCA genes encode DNA repair proteins normally. Hence, their loss in cancers lead to inhibition of synthesis of DNA repair proteins and facilitation of cancer growth. Educational Objective: BRCA tumor suppressor genes encode for DNA repair proteins. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::breast, WBRKeyword::cancer, WBRKeyword::oncogene, WBRKeyword::tumor, WBRKeyword::suppressor, WBRKeyword::gene, WBRKeyword::genes, WBRKeyword::encode, WBRKeyword::product, WBRKeyword::protein, WBRKeyword::DNA, WBRKeyword::repair, WBRKeyword::BRCA1, WBRKeyword::BRCA2, WBRKeyword::lump
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::