Background
           Breast cancer is the second most common cancer in women, affecting 1 in 9 by the age of 80. The majority of breast cancers are sporadic, only 5-10% are hereditary. Two genes, BRCA1 and BRCA2, have been linked to an increased risk of breast and ovarian cancer. BRCA1 and BRCA2 have autosomal dominant inheritance, however there is variable penetrance of the disease; there is approximately a 50-85% risk of developing breast cancer by the age of 70.

Patient Information
           Sue Smith was diagnosed with breast cancer at the age of 43. She has a history of early onset breast an ovarian cancer in her family and is concerned about the risk for her daughter. After going over her family history, the genetic counselor determines that Sue is a candidate for genetic testing of the BRCA1 and BRCA2 genes. Sue decides to go ahead with the genetic testing and sends a blood sample off to the lab for analysis.

Results
The results of the automated sequencing are complete and only one mutation was identified. The electropherogram below shows the section containing the mutation. The wild-type gene and protein sequence is shown below the electropherogram.

Questions

  1. What is the mutation?
  2. Does the mutation affect the protein sequence (See the genetic code below)?
  3. Based on your analysis, would the presence of this mutation in Sue's daughters genetically predispose them to breast cancer?