Historically it encompassed only rare Mendelian disorders and chromosome abnormalities with multisystem phenotypes. Because of their medical complexity combined with the risk to other family members and the psychosocial issues that arise when dealing with issues of inheritance, these cases were best handled by geneticists and genetic counselors.
genomics0909.qxp 8/25/09 9:52 AM Page 61 GENOMICS IN PA PRACTICE E RY N N G O R D O N , M S , C G C What PAs should know before they refer patients to a genetic counselor edical genetics is an evolving would be at a 50% risk to inherit it as Several months later the couple decid- M field. Historically it encom- passed only rare Mendelian disorders and chromosome abnormali- well. Those who carry a BRCA muta- tion have a 65% to 85% lifetime risk of breast cancer1,2 and an 11% to 54% ed, for their daughters’ sake, to pro- ceed with testing. After blood was drawn, the patient ties with multisystem phenotypes. Be- lifetime risk of ovarian cancer.1,2 made an appointment with the genetic cause of their medical complexity com- The counselor offered genetic test- counselor to receive the results in per- bined with the risk to other family ing to determine whether the patient son. Two days before that appoint- members and the psychosocial issues carried a BRCA mutation. In addition ment, the patient called to cancel, that arise when dealing with issues of to the implications for her daughters, explaining that she could not handle inheritance, these cases were best han- a positive result would mean that the the information at that time. Several dled by geneticists and genetic coun- patient herself was at increased risk follow-up calls and cancelled appoint- selors. Now, a growing number of dis- for developing a second breast cancer ments later, she came in for her results. eases have been recognized as having and/or ovarian cancer. Given the (Figure 1 shows her genetic pedigree.) a genetic basis, and relegating genetics weight of this information, she and Though not surprised that she tested just to the geneticists and genetic coun- her husband decided that they needed positive for a BRCA1 mutation, the selors has become more difficult. More- to think about whether they were patient was devastated by the implica- over, identification of those aspects of ready to know more and to share this tions this would have for her daugh- genetics that can be incorporated into information while they were in the ters. The genetic counselor offered to primary care has become more impor- midst of dealing with the current work with the patient to share this tant. Key to this process is identifying breast cancer diagnosis and treatment. information with her daughters and when to refer a patient to a geneticist or a genetic counselor. Many factors Maternal Ancestry: Ashkenazi Jewish come into play, as demonstrated by the following case: Paternal Ancestry: Ashkenazi Jewish ›CASE STUDY 1 2 A 50-year-old woman of Ashkenazi Jewish ancestry has been given a diag- I nosis of invasive breast cancer; her d. 48 yo 76 yo mother died of breast cancer at 48 years, Dx 45 yo and her sister’s ovarian cancer was diag- nosed at age 52. Based on that history, the woman was at risk of carrying a mutation in BRCA1 or BRCA2, the 1 2 3 two genes known to cause hereditary II Invasive Breast Cancer breast and ovarian cancer syndrome. 54 yo 50 yo 53 yo After meeting with a genetic coun- Dx 50 yo Dx 52 yo Ovarian Cancer selor w
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