tailieunhanh - Chapter 064. The Practice of Genetics in Clinical Medicine (Part 3)

Recall of family history is often inaccurate. This is especially so when the history is remote and families become more dispersed geographically. It can be helpful to ask patients to fill out family history forms before or after their visits, as this provides them with an opportunity to contact relatives. Attempts should be made to confirm the illnesses reported in the family history before making important and, in certain circumstances, irreversible management decisions. This process is often labor intensive and ideally involves interviews of additional family members or reviewing medical records, autopsy reports, and death certificates. Although many inherited disorders. | Chapter 064. The Practice of Genetics in Clinical Medicine Part 3 Recall of family history is often inaccurate. This is especially so when the history is remote and families become more dispersed geographically. It can be helpful to ask patients to fill out family history forms before or after their visits as this provides them with an opportunity to contact relatives. Attempts should be made to confirm the illnesses reported in the family history before making important and in certain circumstances irreversible management decisions. This process is often labor intensive and ideally involves interviews of additional family members or reviewing medical records autopsy reports and death certificates. Although many inherited disorders will be suggested by the clustering of relatives with the same or related conditions it is important to note that disease penetrance is incomplete for most multifactorial genetic disorders. As a result the pedigree obtained in such families may not exhibit a clear Mendelian inheritance pattern as not all family members carrying the disease-associated alleles will manifest a clinical disorder. Furthermore genes associated with some of these disorders often exhibit variable expression of disease. For example the breast cancer-associated gene BRCA1 can predispose to several different malignancies in the same family including cancers of the breast ovary and prostate Chap. 79 . For common diseases such as breast cancer some family members without the disease-causing mutation may also develop breast cancer representing another confounding variable in the pedigree analysis. Some of the aforementioned features of the family history are illustrated in Fig. 64-1. In this example the proband a 36-year-old woman IV-1 has a strong history of breast and ovarian cancer on the paternal side of her family. The early age of onset as well as the co-occurrence of breast and ovarian cancer in this family suggests the possibility of an inherited mutation in .