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Step 1.b: Review Collected Data—Family History and the Use and Interpretation of the Pedigree

Objectives

1.   Discuss common terms used in constructing a pedigree

2.   Describe basic elements of the pedigree

3.   Discuss the three-generation pedigree and the significance to health and illness

4.   Conduct a family history using a three-generation pedigree

The family history is vital to the genomic risk assessment. Family history plays a significant role in health care, and with the evolution of medical genomics it is believed that family history contributes to the advancement of personalized health care (Wilson et al., 2012). When used with the personal history, it can (a) inform diagnosis; (b) promote risk assessment to estimate an individual’s risk of developing a specific condition through risk stratification (e.g., population/average risk, moderate risk, or high risk); (c) provide a means for the prevention, diagnosis, and management of disease, with the primary emphasis on prevention; and (d) establish rapport through risk communication, allowing better health-related decision making regarding disease risk and management of care (National Coalition for Health Professional Education in Genetics [NCHPEG], 2016).

One of the most important risk assessment tools is the family history in the form of a three-generation pedigree. A positive family history is associated with a higher risk of a disorder when multiple family members who are first- and second-degree relatives are affected with a disease and/or the disease occurs at a younger age than normally seen in the general population. The family history is representative of the family’s shared genes, environment, and behaviors (Wilson et al., 2012). Families with positive histories for frequently occurring disorders such as diabetes or heart disease have a two- to fivefold greater relative risk for disease occurrence than the general population (Reid & Emory, 2006). Advanced practice registered nurses (APRNs) can use the three-generation pedigree to offer important diagnostic and screening interventions appropriate for the identified disorder as well as preventive measures to reduce or prevent disease occurrence.

The types of family assessment include comprehensive and targeted histories (NCHPEG, 2016). The comprehensive family history is an in-depth assessment of major medical concerns, chronic medical conditions, hospitalization, surgeries, birth defects, and intellectual disabilities including mental retardation, learning disabilities, or developmental delays that may occur in the family. In contrast, a targeted family history directs questions related to a particular disorder (e.g., cancer, heart disease, hearing loss), either concerning a positive family history of disorders in relatives or an individual’s history of present illness (NCHPEG, 2016). In the clinical setting, the level 53of suspicion based on personal history or other data influences the collection and application of the family history. Using information gleaned from the family history and coupled with the personal history and ancillary data, provisions can be made for patients based on their disease risk. For example, individuals with multiple family members who have a disorder (e.g., first- and second-degree members with breast cancer) may indicate the need for further evaluation to determine if the patient has a predisposition to breast cancer based on an inherited genetic disorder (e.g., hereditary breast and ovarian cancer [HBOC] due to mutation in a BRCA gene or other inherited breast cancer genes). Individuals with a genetic mutation for most breast cancer syndromes would be considered at high risk for the disease. In contrast, a patient whose personal and family history is unremarkable or uneventful may be at average or population risk for breast cancer. The family history with other data (personal history) aids in determination of a probability for disease risk; implementation of screening measures for early detection of disease, behavioral modifications (e.g., smoking cessation), or chemoprevention to reduce risk (e.g., aspirin therapy and cardiovascular disease); or consideration of risk-reducing surgery to further reduce risk.

Family history is an important tool for prevention and disease recognition that can be applied to various settings. Collection of family history data should be a continuous process that is evaluated and updated during each client contact (Bennett, 2010).

Three-Generation Pedigree

A basic pedigree consists of a minimum of three generations: first-degree relatives (e.g., parents, children, siblings), second-degree relatives (half siblings, grandparents, aunts and uncles, grandchildren), and third-degree relatives (cousins, great-grandparents, great-grandchildren). The consultand is the person with the appointment, seeking health care or genomic health information. This person is identified on the pedigree with an arrow. The consultand can be healthy or a person with a medical condition. The proband is the affected individual who brings the family to medical attention and may not be present during the appointment with the consultand. An individual can assume both roles, that of the consultand and the proband. The three-generation pedigree provides a graphic picture of how family members are biologically related to each other, from one generation to the next. Generally, the pedigree is collected face to face prior to the physical exam. Figures 5.1 and 5.2 are examples of family pedigrees depicting members of multiple generations for both the maternal and paternal lineages. The figures include placement of members pertaining to the first, second, and third generation in the family as well as their relationship lines, and whether the member is alive or deceased. This forms the basic structure of the therapy. Additional data such as ancestry of origin and specific information regarding medical or surgical history; prior genetic testing, if applicable, with results; and other pertinent data are needed. An inclusion of a legend or key is a part of the pedigree as it pertains to specific medical or disease history.

Due to the amount of information required, many providers are using forms to have the patient document detailed information prior to the office visit. This method allows the patient additional time to inquire about previously unknown family history and procure documents, if needed (e.g., death certificates), as well as allows the health care provider time to review the information prior to the patient’s appointment if the family history data are sent prior to the patient visit. In addition, if administrative services are provided, having the family history data prior to the appointment can allow time for preparation of the information in a pedigree format.

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