Core Principles in Family History: Overview

The principles for family history collection, interpretation, and intervention are listed here in an order that reflects common clinical practice. Each institution’s clinic flow and patient-specific situations will affect the order in which clinicians should apply the following principles.

A multidisciplinary working group developed the core principles and the associated PowerPoint slides primarily as educational tools for those who train clinicians. These principles and associated information do not provide information for general or disease-specific risk assessment, recommendations for disease treatment or management, or guidelines for managing work flow. As such, the core principles are intended for educational purposes. The content is not intended to serve as formal guidelines for clinical practice nor as approved or recommended approaches for diagnosis or treatment of disease.

The following provides a summary of the Core Principles in Family History. There is more detailed information available for each section, accessible through the menu or by clicking the appropriate section. A slide set with these principles and associated cases is available on the Tools and Downloads page.

Collection

1. Recognize and understand standard pedigree symbols 

2. Produce at least a three-generation family history that:

Identifies

• The patient and
• The historian, or person providing the information. This person may be the patient or someone else, such as a parent.

And Includes

• The patient and his or her first-, second-, and third-degree relatives;
• Information for maternal and paternal sides of the family;
• Degree of relationship, including: full or half siblings, children with same or different partner(s);
• Affected and unaffected relatives;
• Date of collection (or date of update), and the name of collector (or updater); and
• Legend or key, if symbols are used to designate disease

• Age, birth date, or year of birth
• Relevant health information, including test results if applicable
• Diagnosis and age at diagnosis
• Age at death, or years of birth/death
• Cause of death
• Ancestral background for each biological grandparent
• Infertility, or no children by choice
• Pregnancies
• Pregnancy complications with gestational age noted, including miscarriages, stillbirths, ectopic pregnancies, pregnancy terminations, preterm birth, preeclampsia, and bleeding/clotting complications
• Consanguinity (blood relationship of parents)

Interpretation

1. Recognize Genetic Red Flags

• Family history of known or suspected genetic disorder
• Multiple affected family members with same or related disorders
• Earlier age at onset of disease than expected
• Developmental delays or mental retardation
• Diagnosis in less-often-affected sex
• Multifocal or bilateral occurrence in paired organs
• One or more major malformation(s)
• Disease in the absence of risk factors or after preventive measures
• Abnormalities in growth (growth retardation, asymmetric growth, excessive growth)
• Recurrent pregnancy losses (2+)
• Consanguinity (blood relationship of parents)
• Ethnic predisposition to certain genetic disorder

• Multi-factorial (complex) disorders
• Single-gene disorders:  autosomal dominant, autosomal recessive, X-linked
• Chromosomal disorders: extra or missing chromosomes; large-scale deletions; translocations
• Mitochondrial

• Missing information vs. unaffected relatives
• Reliability of information
• Non-traditional families
• Unknown paternity
• Adoption
• Cultural definitions of family
• Cultural biases
• Consanguinity
• Confidentiality

Intervention

1.   Identify where more specific information is needed and obtain records

2.   Assess general risks

3.   Know when to refer to genetic professionals

4.   Encourage the patient to talk to other family members

5.   Update pedigree at subsequent visits