Family history skills and inheritance
One of the questions most commonly asked by primary care professionals is whether there is a family history of disease. Questions are asked both at new patient registration and during ongoing management. The significance of family history of disease may not be readily apparent if the primary care professional does not recognise its importance in certain clinical conditions. It is recognised as a risk factor in multifactorial diseases such as coronary heart disease and cancers. The importance of family history has been identified by the National Institute for Clinical Excellence (NICE) in its Cancer Plan, in the identification of individuals at high risk of sudden cardiac death, and in the identification of those with renal disease such as polycystic renal disease. The Royal College of General Practitioners (RCGP) states in its genetics curriculum that the drawing of a family tree, its interpretation and a knowledge of inheritance patterns are key to the basic investigation of an individual who may be at risk of a genetic condition.
There is a major difference between how the regional genetics service might take a family history in order to determine its clinical significance, and the abbreviated way in which a family history would be taken in primary care, depending on the presentation of the consultand (the person seeking genetic advice about a genetic disorder).
Family history taking by a geneticist usually involves taking a history from an affected individual, taking a three-generation pedigree, making a risk assessment, developing a management strategy (which includes verifying the family history through the use of cancer registers or pathology reports from treating hospitals), and considering genetic testing as well as offering follow-up and support.7
Most primary care professionals cannot offer as much dedicated time as the geneticist. Family history tools are available but, like any screening method, they must have defined clinical validity and clinical utility. Most primary care practices would use the new patient registration process to elicit details about the family. Patients may present with concerns about their family history (e.g. cancer) or their reproductive risk (e.g. Down's syndrome or haemoglo- binopathies). Although in clinical genetics there are pedigree-drawing programs available, which use standard pedigree symbols,8 these programs are little used in primary care, and the problem of how to store the information from family history questionnaire templates or from computer pedigree drawing programmes on the electronic health record has not yet been resolved.
Clearly the questions that need to be asked during family history taking depend on the suspected clinical condition, and Box 1.1 lists some of the basic questions that could be asked during the evaluation of a patient who is concerned about their family history. The importance of the information that is obtained will depend on the primary care professional's knowledge of the inheritance patterns and the importance of heritability in the risk of developing a disease. The role of the regional genetics centre must be to help to formulate referral guidelines that are easily accessible to primary care and which will aid risk stratification.
Box 1.1: Taking a family history: hints and tips9
Pre-printed pedigree sheets are available from regional genetics centres, and standard pedigree symbols are used as defined by the Pedigree Standardisation Task Force.7 The following information indicates the standard abbreviated family history questions (adapted from the Pedigree Standardization Task Force recommendations for standardized human pedigree nomenclature8) that might be asked in primary care, together with the standard pedigree symbols. See Figures 1.1-1.4 on pp. 9-12 and A1-A4 on pp. 126-7.
- 1 Ensure that the pedigree is named and dated.
- 2 When drawing the pedigree, the male partner should be on the left.
The proband or the index case is the affected individual for whom the family history is ascertained. The proband should be labelled with the letter P. The consultand is the person seeking advice who may not be affected.
- 3 Siblings are in birth order, with the firstborn on the left.
- 4 The names of relatives should be recorded.
- 5 Dates of birth of relatives should be recorded
- 6 Ask about dates of diagnoses, including age when affected, place where diagnosed, age at death and cause of death.
- 7 Disease symbols should be used in the key to follow disease patterns through generations.
- 8 Ask about stillbirths and miscarriages.
- 9 Ask about consanguinity.
- 10 Ask about ethnicity.
The results of clinical investigations, including genetic testing, should be included.