Family Medical History and Pedigree

The family medical history is an essential part of the genetics consultation. A family history of disease can be obvious (e.g., multiple individuals in consecutive generations affected by hearing loss) or subtle (e.g., several miscarriages as a clue to a balanced translocation). Remember that a disease does not have to run in the family to be genetic (e.g., autosomal recessive diseases and conditions caused by a new [de novo] mutation).

Family history should be organized in a format referred to as a pedigree analysis, which is a standardized approach to constructing a family tree. For a child, the pedigree usually includes three generations (the child’s, parents’, and grandparents’ generations). Make sure to distinguish half-siblings from full siblings and note any nonbiological relatives (e.g., adopted family members).

For each person on the family tree, ascertain the following information:

• biological sex

• age

• health and neurocognitive status

• whether they are living or dead

• if deceased, age at time of death and cause of death

In addition, inquire about the following information:

• if known, the ancestry/ethnicity of the mother’s and the father’s side

• whether the two sides of the family are related (consanguineous) or from the same small geographic region

• if any family members on either side have:

  • a condition resembling the patient’s

  • intellectual disability/autism/neurological problem

  • birth defect or congenital anomaly

  • congenital blindness/deafness

  • two or more miscarriages or a stillbirth

  • childhood, early, or sudden unexplained death

  • cancer (particularly those diagnosed before age 50)

The following resources can help you construct a pedigree:

• Instructions on how to draw a pedigree

• Drawing a pedigree (video)

• Example pedigrees

• Basic pedigree lines and symbols