Family history is sometimes important in diagnosis. Although there are situations in which an elaborate family pedigree is needed, in many situations one can get far with some basic data.
Example to work through
One can specify family history from the Start screen of the software by clicking the light green Transmission button. Here you can indicate that the parents are unaffected but one of 2 older sisters is affected, a history suggestive of autosomal recessive inheritance:
This is a positive family history, denoted on the Start screen by a green check mark on the Transmission button:
Often one doesn’t start out by discussing family history, but family history can be suggested as useful, as shown here for an 8-month-old boy with recent onset of kyphosis and macrocephaly: (Registered users can click the images below to jump into the software; some videos may be helpful in navigating from there)
Clicking the component to the left of the Transmission History finding, one call fill in the positive family as illustrated in the first image. This increases the probability of recessive diseases such as MPS1 and MPS7:
One can view the expected family history for the diseases in the differential diagnosis by clicking on the green V on the top black navigation bar. For recessive diseases, a family history of unaffected parents and an affected sibling is common. In contrast, for “O’Donnell-Luria-Rodan syndrome”, a dominant disease with a high de novo mutation rate, it is unlikely that one would expect an affected sister.
As seen in this example, family history can have a significant effect on the differential diagnosis, and the error in not using it is that there is less data to inform the differential diagnosis.
This page is part of a series on the Elements of Diagnosis.
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