3.5 Syndromes similar to Pitt Hopkins

3.5 Overlapping phenotypes

Sometimes, people look and behave a lot like people with Pitt Hopkins syndrome, but don't quite qualify for a Pitt Hopkins diagnosis. When their DNA is checked, no changes in the part coding for Transcription Factor 4 is found. Some of these have Pitt-Hopkins-like syndromes I and II. A number of people were suspected to have Pitt Hopkins, but when no mutation in TCF-4 was found, the scientists checked their characteristics again and decided they did not actually have all the clinical diagnostic criteria necessary for the Pitt Hopkins diagnosis.^40,41 

When it looks like someone has Pitt Hopkins syndrome, but no change in the DNA coding for TCF-4 is found, other syndromes should be considered. For instance, they may have Angelman syndrome, Kleefstra syndrome or Mowat-Wilson syndrome, or a number of other syndromes. Because the way these people look, act and develop overlaps with Pitt Hopkins, scientists talk about 'overlapping phenotypes'.