The skin rash always appears, although sometimes discreetly, which makes the diagnosis more difficult. However, the absence of other clinical symptoms should not eliminate the possibility of IP.
The blisters must not be mistaken with those occurring in cases of herpes, eczema and chickenpox.
A skin biopsy may reveal characteristic anomalies.
Biological tests are used to reveal the presence of the abnormal gene. They can confirm the diagnosis and they greatly help avoid the transmission of the decease .
The other symptoms - tooth disorders, alopecia (patches of hairless skin), or a proliferation of blood vessels on the retina-  make the diagnosis possible when adults are concerned, whether they are mothers and have born a child with IP, or have a mother or sister with IP, or whether they have had several miscarriages with male  foetus.