Pseudoxanthoma elasticum: significance of limited phenotypic expression in parents of affected offspring.
The inheritance pattern of pseudoxanthoma elasticum (PXE) is controversial. Inheritance patterns are confounded by delayed diagnosis and mild or limited phenotypic expression among certain family members. Because testing for the genetic mutation(s) responsible for PXE is not routine, genetic counseling must be done with caution. We describe 4 families in which one or more children were diagnosed with PXE. Detailed examination of the parents was carried out, including skin biopsy and ophthalmologic examination. In 3 of the 4 families, one parent had limited phenotypic expression, such as ocular findings without skin lesions or very mild skin lesions with no ocular findings. In the other family, one parent had very mild skin and ocular disease. All 4 affected parents had diagnostic skin biopsy findings. In none of the 4 families was the inheritance pattern clear-cut. Although the inheritance pattern of PXE has been debated, clinically significant stigmata of PXE, which are not always readily apparent, can occur in successive generations. Therefore all first-degree relatives of affected patients should receive a full dermatologic examination as well as a funduscopic examination. If even mild typical skin or eye findings are present, then skin biopsy should be performed.