Familial idiopathic intracranial hypertension and variegate porphyria-is there any connection?: Report of three sisters

There are at least 12 previous reports of familial occurrence of idiopathic intracranial hypertension (IIH), suggesting the presence of a genetic factor. The authors report two sisters with IIH and a third sister with variegate porphyria (VP). A review of VP is presented. The mode of inheritance of IIH cannot be determined but may be autosomal dominant with variable expressivity and reduced penetrance of the phenotype. VP, which is inherited in this manner, can give rise to virtually all kinds of neuropathy. In addition, the two disorders have other similar features. Thus, there were reasons to consider the possibility that IIH was a manifestation of VP. However, a detailed comparison of IIH and VP showed the similarities to be incomplete and the differences pronounced, and in the sisters with IIH biochemical tests for VP did not support the hypothesis. The coincidence was probably fortuitous, but for definite conclusions, testing would have been required also in the acute stage of IIH. This was not possi...