Pseudoxanthoma elasticum and retinitis pigmentosa: dual diagnosis of recessive conditions with ophthalmological consequences.

Background 5.2% of people are carriers for at least two recessive diseases; it can be concluded that a much smaller proportion develop these conditions as two mutated copies of a gene must be present for the disease to manifest clinically. Case presentation We present a 38-year-old Caucasian female affected by two autosomal recessive disorders which can affect the eyes, pseudoxanthoma elasticum (PXE) and retinitis pigmentosa (RP). PXE is an autosomal recessive disorder caused by mutations in ABCC6, affecting 1:25 000 to 1:100 000 people; its classical features involve the dermatological, ophthalmological and cardiovascular systems. Our patient presented with dermatological features of PXE and ophthalmological features of RP. RP presents with significant locus heterogeneity; our patient had biallelic mutations in USH2A. Conclusions This report highlights an interesting case of two unrelated autosomal recessive diseases presenting in one person, both of which have the potential to manifest with ophthalmological symptoms and signs. Though it is likely that only one condition has caused the ophthalmological findings in this case, it raises the question of how we can distinguish the causative disease when two conditions are present that have a shared target organ.