Familial pseudoxanthoma elasticum

Pseudoxanthoma elasticum is an inherited disorder of elastic tissue manifesting itself in a spectrum of disease often involving the skin, cardiovascular system, and the eyes (Gronblad-Strandberg syndrome). E.M. studies have revealed that the disease is due to abnormal formation of elastic fibres rather than degeneration, although a mutation in an elastin gene (ELN) has been excluded as a cause of the disease in one family. Ocular manifestations associated with the condition are classically angioid streaks which represent breaks in Bruch's membrane and which may only be visible by fluorescein angiography. They are usually bilateral and are rarely seen in children, often developing in the second or third decades. Other ocular manifestations include peau d'orange, a stippled appearance resembling the skin changes, often found in association with angioid streaks. Diffuse mottling (salmon spots) may be the earliest or only fundus change in this disease and is often associated with widespread drusen-like spots. A total of 6% of these patients may have associated optic nerve drusen. Gills and Paton reported two brothers, one with angioid streaks and retinal mottling and the other with mottling only. This retinal appearance has subsequently been reported and has been thought to represent an incomplete genetic expression of an autosomal recessive carrier state. Review of the literature between 1896 and 1968 supports the evidence of clinical and genetic heterogeneity of both autosomal dominant and recessive types on review of individual pedigrees. More recently in 1997, Struk et al showed that the recessive and dominant variants of pseudoxanthoma elasticum may be mapped to chromosome 16p13.1.