Xeroderma pigmentosum (XP) is a rare, autosomal recessive disorder of DNA repair. Affected
individuals are unable to repair ultraviolet radiation (UVR)-induced DNA damage, leading to a variety
of clinical manifestations: a dramatic increase in mucocutaneous malignancies, increased lentigines,
extreme photosensitivity (in approximately 50% of cases), and neurodegeneration (in approximately
30% of affected individuals). Incidence in Western Europe is recorded as 2.3 per million live births. There
are eight different complementation groups, XP-A to XP-G, and XP-variant (XP-V) corresponding to the
eight affected genes. Classically, XP patients were identified by clinicians for their tendency to develop
severe and exaggerated sunburn on minimal sun exposure, however recently it has been shown that
XP-C, XP-E and XP-V patients have normal sunburn reactions for skin type compared to the other
groups, who suffer not only with severe, exaggerated sunburn, but also have an increased incidence
of neurodegeneration.
A diagnosis of XP should be considered in a child with either severe sunburn, increasing lentigines at
exposed sites, or development of multiple skin cancers at an early age. Skin biopsy and subsequent
testing in cell cultures for defective DNA repair, confirms or excludes the diagnosis. Mean life expectancy
is reduced; the two main causes of mortality are skin cancer and neurodegeneration. These clinical
features distinguish XP from other disorders of DNA repair, namely Trichothiodystrophy and Cockayne
syndrome, although overlapping syndromes do occur. Instigation of meticulous photoprotection for
all XP patients has been shown to reduce both the lentigines and number of skin cancers dramatically
and would be presumed to increase life expectancy. Compliance with photoprotection is a recognised
problem amongst XP patients, particularly in those without easy sunburn. This is further accentuated by
lack of social acceptance for people who wear UVR-protective visors. Increased awareness of XP,
both within the medical and media spheres will benefit current and future XP patients; this will
aid earlier diagnosis and timely photoprotection, with better compliance, and therefore, result in an
improved prognosis