Xeroderma pigmentosum - Skin in Child
Patients with XP present within the first several years of life with sun-induced changes including lentigines and photosensitivity. These patients later develop squamous cell carcinoma, basal cell carcinoma, and melanoma at significantly increased rates along with ocular complications. Neurologic degeneration is present in a quarter of patients.
There are eight known complementation groups associated with XP, each with distinctive genetic loci and phenotypic variants:
XPA – DDB1 protein, most common in Japan
XPB – ERCC3 gene, associated with Cockayne syndrome and trichothiodystrophy
XPC – Endonuclease, most common in US, no neurologic sequelae
XPD – ERCC2, associated with trichothiodystrophy and XP-Cockayne complex
XPE – Mild phenotype, no neurologic sequelae
XPF – Common in Japan, no neurologic sequelae
XPG – Very rare, associated with Cockayne syndrome
XPV – 30% of all cases, no neurologic sequelae
Cockayne syndrome and trichothiodystrophy are also disorders of nucleotide excision repair and patients may display phenotypic features of both syndromes.
Early diagnosis and vigilant sun protection can reduce the morbidity associated with this disease. Compliance with sun protective measures and lifestyle modifications can have psychosocial implications. Overall, life expectancy with XP is dependent on phenotype and level of photoprotection.
For more information, see OMIM.
Q82.1 – Xeroderma pigmentosum
44600005 – Xeroderma pigmentosum
- Erythropoietic protoporphyria (EPP) – Can have similar clinical features to XP with photosensitivity beginning in childhood. Definitive diagnosis can be gained from erythrocyte porphyrins, or late changes can be diagnosed via skin biopsy.
- Congenital erythropoietic porphyria (CEP) – Infants will have extreme photosensitivity and dark urine. Patients will have elevated uroporphyrin I and coporphyrin I.
- Bloom syndrome – Photosensitivity with short stature, characteristic facies.
- Cockayne syndrome – Can have overlap syndromes as mentioned above. Characterized by dwarfism and beaked nose but will lack key features of XP including freckling and skin cancer.
- Rothmund-Thomson syndrome – Photosensitivity with poikiloderma. Will lack freckling and skin cancer as seen in XP.