Co-existence of hereditary coproporphyria and porphyria cutanea tarda: The importance of genetic testing.

The porphyrias are a group of inherited disorders that result in defects in the enzymes of the haem biosynthetic pathway, causing photosensitive bullous skin eruptions or abdominal and neurological attacks. Enzymatic defects result in specific porphyrin excretory patterns that are diagnosed biochemically and can be confirmed by genetic testing. Defects in the coproporphyrinogen oxidase (CPOX) enzyme result in the autosomal dominant hereditary coproporphyria. Multiple mutations have been identified in the CPOX gene and incomplete penetrance is noted. Latent carriers without clinical evidence of disease are at risk of life-threatening attacks. Porphyria cutanea tarda may be inherited, but is more commonly acquired. Occasionally two forms of porphyria may co-exist. The importance of genetic testing is discussed.

Haem arginate as effective maintenance therapy for hereditary coproporphyria.

A 35-year-old woman presented with skin fragility and photosensitivity with blisters affecting her face and hands. Other symptoms included intermittent headache, fatigue, abdominal pain and nausea. Porphyrin studies were markedly raised, with features consistent with hereditary coproporphyria (HCP). Despite strict precautions, symptoms remained significantly problematic. Regular haem arginate infusions of 3 mg/kg per day over 4 days on a monthly basis were commenced and resulted in significant improvement of the patient's symptoms and a reduction in urinary porphobilinogen. Although haem arginate infusion is known as a treatment for severe acute attacks of HCP, the effectiveness of regular infusions as maintenance therapy has not been established. This is the first report of effective symptom control correlating with normalization of biochemical markers in a patient receiving regular haem arginate infusions for the treatment of HCP.