Molecular analysis of the UROD gene in 17 Argentinean patients with familial porphyria cutanea tarda: characterization of four novel mutations.

Porphyria cutanea tarda (PCT) is caused by decreased activity of uroporphyrinogen decarboxylase (UROD) in the liver. The disease usually occurs in adulthood and is characterized by cutaneous photosensitivity, hyperpigmentation, skin fragility and hypertrichosis, due to the accumulation of porphyrins produced by oxidation of uroporphyrinogen and other highly carboxylated porphyrinogens overproduced as a result of the enzyme deficiency. PCT is generally sporadic, but about 20-30% of patients have familial-PCT (F-PCT) which is associated with heterozygosity of mutations in the UROD gene. In the present study we have found the molecular defect in seventeen unrelated Argentinean patients with F-PCT, identifying a total of eleven UROD gene mutations: four novel and seven previously described. The novel mutations were: a guanine insertion at the 5' splice junction of intron 2, a three nucleotide deletion causing the lost of valine 90, a deletion of 22 bp in exon 6 and a deletion of part of the polyadenylation signal. Prokaryotic expression studies showed that the novel amino acid deletion resulted in an inactive protein. Mutations c.10insA and p.M165R, previously found in Argentinean patients, were recurrent in this study; they are the most frequent in Argentina accounting for 40% of the mutant alleles characterized to date.

Pre-treatment serum lactate dehydrogenase level is an important prognostic factor in high-grade extremity osteosarcoma.

BACKGROUND: Treatment of high-grade osteosarcoma remains a challenge. The prognostic significance of the pre-treatment serum lactate dehydrogenase (LDH) level is currently controversial. PATIENTS AND METHODS: We reviewed records from all patients diagnosed with conventional high-grade osteosarcoma at our institution over a 25-year period and analysed the prognostic significance of LDH in high-grade localised extremity osteosarcomas treated with chemotherapy. RESULTS: Between June 1977 and March 2003, 66 patients for whom follow-up was available were diagnosed with localised high-grade extremity osteosarcoma and treated with chemotherapy. The median age was 15 years, with only 3% older than 40 years, and the median follow-up was 100 months. The median progression-free survival (PFS) was 67 months and the median overall survival (OS) was 113 months. The absence of a response to chemotherapy was correlated with a trend toward lower PFS and OS. High serum pre-treatment LDH level was associated in multivariate analyses with a poorer prognosis for both PFS (HR=8.623, 95%CI: 1.71-43.37; p=0.009) and for OS (HR=9.38; 95%CI: 1.73-50.74; p=0.009). CONCLUSION: In this series, the pre-treatment serum LDH level had an independent prognostic value for both PFS and OS in patients with high-grade localised extremity osteosarcoma. This measurement should be included in a large prospective prognostic series.