RNA analysis of consensus sequence splicing mutations: implications for the diagnosis of Wilson disease.

Wilson disease (WD) is an autosomal recessive disorder caused by a defective function of the copper-transporting ATP7B protein. This results in progressive copper overload and consequent liver, brain, and kidney damage. Approximately 300 WD-causing mutations have been described to date. Missense mutations are largely prevalent, while splice-site mutations are rarer. Of these, only a minority are detected in splicing consensus sequences. Further, few splicing mutations have been studied at the RNA level. In this study we report the RNA molecular characterization of three consensus splice-site mutations identified by DNA analysis in WD patients. One of them, c.51 + 4 A --> T, resides in the consensus sequence of the donor splice site of intron 1; the second, c. 2121 + 3 A --> G, occurred in position + 3 of intron 7; and the c.2447 + 5 G --> A is localized in the consensus sequence of the donor splice site of intron 9. Analysis revealed predominantly abnormal splicing in the samples carrying mutations compared to the normal controls. These results strongly suggest that consensus sequence splice-site mutations result in disease by interfering with the production of the normal WD protein. Our data contribute to understanding the mutational spectrum that affect splicing and improve our capability in WD diagnosis.

Genotype-phenotype correlation in Italian children with Wilson's disease.

BACKGROUND/AIMS: Wilson's disease phenotype is very variable for clinical and laboratory features. Our aim was to assess the role of the type of ATP7B disease causing mutations on Wilson's disease phenotype. METHODS: We retrospectively evaluated the data of children with Wilson's disease from eight pediatric departments. RESULT: Fifty-eight patients (34 male, median age at diagnosis 7.4 years) from 47 unrelated families were studied, carrying 34 different mutations. The most common mutations were the missense p.H1069Q and p.M769V, the nonsense p.R1319X, the frameshift c.2299delC, c.2298_2299insC and c.2530delA, and the splice site mutation c.2447+5G>A. Serum ceruloplasmin and copper were lower among the patients' homozygotes for nonsense and frameshift mutations than in patients with missense mutations. A normalization of serum alanine aminotransferase after therapy was not achieved in 23.6% of patients with missense mutations versus 45.5% of patients with nonsense/frameshift mutations. A direct linear correlation was found between age at diagnosis and urinary copper excretion at diagnosis. CONCLUSIONS: The type of mutation explains at least a part of Wilson's disease phenotype, and mutation analysis should be considered as an integrative tool for such a challenging diagnosis. Urinary copper excretion appears to be correlated to the age at diagnosis rather than genotype.

Steroid therapy for a case of severe drug-induced cholestasis.

OBJECTIVE: To report a severe case of cholestatic liver disease successfully treated with corticosteroids following combined therapy with clarithromycin and nimesulide. CASE SUMMARY: A 15-year-old girl was admitted with cholestasis probably related to treatment with clarithromycin and nimesulide for an upper respiratory tract infection. Other causes of liver disease (infections, metabolic liver disorders, genetic cholestatic syndromes, autoimmune diseases, primary biliary tract disorders) were excluded. Liver biopsy showed a severe canalicular cholestasis with bile plugs in dilated bile canaliculi, giant cell transformation, and portal and lobular infiltrate. An objective causality assessment suggested that cholestasis was probably related to clarithromycin and/or nimesulide use. No benefit was derived from a course of ursodeoxycholic acid therapy. Since the patient experienced a progressive worsening in cholestasis, prednisone was started after 20 days. This therapy was promptly followed by improvement in clinical and laboratory test results. After 2 months of prednisone treatment, the patient became symptom-free with normal liver function tests. DISCUSSION: The manifestations of drug-induced hepatotoxicity are highly variable, ranging from asymptomatic hypertransaminemia to fulminant hepatic failure. No specific treatment for drug-induced hepatotoxicity exists. Early recognition and drug withdrawal are the keys to management of hepatotoxicity, but in some cases, liver disease may persist despite discontinuation of the drug. Possible advantages of corticosteroid therapy have not been well demonstrated. CONCLUSIONS: Application of the Naranjo probability scale indicates a probable relationship between cholestasis and nimesulide plus clarithromycin use. This case draws attention to a possible therapeutic option for some cases of drug-induced hepatotoxicity that show a severe course without any sign of improvement.

Serum transaminases in children with Wilson's disease.

OBJECTIVES: The response of serum transaminase levels to penicillamine and zinc treatment in Wilson's disease is poorly understood. The aim of this multicenter retrospective study was to evaluate transaminase levels after penicillamine and zinc treatment in children with Wilson's disease. PATIENTS AND METHODS: One hundred and nine patients with Wilson's disease (median age at diagnosis, 7.2 years; range, 1 to 18 years), treated for at least 12 months and observed in the last 20 years at 11 Paediatric Departments were studied. Clinical, laboratory and histologic features at diagnosis and initial treatment were recorded. Efficacy parameters were normalization of serum transaminase level and improved clinical and/or laboratory signs. One hundred and two patients had clinical or laboratory signs of liver disease. RESULTS: Fifty-six of 87 patients (64%) given penicillamine normalized serum alanine aminotransferase (ALT) levels within a median of 17 months (range, 2 to 96 months). Of the 29 patients with persistent hyper-ALT, 17 (59%) switched to zinc; only four of these normalized ALT on zinc within a median period of 38 months (range, 7 to 48 months). Eleven (50%) of the 22 patients given zinc alone normalized ALT within a median period of 6 months (range, 1 to 36 months). Of the 11 patients with persistent hyper-ALT, five switched to penicillamine. Three of the five normalized ALT within a median period of 6 months (range, 6 to 9 months). Overall, in penicillamine-treated and zinc-treated patients with persistent hypertransaminasemia, ALT decreased from a basal median of 236 IU/L (range, 54 to 640 IU/L) to a median of 78 (range, 46 to 960 IU/L) at the end of follow-up (P = 0.0245). Poor compliance was suspected in only 10% of cases. No predictive factor of persistent hypertransaminasemia was identified. Liver disease did not worsen in any patient during the study. CONCLUSIONS: Although the efficacy of penicillamine and zinc is well documented, it is notable that a subset of children with Wilson's disease-related liver disease (36%) had hypertransaminasemia despite appropriate treatment with penicillamine or zinc.