Novel dystrophin mutations revealed by analysis of dystrophin mRNA: alternative splicing suppresses the phenotypic effect of a nonsense mutation.

The complete dystrophin mRNA sequence has been analyzed in 20 Duchenne muscular dystrophy and Becker muscular dystrophy patients. In 13 cases, deletions in mRNA were detected using reverse transcription-polymerase chain reaction and in another seven cases, point mutations were found using the protein truncation test. Sixteen patients diagnosed with Duchenne muscular dystrophy showed the presence of deletions or of nonsense point mutations. From four patients with the Becker muscular dystrophy phenotype, three cases were associated with deletions conserving the translational frame and one was associated with a nonsense mutation E1110X. In the case of the E1110X mutation, an alternative splicing of dystrophin mRNA (3485-3640del) was detected in this patient which included the E1110X mutation site (nucleotide 3536) and did not change the translation reading frame. Individual nonsense point mutations were characterized by sequence analysis, which showed five novel mutations with respect to those reported in the Cardiff Human Gene Mutation Database http://uwcm.web.cf.ac.uk/uwcm/mg/hgmd0.html and the Leiden muscular dystrophy pages http://www.dmd.nl/.

[Direct DNA diagnosis of Friedreich's ataxia]. / Prímá DNA diagnostika Friedreichovy ataxie.

BACKGROUND: Friedreich's ataxia is an autosomal recessive, neurodegenerative disease with a prevalence of 1-2: 100,000. Ninety five % of cases are caused by Friedreich's ataxia expansion of GAA triplet repeat in the first intron of the X25 gene. The gene is mapped on chromosome 9q. The objective of the investigation was to introduce simple and reliable DNA diagnosis helping to specify of spinocerebellare ataxias. METHODS AND RESULTS: Our diagnosis is based on the differentiation of normal and mutant alleles of gene X25 with PCR and electrophoresis on agarose gel. Size of PCR product of normal allele is in our case 521-614 bp. It is responding to 7-38 GAA triplets. Size of mutant alleles with 200-1200 GAA triplets is as 4100 bp. After the method was introduced, we analysed 12 probands. Four of them suffered from Friedreich's ataxia. CONCLUSIONS: We introduced a fast, non-radioactive, reliable DNA diagnostic method. The contribution of this method is defection of carriers and we can screen of families with the risk of Friedreich's ataxia.

Newer quinolones in the long term prophylaxis of recurrent urinary tract infections (UTI).

Up to 10% of premenopausal women experience recurrent symptomatic urinary tract infection (UTI), mainly due to reinfection from the faecal flora. The recently introduced fluoroquinolones possess a wide spectrum of activity against most uropathogens and achieve high urinary concentrations for extended time periods. Our initial study, conducted between 1993 and 1995, was designed to compare the efficacy and safety of oral pefloxacin 800mg once weekly with oral ciprofloxacin 125mg once daily, over a 12-month prophylactic course in women with recurrent UTI. A 12-month reinfection-free period was achieved in 83.3% of pefloxacin patients and in 78.9% of ciprofloxacin patients. The present study, which commenced in 1996, was designed to compare pefloxacin 400mg with oral fleroxacin 400mg once weekly. Prophylaxis was maintained for 12 months. There are no statistically significant differences between the 2 regimens in terms of efficacy and safety. The most frequently isolated pathogens causing breakthrough reinfections were Escherichia coli and Enterococcus spp. Adverse effects observed were mostly neuropsychic (insomnia) and gastrointestinal. In both studies, there was no evidence of emergence of quinolone-resistant organisms in the urine or rectal flora, even after 12 months of chemoprophylaxis.