The identification of novel mutations in the biotinidase gene using denaturing high pressure liquid chromatography (dHPLC).

Biotinidase deficiency (BD) is an autosomal recessive disorder of biotin metabolism that causes incomplete recycling of free biotin. The resulting depletion of intracellular biotin leads to impaired activities of biotin-dependent carboxylases. The ensuing clinical phenotype includes progressive neurologic deterioration with epileptic seizures, muscular hypotonia as well as skin eczema. BD may be readily diagnosed by analysing enzyme activity in dried blood spots during newborn screening but typically requires molecular confirmation. More than 100 different mutations in the biotinidase gene have been reported to date. To simplify molecular testing we have developed a rapid and accurate denaturing high pressure liquid chromatography (dHPLC) method of the promoter, 3'UTR, all exons including exon/intron boundaries as a first line screen followed by direct sequencing of the respective PCR products. To validate this method we used DNA from 23 different, newly diagnosed patients with biochemically proven BD from Austria, India, Morocco and Spain. A total of 11 mutations, missense 7, frameshift 3 and 1 nonsense, were screened. Six mutations were novel to this study. All mutations revealed distinct dHPLC pattern thus enabling their accurate detection. This study revealed that dHPLC method is robust, automated, economical and above all highly sensitive for the molecular analysis of biotinidase gene and should be used as a pre-analytical tool followed by sequencing of aberrant heteroduplex forming amplicons.

Lung cancer symptoms at diagnosis: results of a nationwide registry study.

BACKGROUND: Lung cancer is currently the leading cause of cancer death. Despite its high incidence and mortality, there are few studies describing its symptoms at diagnosis broken down by tumour stage and tobacco use. Accordingly, this study was proposed to describe the frequency of the most common symptoms of non-small cell lung cancer and small cell lung cancer (SCLC) at diagnosis, with a breakdown by stage and tobacco use. PATIENTS AND METHODS: Cases were collected from the Spanish Thoracic Tumour Registry, a nationwide registry sponsored by the Spanish Lung Cancer Group. More than 50 hospitals recruited histologically confirmed lung cancer cases and information was gathered through personal interview plus data contained in the electronic clinical record. There were no data available on the lag between the appearance of the first symptoms and diagnosis of lung cancer. RESULTS: A total of 9876 patients (74% male, median age 64 years) were recruited from 2016 to 2019. Of these, 12.5% presented with SCLC. Stage IV was the most frequent stage at diagnosis (46.6%), and the most frequent symptom was cough (33.9%), followed by dyspnoea (26.7%). No symptom was present in 59% of patients diagnosed in stage I; 40% of stage I patients presented with at least one symptom, while 27.7% of patients in stage IV had no symptoms at diagnosis. Cough was the most frequent symptom in SCLC (40.6%), followed by dyspnoea (34.3%). The number of symptoms was similar across the respective smoking categories in SCLC, and differences between the symptoms analysed did not exceed 7% in any case. CONCLUSION: The absence of the most frequent symptoms (ie, cough, pain, dyspnoea) should not lead to a decision to rule out the presence of lung cancer. A relevant percentage of stage IV patients displayed no symptoms at diagnosis.