2006 GEP-ISFG collaborative exercise on mtDNA: reflections about interpretation, artefacts, and DNA mixtures

We report the results of the seventh edition of the GEP-ISFG mitochondrial DNA (mtDNA) collaborative exercise. The samples submitted to the participant laboratories were blood stains from a maternity case and simulated forensic samples, including a case of mixture. The success rate for the blood stains was moderate ( approximately 77%); even though four inexperienced laboratories concentrated about one-third of the total errors. A similar success was obtained for the analysis of mixed samples (78.8% for a hair-saliva mixture and 69.2% for a saliva-saliva mixture). Two laboratories also dissected the haplotypes contributing to the saliva-saliva mixture. Most of the errors were due to reading problems and misinterpretation of electropherograms, demonstrating once more that the lack of a solid devised experimental approach is the main cause of error in mtDNA testing.

Diagnosis and staging of bronchogenic carcinoma by transtracheal and transbronchial needle aspiration

Transbronchial needle aspiration (TBNA) has been used in diagnosis and staging of bronchogenic carcinoma. However, its true effectiveness seems uncertain and some models of needles are expensive. The aim of this study was to procure new experiences on this method. TBNA was performed in 194 patients with bronchogenic carcinomas. Two models of cheap, re-usable, cytological needles were used. In diagnostic application, TBNA was positive in 34 of 39 (87%) central tumors and in 31 of 45 (69%) peripheral nodules or masses. In 19 patients, TBNA was the only positive sample. In staging application, TBNA was positive in 41 of the 90 cases (46%) in which the spread of the tumor compressed the wall of the airway. When the trachea or bronchus was endoscopically normal at the site of the puncture, TBNA was only positive in 3 of 20 cases (15%). These results suggest that TBNA is effective as a diagnostic tool. However, it appears to be less effective in staging, where the attainment of a good yield with TBNA probably demands a positive computed tomography and the use of a histological needle.