ABO genotyping proficiency testing: methodological strengths and outstanding issues requiring consideration.

Development of proficiency testing (PT) for ABO genotyping is of great importance for the purpose of standardization and quality control in transplantation and histocompatibility laboratories. Hod-Dvorai et al. offer an interesting experience, describing a graded PT scheme that was developed and realized within a few years. The use of independently characterized materials for selected surveys may allow distinguishing between analytical errors and methodological trends, while the increase of allele diversity would contribute to the relevance of PT. These changes might improve the precision of grading and, indeed, participants feedback, thus further developing the framework suggested by the authors of the article.