Biobanks and the importance of detailed phenotyping: a case study--the European Glaucoma Society GlaucoGENE project.

BACKGROUND: Dissecting complex diseases has become an attainable goal through large-scale collaborative projects under the term "biobanks." However, large sample size alone is no guarantee of a reliable genetic association study, and the genetic epidemiology of complex diseases still has many challenges to face. Among these, issues such as genotyping errors and population stratification have been previously highlighted. However, comparatively little attention has been given to accurate phenotyping. Study procedures of existing large-scale biobanks are usually restricted to very basic physical measurements and non-standardised phenotyping, based on routine medical records and health registry systems. DISCUSSION: Study procedures of existing large-scale biobanks are usually restricted. Considering that the objective of an association study is to establish genotype-phenotype correlations, it is doubtful how easily this could be achieved in the absence of accurate and reliable phenotype description. The use of non-specific or poorly defined phenotypes may partly explain the limited progress so far in glaucoma complex genetics. This report examines the European Glaucoma Society GlaucoGENE project, which is the only large multicentre glaucoma-specific biobank. Unlike previous biorepositories, this initiative focuses on detailed and standardised phenotyping and is expected to become a major resource for future studies on glaucoma.