"Molecular techniques have become more efficient, increasingly precise and much cheaper, resulting in an unprecedented discovery rate of inherited disease genes. In areas such as primary immunodeficiencies (PID), muscle disorders, growth deficiencies, hearing/vision impairments and metabolic diseases, very large numbers of different genes have been found to carry mutations in diseases with heterogeneous clinical presentation. For example, mutations in almost 150 genes have been found to cause PID. This means that even for well-defined subgroups of PID, mutations in different genes result in identical, or overlapping, phenotypes. Current mutation analysis is very complex, often with many different European laboratories being involved. Thus, individual laboratories carrying out mutation detection normally only cover a few per cent of all disease genes. Obtaining a correct diagnosis is both difficult and time-consuming. If multiple genes need to be analyzed, the cost rises proportionately. New sequencing approaches have been used for the analysis of whole genomes. We will adapt these technologies, based on massive, parallel sequencing, to specific disease fields. This will involve the development of an innovative multiplexing technology. The proposed prototype area is PID, where significant collaboration has already been underway in Europe over the last two decades. We estimate that, using high-throughput sequencing, the cost for analyzing all known 150 PID genes in a single run will be in the same range as the current cost for mutation detection in single disease genes. We will also develop chips to identify single nucleotide polymorphisms (SNPs) for the study of modifier genes. In addition, we will develop reverse-phase protein arrays for proteomics approaches in the diagnostics of PID patients during infancy. During the proposed project we will disseminate information and transfer the developed technologies to other disease areas."