Introduction

In search of clinically relevant genetic risk factors for common disorders, genome-wide association studies (GWAS) have been performed since more than

15 years, with meagre results. Now even the most prominent advocate of this research direction has thrown the sponge1  and world-wide, rare disorders have come into focus of genome research again2. We were among the first to point out the inherent difficulties of GWAS in complex diseases, including their genetic heterogeneity, and to stress the importance of studying single gene disorders as a better alternative. Consequently, the research of our department has revolved around monogenic disorders since its inception3.

During the past decade, we have increasingly focused on intellectual disability (ID) and related disorders. ID, also called mental retardation or early-onset cognitive impairment, is the biggest unsolved problem of clinical genetics and a far heavier socio-economic burden than, e.g., cancer4. Of the several thousand gene defects that may give rise to ID, only a few hundred have been identified so far, since many forms of ID are clinically indistinguishable and because in Western Societies, families tend to be small. We circumvented this problem by forging international cooperations, e.g. with a potent group in Iran. This enabled us to study familial forms of ID in a systematic manner, and put us in an excellent position for scaling up this research when high-throughput sequencing techniques became available, as outlined below.

This research would not have been possible without substantial financial support from the Max Planck Society and additional funding from the German Federal Ministry of Education and Research. Both came to an end in October 2011, when the Head of the Department reached his official retirement age, but was re-installed as Acting Director for a period of three years. Since then, a deconstruction plan is in place, which entails a progressive reduction of the structural budget until the end of October 2014, when the department will be closed. However, additional financial support has been obtained through an EU grant (Genetic and Epigenetic Networks in COgnitive DISorders [GENCODYS], FP7 reference no. 241995,

05/2010 – 04/2015) which will partially compensate the diminishing structural resources.

In accordance with the deconstruction plan, the groups of Tim Hucho (Signal Transduction in Pain and Mental Retardation) and Diego Walther (Monoamine Signalling and Disease, Mouse Lab.) were discontinued when the contracts of their leaders expired. Andreas Tzschach, our former clinical geneticist, left for the University of Tuebingen in 2011, and his position was filled by Thomas Wienker, a human geneticist and retired professor of biostatistics from the University of Bonn. Andreas Kuss was appointed as a professor (W2) by the University of Greifswald, and since 2011, Luciana Musante, a former post-doctoral fellow in the group of Vera Kalscheuer, is now in charge of our research into recessive ID. While we are still maintaining close ties with Wei Chen, now at the Max Delbrück Center in Berlin, his part-time appointment at the MPIMG was discontinued in 2011, and his former post-doctoral fellow Hao Hu took over his task as the bioinformatician of our department. Finally, the part-time appointment of Susann Schweiger (University of Dundee and future Head of Human Genetics at the University of Mainz) has also been terminated in 2011.

In view of the reduced size of the department, which is also due to the fact that we can no longer hire PhD students, most former groups have lost their critical mass. At the same time, the research of the remaining scientists converged and their collaboration intensified. Therefore, their scientific achievements are no longer presented separately, except for Tim Hucho, recently appointed as W2 professor at the University of Cologne, and Reinhard Ullmann’s group with its gradually diverging orientation and own DFG support.