Acknowledgements
This study was supported by the Latvian Council of Science, Grant 10.0010. We thank the Genome Database of the Latvian Population and the Latvian Biomedical Research and Study Centre for providing data and DNA samples.L. Nikitina-Zake was supported by ESF grant 1DP/1.1.1.2.0/09/APIA/VIAA/150.