Tayfun Özçelİk, M.D., Ph.D.
Tayfun Özçelik is a professor of human genetics at Bilkent University. He is a graduate of Istanbul Medical School. He completed his post-graduate education at Yale and Stanford Universities. His research focuses on the identification of genes that lead to complex phenotypes in humans. Since 2012, he collaborates with investigators at Rockefeller University to study extreme obesity and sleep disorders in consanguineous families. Through mapping studies on human and mouse chromosomes, he identified the genes for Prader-Willi syndrome and Charcot-Marie-Tooth disease Type IA. His group defined the molecular basis of cerebellar hypoplasia associated with quadrupedal gait in humans, and contributed to the identification of causal gene mutations in circadian clock gene CRY1 and delayed sleep phase disorder. He contributed to collaborative genomics studies for human health and cooperation in the Mediterranean region, and pioneered the application of genomic sequencing methods in DNA-based diagnostics including forensics in Turkey. He is a member of the Turkish Academy of Sciences, and served as the board member and education committee chair of the European Society of Human Genetics, program committee member of the American Society of Human Genetics, and president of the Turkish Society of Medical Genetics. He received the TÜBİTAK Science Award in 2012.
Characterization of the genetic structure of Turkey reveals a high level of admixture
We investigated the genetic structure of Turkey from 3,599 unrelated subjects who have been whole-exome (n = 2,826) and wholegenome (n = 773) sequenced. We observed a high level of admixture consistent with ancient DNA studies. Present-day Turkey has three distinct Anatolian ancestries and six 1000 Genome population contributions from Africa, Europe, South Asia and East Asia. Almost all Turkish individuals have the contribution of all ancestries in their genomes. Treemix analysis revealed that Turkey serves as a crossroad between Middle Eastern and European populations. Wright’s fixation index and principal component analysis was consistent with a close relationship of the Turkish population with European populations. Since the Turkish population, as well as other populations with high consanguinity contribute substantially to the identification of Mendelian phenotypes, we characterized inbreeding status and length of runs of homozygosity. We uncovered a significant number of individuals with very high inbreeding coefficients and increased burden of long runs of homozygosity. Derived allele frequency calculations showed that approximately 30% of exome and 50% of genome variants in the very rare range are unique to the Turkish Variome. In conclusion, our results indicate a high level of admixture in the Anatolian peninsula, and the variation specific to the Turkish population is a valuable resource for disease gene identification studies.