Humans have approximately 20,000 genes. However, the number of genes varies for each individual (copy-number variation) due to gene increase (gene duplication) or gene loss. This difference in the number of genes is known to be the cause for autism and mental disabilities.
It has been reported that the gene with copy-number variations is present unevenly in the genome but little was known as to the cause.
Assistant Professor Takashi Makino and Professor Masakado Kawata of the Division of Ecology and Evolutionary Biology of the Graduate School of Life Sciences at Tohoku University in collaboration with Professor Aoife McLysaght of the Trinity College at the University of Dublin discovered
that copy-number variations were being suppressed by certain types of gene clusters in its vicinity.
Assistant Professor Makino and his colleagues focused on the gene that occurred in the early evolution of vertebrates in the whole genome duplication known as ohnologs and examined the distance of the ohnologs with other genes in the genome. As a result, it was discovered that genes near the ohnologs tend not to have copy-number variations whereas genes further away from the ohnologs has more copy-number variations.
In particular, copy-number variations were being strongly suppressed in areas of the genome with a high density of ohnologs. It was revealed in these areas, over the course of several million years in vertebrate evolution, exists a gene duplication desert where gene duplication is impossible to occur. The research indicates that the duplication and loss of genome areas including ohnologs is harmful, as it is a cause for death and diseases.
Therefore, the existence of copy-number variations in the gene duplication desert points to the high possibility of diseases. The examination of copy-number variations in these areas is expected to contribute to a possibility for an efficient method to search for disease related genes.
The research results were published in the British science journal Nature Communications on August 6. The paper's title is "Genome-wide deserts for copy number variation in vertebrates."
Assistant Professor Takashi Makino
Graduate School of Life Sciences, Tohoku University
E-mail: tamakino*m.tohoku.ac.jp (Replace * with @)