A group of researchers, including Isabel Tejada, a doctor at Cruces hospital in Bizkaia, has discovered three new genes connected with the X chromosome and involved in mental disability. This work, which was published in the scientific journal Nature Genetics, deepens our knowledge about the causes of this hereditary disease and arrives at some important conclusions, among which is the fact that between 30% and 50% of cases of mental disability could be of genetic origin.

Alongside Isabel Tejada, head of the Molecular Genetics laboratory in the Biochemistry Service at Cruces Hospital in Barakaldo (Bizkaia) and president of the Research Group into Mental Disability of Genetic Origin (GIRMOGEN), Francisco Martínez Castellano, researcher in the Genetics unit of the University Hospital La Fe in Valencia, also participated in the project.

This research was carried out by analysing the DNA samples of more than a thousand families from different parts of the world which have transmitted or are transmitting this illness. As a result of this work, the group of scientists was able to find a total of nine new genes involved in mental disability, three of which were described for the first time in this research.

There is also another important revelation amongst the findings in this research work; the existence of many cases of mental disability linked to the X chromosome. According to the research team, this is due to the fact that it passes undetected from mothers to daughters, but appears when passed from mothers to sons.

This study is a team effort led by the Wellcome Trust Sanger Institute in Cambridge (UK), which has had financial input from the Basque Government’s Foundation for Health Innovation and Research (BIOEF) and the Carlos III Health Institute, among other institutions.