Bringing to fruition one of the largest genetic sequencing efforts of a complex disease, an international scientists funded in part identified nine genes on the X chromosome involved in learning difficulties. Their mute leads to mental retardation. The study was published in the journal Nature Genetics.
The mental retardation is defined as the functional deficiency that leads to significant limitations of intellectual functioning and a lack of conceptual, social or practical capacity. Symptoms appear before eighteen years. This type of deficiency is more common in males, and thus it was considered that it was long linked to chromosome X: Because males have one chromosome X, a genetic mutation, which is more likely to have an impact, since they do not have a second to compensate for the mutation.
To learn more about mental retardation linked to chromosome X (XLMR), scientists and partly supported by projects funded GEN2PHEN ( "Genotype-phenotype-to databases: a holistic solution") and EURO-MRX ( "The genetic and neurobiological basis X of-linked mental retardation "), have sequenced about 720 of the 800 genes of known chromosome X in more than 200 households of the United Kingdom, United States, Australia, Europe and South Africa, which had been diagnosed with learning difficulties associated to chromosome X.
Until now, with the help of genetic sequencing techniques, were identified about 80 genes involved nell'XLMR. The discovery of these new genes will contribute to improving clinical practice and advice to families with members suffering from learning difficulties linked to chromosome X.
Dr Lucy Raymond of Cambridge Institute for Medical Research at the University of Cambridge, UK, comments: "This new research reveals yet other genes that can be included to enhance the diagnosis in the case of families with learning difficulties and enable to develop in future a more complete genetic advice, putting the parents and extended family in terms of taking decisions more informed. "
But the study offers further study: "Beyond these important discoveries of new genes associated with learning difficulties, we have discovered a small percentage - just over 1% - gene coding for the protein of the X chromosome, if muted seem to have no effect on the characteristics of the individual, "says prof. Stratton. "It is interesting to note how a number of coding genes can be lost without obvious effects on the normal of an individual: it is a surprising result, and it will be necessary to continue research in this field".
Scientists are launching a warning to geneticists: if the silencing of some genes has no effect observed on the individual, researchers should exercise caution in assuming that the presence of a silenced gene in a patient means there is a relationship between the disease and The gene in question.