Scientists find the cause of severe mental retardation

Release date: 2014-06-17

Recently, a study published in Nature said that whole-genome sequencing can diagnose severe mental retardation, but these patients are negative in other tests. Severe mental retardation occurs in 0.5% of newborns and has a different genetic background, which means that the cause of this disorder is generally unknown. The study found specific abnormalities on DNA that may be the main cause of severe mental retardation.

Gene chip research and exon sequencing generally focus on selected genes or DNA fragments that identify genetic defects that are not from parents, including changes in gene structure and sequence. Despite this information, most of the cases of severe mental retardation remain undiagnosed.

To investigate the wide-ranging genetic variation of this diverse disease, Joris Veltman and the research team at the University of Mejän University in the Netherlands performed genome-wide sequencing of 50 patients with severe mental retardation and their parents without mental retardation.

Previous genetic screening in these patients did not reveal any disease gene markers, but this analysis found 84 new sequence changes (single nucleotide variation, SNVs for short) and 8 new structural variations (copy number) Mutations referred to as CNVs are associated with severe mental retardation. The whole genome sequencing method successfully diagnosed 42% of the patients in the study.

The results of these studies suggest that the effects of nascent SNVs and CNVs mutations on the coding region DNA are an important cause of severe mental disability and highlight the value of whole-genome sequencing as a tool for the diagnosis of severe mental retardation, the researchers said.

Source: Chinese Academy of Sciences