Medical genetics

The researches find that the The mutation find in the affect child is therefore termed a ‘de novo’ mutation (DNM). “Although many new developmental disorders have been identify in recent years; there are many more to be discover. Identifying them means that we will be able to give an accurate diagnosis to more patients and therefore allow them to have appropriate treatment and care,” Ms Joanna Kaplanis, a Ph.D. student at the Wellcome Sanger Institute, Hinxton, UK; will tell the annual conference of the European Society of Human Genetics today.

The mutation find in the affect

In the largest study to date on developmental delay, the researchers analyzed genomic data from over 31,000 parent-child trios obtained from the UK’s Deciphering Developmental Disorders Project, GeneDx, a U.S.-based genetic testing company; and Radboud University Medical Centre in Netherlands. Analysis of these trios yielded more than 45,000 DNMs.

They developed an improved method to test for the enrichment (over-representation) of damaging DNMs in individual genes. “They found 307 significantly enriched genes; 49 of which are novel. With all of these genes we were able to explain about 51% of the DNM burden in our dataset. We then modeled different underlying genetic scenarios to get an idea of where the remaining de novo burden lies and how we can go about finding it;” says Ms Kaplanis.

Genetic testing company

About 40 percent of developmental disorders are caused by DNMs; equivalent to about one birth in every 295 in the UK alone. The prevalence increases with the age of the parents. The disorders usually become apparent during childhood and include such conditions as autism spectrum disorder, attention deficit hyperactivity disorder (ADHD), intellectual disability, and Rett syndrome.

They may be mild; but in many cases they are severe, and those affected will need lifetime support. However, when they are unidentifiable making a decision on the best care for the affected child is difficult. Given the size of the dataset, the researchers were not surprised to have been able to identify new genes. “However; They are expecting to be able to explain more of the DNM burden than we did.

Developmental disorders

This means that half of the DNM burden in patients with developmental disorders still remains unexplained;” says Ms Kaplanis. “This fact alone gives us clues about where the remaining burden lies and why we do not yet have the capacity to discover the remaining genes.”

A possible explanation is that the DNMs in the genes as yet undiscovered are less penetrant, i.e. they present symptoms in fewer people. “They may need to adapt our system of gene discovery in order to capture these less penetrant genes,” says Ms Kaplanis. ” Incorporating more data from healthy populations may help to try and build a better picture of what they might be.