Washington: It has been found in a recent study that developmental disorders affect certain skills of humans like attention, memory, language, and social interaction.\r\n\r\nThe study was discussed in a meeting 'European Society of Human Genetics annual conference,' Gothenburg, Sweden.\r\n\r\nAlthough many new developmental disorders have been identified in recent years, there are many more which are left undiscovered.\r\n\r\nIn this study, the researchers analyzed genomic data from over 31,000 parent-child trios obtained from the UK's Deciphering Developmental Disorders Project.\r\n\r\nAnalysis of these trios yielded more than 45,000 'de novo' mutation (DNMs). They developed an improved method to test for the enrichment (over-representation) of damaging DNMs in individual genes\r\n.\r\nKaplanis, one of the researchers, said: "We found 307 significantly enriched genes, 49 of which are novel. With all of these genes, we were able to explain about 51 per cent 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."\r\n\r\nAbout 40 per cent of developmental disorders is caused by DNMs, equivalent to about one birth in every 295 in the UK alone. The prevalence of the disease increases with the age of the parents.\r\nThe disorders usually become visible during childhood and include severe diseases such as autism spectrum disorder, attention deficit hyperactivity disorder (ADHD), intellectual disability, and Rett syndrome.\r\n\r\nA possible expectation is that the DNMs in the genes which are as yet undiscovered are less penetrant, i.e., they present symptoms in fewer people.\r\n\r\n"We may need to adapt our system of gene discovery in order to capture these fewer penetrant genes," said Kaplanis.\r\n\r\nThe researchers also hope to increase their sample size in order to try to detect ever more genes associated with developmental disorders.\r\n\r\nHowever, the identification of 40 new genes already provides valuable information to clinicians and to drug developers.\r\n\r\nProfessor Joris Veltman, one of the lead researchers of the study, said: "Developmental delay is often caused by new mutations arising during the formation of sperm or eggs."\r\n\r\n"By combining data on new mutations identified in the DNA of more than 30,000 patients, the scientists could implicate a role for 49 new genes in developmental delay."\r\n\r\n"This study shows the power of large-scale international collaboration to advance our understanding of this disorder and improve diagnostics as well as patient management," added Prof Veltman.