British scientists said Wednesday they had discovered 12 genes linked to developmental disorders in children that can cause heart defects, seizures and intellectual disability.
The genes were found in a trawl of the genomes of 1,133 children with severe, undiagnosed disorders and their parents, said the authors of a study published in the journal Nature.
"These newly implicated genes increase by 10 percent the proportion of children that could be diagnosed" by identifying the DNA mutations responsible for their condition, they wrote.
Up to half of children with severe developmental disorders have no specific genetic diagnosis. Some disorders are extremely rare, and symptoms can vary from one person to another.
Pinpointing the genes responsible "is the starting point in the search for new treatments," said a statement from the Wellcome Trust Sanger Institute, which takes part in the ongoing genetic research project dubbed Deciphering Developmental Disorders (DDD).
It may also help doctors understand why some people get developmental disorders, and inform the reproductive choices of people who already have an affected child.
According to the DDD website, some of the most common disorders involve growth problems, physical deformities, and learning and behavioural problems. Symptoms may include epilepsy, autism, schizophrenia, physical deformities or stunted growth.
It is not understood what causes the genetic coding errors that underlie these disorders -- some mutations are inherited from the parents, others appear in the child for the first time.
Most disabilities begin before birth, but some can develop after because of injury, infection, environmental or other factors. The effects can severely impact day-to-day functioning, and may last a lifetime.
The DDD project aims to ultimately analyse genetic data from 12,000 families.
They authors said they would share their findings with other researchers, citing a "moral imperative" to help families in urgent need of diagnoses.
"Researchers hope that the project will inspire more clinical and research programmes around the world to deposit data... to pinpoint more genetic causes of developmental disorders and improve diagnostic rates internationally," said the statement.