London, Oct 2 : A genetic variant believed to be associated with dyslexia can be partly blamed for poor reading ability, according to anew study.
The researchers from University of Oxford have found that people carrying the key sequence tended to perform worse than average in tests of their reading ability, however, there was no impact on general intelligence.
Previous studies have identified at least six candidate genes that appear to affects likelihood of developing dyslexia, a learning difficulty, which affects the development of literacy and language skills.
Out of which, a gene called KIAA0319, which lies on chromosome six was discovered to be the most likely candidate.
Earlier study by Oxford team focussed on the DNA sequence - called a haplotype, which included part of the key gene.
In the current study, the researchers examined the link between this haplotype and reading ability in a sample of 6,000 seven to nine-year old children.
"On average, people carrying this common genetic variant tended to perform poorly on tests of reading ability," BBC quoted Dr Silvia Paracchini, from University of Oxford, as saying.
"However, it's important to note that this is only true for reading ability and not for IQ, so it doesn't appear to be connected to cognitive impairment," she added.
The team has also previously shown that the same haplotype is linked to reduced activity of the KIAA0319 gene during development of the foetus.
This affects development of the cerebral cortex, the area of the brain responsible for thought processes.
In animal studies, switching off KIAA0319 affects neuronal migration, the process that enables nerve cells created in the inner layer of the cerebral cortex area to migrate outwards to their final destination.
"This is clearly only part of the jigsaw puzzle that explains why some people have poorer reading ability than others or develop dyslexia," she said.
"There are likely to be many other contributing factors, but our research provides some valuable clues.
"We need to carry out studies into the exact role that this gene plays in brain development and how this affects people's reading ability," she added.