Asian Scientist (Jul. 2, 2013) – An international team of researchers have identified a gene deletion associated with brain changes and delayed language acquisition in children of Southeast Asian descent.
In their study, published in the American Journal of Human Genetics, the researchers found that deletion of a portion of a gene known as TM4SF20 is associated with expressive language delay and brain changes in children. Intriguingly, this genetic change is common in children from Southeast Asia or with ancestral connections to the region.
“I got intrigued when I kept seeing this small (genomic) change in children from a large sample of more than 15,000 children,” said Dr Seema R. Lalani, a leader of the study.
“These children were predominantly Burmese refugees or of Vietnamese ancestry living in the United States.”
Dr Lalani soon realized that there was a pattern of early language delay and brain imaging abnormalities in the children who carried this abnormality. Within a period of two to three years, the researchers found 13 more families with similar problems and having the same genetic change.
Language delays mean that they may speak only two or three words at age 2, in comparison to other children who would generally have between 75-100 word vocabulary by this age. However, the researchers found that many such children who can be described as late-talkers may overcome early speech and language difficulties as they grow.
According to the researchers, the genetic change is present in 2 percent of the Vietnamese Kinh population (an ethnic group that makes up 90 percent of the population in Vietnam). However, the genetic abnormality can be found in children who are Vietnamese, Burmese, Thai, Indonesian, Filipino and Micronesian as well.
Because these are all within a geographic location, Dr Lalani suspects that there is an ancient founder effect, meaning that at some point in the distant past, the gene deletion occurred spontaneously in an individual, who then passed it on to his or her children and to succeeding generations.
Source: Baylor College of Medicine; Photo: linh.ngan/Flickr.
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