Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: FRIDAY, October 14, 1994 TAG: 9410140084
SECTION: NATIONAL/INTERNATIONAL PAGE: A-2 EDITION: METRO
SOURCE: Associated Press
DATELINE: WASHINGTON LENGTH: Medium
Experts said the study, published today in the journal Science, means that children with inherited reading deficits may be diagnosed early enough in life to help relieve problems at the start of formal schooling.
Researchers at four institutions combined data from two groups of reading-disabled people, including sets of fraternal twins, to trace the reading problem to a gene located somewhere in chromosome 6. The study is the first to confirm that a complex trait like a reading disorder can be genetically linked.
``We have now narrowed it to a very small part of the human genome,'' said John DeFries, senior author of the paper and a senior scientist at the Institute for Behavioral Genetics at the University of Colorado in Boulder. ``It now should be much easier to find the actual gene.''
Reid Lyon, a director of research on learning disabilities at the National Institute of Child Health and Human Development, said that the discovery by DeFries and his colleagues ``is significant because it could lead to identifying children early who have this reading difficulty.''
Lyon said that about 20 percent of all children are born with dyslexia, a condition that commonly includes the inability to distinguish separate parts of a word, an important skill in learning to read.
``These kids can't chop words into the different sounds or parts, and it makes it a terrible task for them to learn to read,'' he said. Many never overcome the problem.
``Generally, there's no intervention for a student with dyslexia until about the third grade,'' Lyon said. ``If schools wait until then, 70 [percent] to 80 percent will have the problem for the rest of their lives. We're losing millions of kids by waiting until the third grade.''
Earlier training, starting at about age 5, can increase success to about 50 percent, he said, but a diagnosis at 1 or 2 years old could be even better.
DeFries said the genetic studies, done at the University of Colorado with 50 pairs of fraternal twins, were combined with a study of 19 families at the Center for Hereditary Communications Disorders in Omaha.
All of the study subjects had average or higher intelligence but still had some type of reading disorder. The twins were ages 8 to 20, and the families studied stretched over three generations, he said. The twin study included one twin with reading problems and one without.
By comparing genes in blood samples taken from the reading-disabled group with genes taken from people without such problems, the researchers were able to link an abnormality in a segment of chromosome 6 to the reading problem.
Lon R. Cardon, a co-author of the study and now a researcher at Stanford University, said the suspected fragment of chromosome 6 has been identified as containing genes that contribute to hay fever, migraine headaches, asthma, thyroid disease and allergies.
``An earlier study has shown that children with dyslexia have a higher rate of these disorders,'' Cardon said.
by CNB