Study at Ontario Science Centre explores how reading ability is influenced by genetic and environmental factors

A project of The Hospital for Sick Children, the Canadian Language and Literacy Network, and the Ontario Science Centre

Objectives

The ability to read is related to a number of overlapping skills. These skills can be tested and give a good indication of a person's reading ability.  One skill, decoding, is the ability to understand the relationship between written symbols and speech sounds. This can be tested by seeing how fast someone can correctly pronounce pretend words that sound like real words but do not exist in a particular language. Another skill is rapid naming; the ability to quickly name familiar visual symbols such as letters, numbers, colours, and objects. This ability can be measured using a task, Rapid Automatized Naming (RAN), which requires people to name items presented to them as quickly and as accurately as possible. 

Research suggests these skills and reading ability are influenced by both genetic and environmental factors. Thus far studies of families with reading disabilities (also called dyslexia) indicate that there are at least 10 genes located in different chromosomes that contribute to reading disabilities. The same genes likely contribute to reading ability in the general population. The location of these genes within the chromosomes is known and the genes are currently being identified.  Our goal in this study is to identify specific genes that may play a role in reading ability and specific reading skills.

Methods

A total of 1,047 visitors (393 families) to the Ontario Science Centre participated in this study.  Parents that participated completed three questionnaires: one about their child's attentiveness and ability to concentrate, a standard demographic questionnaire and a questionnaire about how much a child is read to as well as how much reading each child does on their own. 

The children, aged 6 to 16 years, completed a series of computer tasks where response time (time to make decision) and accuracy (whether right or wrong) were measured. The children also completed several short word games on paper. These tests have been proven to provide a good indication of reading ability. 

The tasks completed were:

• A test where the children chose which of two pretend words is more like a real English word
• Word tests to see how fast the children could say real words and pretend words
• Tests of how quickly the children could name a list of letters, objects, numbers & colours

For the genetic study, a cheek swab sample was collected from all 1,047 individuals that participated. From the cheek swabs, we were able to isolate DNA, the genetic material, for each person.  We will be able to compare the scores on the tests and the variations in each person's DNA to, hopefully, identify genes that are involved in the reading process.

Preliminary Results

We first wanted to get a general idea about the children and families that participated. First, we saw that almost the same number of boys and girls participated, with just 32 more girls than boys participating. We also saw that the majority of children were between 9 and 12 years of age.

The children in our study were required to have English as a first language or were required to have at least 5 years of education in an English speaking school. Of the children that spoke two languages, the most common was Cantonese (2%) or Mandarin (2%) with a total of 32 different languages reported. We looked to see if children having English as a first language in the home were better at the word games. We found that children that spoke English at home had very similar word skills as those that had learned English as a second language but had been in an English school for at least 5 years.

We also looked at the average scores for the tests of real and pretend word reading for all of the children and we found that they were slightly above the average for children their age. The average score is around 100 of a possible 145. However, there was a wide range of scores.  Children with both good reading skills and poor reading skills participated. These results indicate that we have achieved our goal of collecting a sample of families that reflect the reading ability in the general population. 

We began this study by looking at one specific gene that is suspected to be involved in reading skill ability. This gene is located on chromosome 1p and was chosen because it is very similar to a gene on chromosome 6p that is suspected to contribute to reading disability. We have already looked at DNA variations in this gene on 1p in a sample of families with reading disabilities and found evidence that it could contribute to a person's ability to read. The function of this gene is unknown but the related gene on 6p appears to be involved in guiding the nerve cells to their proper location during brain development.

We looked at the relationship of this 1p gene to how the genes were passed from the parents to the children and their scores on naming pretend and real words. To do this, we looked at the five different DNA changes in the gene and looked for a correlation to the reading measures. For the DNA changes we looked at, we found no evidence for a relationship to the reading measures. This could mean that this gene is not related to reading ability, however, we need to study this gene further before final conclusions are made.

Future Steps

Thus far we have only looked at one gene and we will begin to examine some of the other genes suspected to be involved in the reading process. 

Acknowledgements

We would like to thank the staff of the Ontario Science Centre for the opportunity to carry out this study at the Centre and the excellent help from staff and hosts.  We also thank our grant sponsor the Canadian Language and Literacy Network

We cannot thank you enough for your participation in this study. We hope this letter provides you with some interesting details about your specific contribution to research conducted by scientists associated with SickKids and the Canadian Language and Literacy Research Network and the advancement of scientific knowledge, particularly in the field of reading research.

More info on the study here.

Any further questions can be addressed to our email account at oscjuly2006@yahoo.ca