I chose this topic for my paper because someone who I am close to has severe dyslexia. I wanted to write about this topic in order to gain some understanding about the disorder, and to try and understand the struggles that a person with dyslexia has to go through in order to learn, especially when it comes to reading and writing. I was especially interested in learning what causes dyslexia.

The Society for Neuroscience (SFN) defines dyslexia as a reading disability that is marked by deficits in the decoding of words. The symptoms of dyslexia include difficulty in spelling, recognizing sounds in words, processing rapid visual information, and saying words quickly.

Recently, scientists have been trying to identify any particular part of the brain that might be responsible for dyslexia, by taking pictures of the brain at work in dyslexics. The angular gyrus (AG) is a part of the brain that has repeatedly shown up in scans as being the part of the brain that is active while a person is reading. Scientists have identified the AG as the part of the brain that translates letters into language that we understand. Recent research has shown that in dyslexics, there is less activity in the AG than with non-dyslexics, which leads scientists to believe that in dyslexics the AG does not work normally (SFN, 1999).

Researchers have done studies on the heritability of dyslexia, and whether it can be passed down genetically from parent to child. Scientists have looked at families with dyslexia and found that only about 5% of children whose parents read normally have a reading disability. On the other hand, the percentage of affected children with one or both parents who suffer from dyslexia is much higher. A study of children who have one or two dyslexic parents found that by the second grade, 31% of the children are identified as dyslexic by their school. When the same sample of children was tested using research equipment, the number was 61% (Grigorenko & Wood, 2001). These results suggest the possibility that dyslexia is genetic.

However, while dyslexia does seem to have a genetic basis, the environmental influences on a child also warrant examination. A study by Davis, Knopik, Wadsworth and DeFries, cited by Grigorenko and Wood, 2001, showed that a child’s risk for having dyslexia also depends upon the reading skills of the parent. This is because the environment that a child is raised in will also affect their reading development, so if they are raised by parents who have difficulty reading, it is more likely just by environmental influence that the child will also have difficulty reading. Therefore, an adult dyslexic who has learned to compensate for the disorder is less likely to raise a child with the same disability than an adult dyslexic who has not learned to compensate for the disorder is.

Further research has been done to find a possible genetic cause of dyslexia, and progress is being made in tracing the disorder to a specific gene. In a 1991 study of twins, a link was found between dyslexia and chromosome 6p21.3 (Smith et. al., 2001). There is a gene called the myelin oligodendrocyte glycoprotein gene, or the MOG gene, that is located on that region of the sixth chromosome, which is associated with reading skills. Based on several studies, researchers selected the MOG gene for study as a possible causal gene for dyslexia. The studies that led researchers to choose the MOG gene for further examination included a 1994 study which showed that there was a relationship between intelligence and a marker that is found near the MOG gene. The studies that have been done on the MOG gene showed that although the gene is located in the area that has been identified as the reading disability locus, it is itself probably not the causal gene for dyslexia. However, the study results show that the MOG gene is close to the causal mutation that causes reading disability, so perhaps soon researchers will be able to identify a specific genetic mutation that is the cause of dyslexia (Smith et. al., 2001).

There is also a theory that antibodies from the mother could cross the placenta and enter the fetus during pregnancy to cause dyslexia. Scientists think that this would especially be the case with women who have given birth to more than one child with the disorder, which in itself suggests that there is a genetic basis for the disorder. Vincent et. al. (2002) conducted a study in which they injected pregnant mice with serum taken from women who had given birth to two or more dyslexic children, and then they tested the offspring of the mice for behavior problems and brain defects. The control group in this experiment was injecting mice with serum from women with no dyslexic children, and from women who were pregnant for the first time. The results showed that the offspring who had received the serum of one particular woman, known as Dys-M1, who had two dyslexic children and who had also had several miscarriages, showed abnormal levels of cerebellar choline and creatine levels, as well as deficiencies in motor development. Among the other mice who had received serum from the women with dyslexic children, several had spontaneous abortions of their litters, and the remaining full-term litters were okay. One interesting result was that most of the spontaneous abortions happened in four mice that had all received serum from two particular women in the study, Dys-M4 and Dys-M5. The litters born to the mice in the control group were mostly okay. While this study is only a preliminary study and offered no conclusive results, the results did suggest that some symptoms of dyslexia could result from maternal antibodies. One suggestion was that the antibodies that seem to cause dyslexia might stimulate miscarriages in some cases, but if a miscarriage does not occur then the child will have dyslexia or other neurological disorders (Vincent et. al., 2002).

Research into the cause of dyslexia is still a new concept, so new ideas and possibilities for what causes the disability are always being suggested. The general assumption seems to be that dyslexia is genetic and is influenced by upbringing. Meaning that if a child with a genetic predisposition to dyslexia is born to two non-dyslexic parents, the child is less likely to develop dyslexia than would be a child who was predisposed to dyslexia and was raised by one or both dyslexic parents. There are still a lot of unanswered questions about the exact origins of dyslexia, but scientists seem to be coming closer and closer to identifying exactly where the disorder originates.

While doing the research for this paper, I was surprised to find out that scientists have been able to pinpoint an area on the sixth chromosome that is associated with reading skills and comprehension. A chromosome is such a small thing, and to be able to place something like reading skills onto something as tiny as the sixth chromosome shows me that we have had amazing advances in medical technology. I would really like to find out more as researchers come closer to finding out where dyslexia comes from, and as they even possibly are able to develop a cure for the disorder.

Researching for this paper has better helped me to understand the difficulties that dyslexic people face in school, work, and any daily situation that involves the processing of language. I also feel more prepared by doing this research to enter into the job I want, which is working with behaviorally challenging adolescents. Now I have more understanding into how frustrating having a learning disorder such as dyslexia must be, and maybe all that some teenagers who have been labeled “difficult” need is a unique style of learning because they have a disorder that prevents them from learning the way that other people do.

Grigorenko, E. and Wood, F. (2001) Emerging issues in the genetics of dyslexia: a methodological preview. Journal of Learning Disabilities, Vol. 34, Issue 6.