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Genetic Test for Dyslexia

According to the National Institute of Neurological Disorders and Stroke, dyslexia affects as much as 10 to 17 percent of the United States population, with nearly 50 percent of children born to dyslexic parents inheriting the condition. Similar numbers appear in other countries that speak different languages. A genetic test for dyslexia looks at the genes that code for language and visual processing and then looks for mutations within these genes.

  1. Dyslexia

    • Dyslexia disorders appears most prominently within a person’s ability to recognize words. Difficulties in recognizing word forms can result in impaired reading abilities; however, a person’s overall intelligence can be normal or even above normal with dyslexic conditions. In effect, dyslexia's effects on the brain target regions that carry out visual processing and comprehension skills. According to the National Institute of Neurological Disorders and Stroke, these factors point to a genetic cause for dyslexia as opposed to an environmental cause.

    Brain Processes

    • According to LDOnline, a learning disabilities resource site, difficulties with identifying words and sounding them out, or decoding, accounts for the reading problems encountered by dyslexic individuals. Decoding tasks require the brain to make letter-sound associations while orienting words within the context of the text. Difficulties with word identification result in the disorientation encountered when trying to identify letters. These difficulties indicate a malfunction within the brain circuitry processes that relate letters with sounds. According to the National Institute of Neurological Disorders and Stroke, these malfunctions arise from a genetic component, which can be identified and tested for.

    Genetic Variations

    • According to the National Institute of Neurological Disorders and Stroke, a study conducted in 2005 by the Yale University School of Medicine identified a key genetic factor associated with dyslexia. A gene classified as DCDC2 was found to alter the brain circuits involved in reading processes. Genetic tests for dyslexia show a series of possible variations associated with how DCDC2 genes affect reading and comprehension abilities. These variations may account for how some people have difficulties with letters and words, while others have trouble with letters and numbers.

    Neural Processing

    • The genetic study conducted by Yale University also examined the effects of DCDC2 gene variations on neuronal patterns within the brain. Using embryonic rats, researchers altered how this gene codes for neuronal patterns within the brain, according to the National Institute of Neurological Disorders and Stroke. DCDC2 was found to regulate neural processing mechanisms within the brain. When altered, neural impulses were unable to reach their target destinations, resulting in delayed reflexes in newborn specimens. Because DCDC2 appears within human genetic code, researchers were able to observe similar delays within the neural circuitry of dyslexic individuals.

    Universal Gene Trait

    • Genetic tests for dyslexia were conducted in 2006 at the University of Bonn in Bonn, Germany, through an independent study that also established a relationship between the DCDC2 gene and dyslexia symptoms, according to the National Institute of Neurological Disorders and Stroke. Subjects were given the same types of reading tests used at Yale University using German language texts. Results from this study helped to establish a universal source of origin for dyslexia within the human gene pool, because gene effects appear to cross language differences.

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