This web page was produced as an assignment for Genetics 677, an undergraduate course at University of Wisconsin: Madison.
What is Dyslexia?
Dyslexia is an inherited language-based learning disability caused by a neurologically-based disorder. Dyslexia can interfere with a person's ability to process language (3,4). This difficulty with language skills would be emphasized mostly in reading, pronouncing words, writing, spelling, handwriting and sometimes arithmetic within a person's life (1,3,4). This often occurs due to problems in in phonological processing, expressive language, and receptive language(4). Dyslexia is referred to as a learning disability (LD) since it can make academic success very difficult to achieve at any level education(4). The severity of dyslexia has varying degrees from person to person.
What Causes Dyslexia?
Dyslexia is often called a neurologically-based disorder because brain and anatomical images show differences in the development and functions in the brain of a dyslexic person as compared to those in the brain of a normal person (4). However, the exact cause(s) of dyslexia are not completely clear. There are many genes that people think may influence dyslexia, these are: KIAA0319, DCDC2, Robo1, and DYX1C1, which are all involved in brain development (2). The gene that this website focuses on is called DCDC2, which studies show may disrupt the normal formation of brain circuits that are necessary for fluent reading, leading to dyslexia that can affect millions of children and adults (1). This gene was identified on human chromosome 6. The genetic alteration that occurs is a deletion within the regulatory region of the gene (1). The DCDC2 gene modulates migration of the neurons within the reading center of the brain where it is expressed (1,2). In order to read normally, the circuits in the brain need to communicate back and forth with each other (1). The alteration that occurs with DCDC2 has been shown to disrupt the development of the brain circuits needed to make reading possible (1). This genetic alteration has been shown to be transmitted within families. However, it should be noted that dyslexia is not caused by lack of intelligence, motivation, desire to learn, inadequate instruction or education, sensory impairment, inadequate instructional, or environmental opportunities (3).
Figure 3. Areas of the brain affect by dyslexia. Figure4. MRI scans of dyslexic brain vs. non-dyslexic brain
Click on images to enlarge
What are the Effects of Dyslexia?
The effect is dependent on the severity of the dyslexia within an individual, and effectiveness of instruction or remediation. It is predicted that the DCDC2 gene is responsible for about 20 percent of cases concerning dyslexia in people (1). In some cases, dyslexics can manage to learn spelling and reading early in life because of excellent instruction, however, later on in life dyslexic individuals can have severe problems with complex language skills like writing essays, grammar, and understanding textbook materials (3,4). These language problems that occur in dyslexic people can be difficult to recognize. This means that problems in school, the workplace, and relationships with people can occur since dyslexia extends beyond the classroom (4). In addition, a person's self-image is affected by dyslexia(4). A person who is a student and has dyslexia can often end up feeling less capable than they actually are and feeling "dumb"(4). Often times the frustration and stress accompanying academic problems will lead students to become discouraged about continuing school(4).
Yale University (2005, October 28). Novel Discovery Of 'DCDC2' Gene Associated With Dyslexia. ScienceDaily. Retrieved February 2, 2009, from
Wang, Y. (2007). The dyslexia susceptibility gene, DCDC2, in neuronal development [Abstract] Retrieved from
WILDD is tax-exempt non-profit organizatio in Madison, WI. WILDD that offers professional reading and spelling
instruction to children and adults (7 and older) with learning disabilities and/or dyslexia. WILDD.3
IDA is a non-profit, scientific, and educational organization dedicated to the study and treatment of the learning disability, dyslexia as well
as related language-based learning differences. The International Dyslexia Association.4
Whos amung us 5
(Figure 1) is from Sonalism. Retrieved on 2/1/09 from http://sonalismrules.files.wordpress.com/2007/12/gemd_02_img00881.jpg
(Figure 2)The Brain Systems for Reading is from Overcoming Dyslexia: A New Complete Science-Based Programs for Reading Problems at
Any Level by Sally Shaywitz. Retrieved on 2/1/09 from http://www.post-gazette.com/pg/07042 /760823-114.stm.
(Figure 3) The Non-impaired Brain / Dyslexic Brain (Images) from Drs. Sally Shaywitz and Bennet Shaywitz New York Times[photograph].
Retrieved on 2/1/09 from http://www.readinghorizons.com/research/dyslexia/brain_images.aspx
( Figure 4)The Pattern and Motion Image Retrieved on 2/1/09 from http://www.lems.brown.edu/~msj/summary/summary.html by
Marc Johannes in Medical Imaging February 1, 2001.
(Figure 5) The Dyslexia Can Affect Image From The Beehive Community Network managed by Northcliffe Media Ltd, Registered in England.
Retrieved on 2/1/09 from http://beehive.thisisnorthscotland.co.uk/default.asp?WCI=SiteHome&ID=5964
Last Updated: 2/2/09