Texas Education Code (TEC) §38.003 defines dyslexia and related disorders in the following way:
“Dyslexia” means a disorder of constitutional origin manifested by a difficulty in learning to read, write, or spell, despite conventional instruction, adequate intelligence, and sociocultural opportunity. Related disorders include disorders similar to or related to dyslexia such as developmental auditory imperceptions, dysphasia, specific developmental dyslexia, developmental dysgraphia, and developmental spelling disorder.

The International Dyslexia Association defines “dyslexia” in the following way:
Dyslexia is a specific learning disability that is neurobiological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede the growth of vocabulary and background knowledge. Adopted by the International Dyslexia Association Board of Directors, November 12, 2002.

Students identified as having dyslexia typically experience primary difficulties in phonological awareness, including phonemic awareness and manipulation, single-word reading, reading fluency, and spelling. Consequences may include difficulties in reading comprehension and/or written expression. These difficulties in phonological awareness are unexpected for the student’s age and educational level and are not primarily the result of language difference factors. Additionally, there is often a family history of similar difficulties.

The following are the primary reading/spelling characteristics of dyslexia:

• Difficulty reading words in isolation
• Difficulty accurately decoding unfamiliar words
• Difficulty with oral reading (slow, inaccurate, or labored without prosody)
• Difficulty spelling

It is important to note that individuals demonstrate differences in the degree of impairment and may not exhibit all the characteristics listed above.

The reading/spelling characteristics are most often associated with the following:

• Segmenting, blending, and manipulating sounds in words (phonemic awareness)
• Learning the names of letters and their associated sounds
• Holding information about sounds and words in memory (phonological memory)
• Rapidly recalling the names of familiar objects, colors, or letters of the alphabet (rapid naming)

Consequences of dyslexia may include the following:

• Variable difficulty with aspects of reading comprehension
• Variable difficulty with aspects of written language
• Limited vocabulary growth due to reduced reading experiences

(Adopted from "The Dyslexia Handbook", TEA, Rev. November 2018)

• TEA Dyslexia Handbook & Resources
• TEA - Dyslexia Fact Sheet