Mutations on the GNPTAB, GNPTG, and NAGPA have been found to disrupt the signal that directs enzymes to target locations in the brain and cause stuttering in vocal and linguistic processes. Cluttering
Cluttering (Tachyphemia) is a fluency disorder that can co-occur with stuttering but may also occur individually. When someone is experiencing cluttering disorder their conversation segments may be perceived as too fast, too irregular or both. Other symptoms may include stuttering, language or phonological errors, and attention deficits. It may result from disorganized speech planning or being unsure of what to say. Both cluttering and stuttering are forms of fluency disorders that develop beyond the key years of about ages 2–6. During these ages, dysfluency is mainly just considered to be developmental dysfluency. Cluttering, unlike stuttering, can be distinguished by little to no physical structure, little to no secondary behaviors, decreased awareness of speech problems and the aforementioned typical dysfluencies such as revisions and interjections. Both stuttering and cluttering both have a genetic component. About 1/3 of those who stutter will also clutter which can prove even more difficult to overcome with Speech therapy. A consequence of cluttering is individuals may not be willing to attempt to repair breakdowns in communication which may result in less effective social integration and interactions that can lead to a sense of isolation, anxiety, and depression. Differences between disorders and developmental dysfluency
There are several warning signs of speech delays that are not considered developmentally normal.
Developmental dysfluency, or "normal dysfluency", is a lack of language fluency that occurs during early childhood development. It is commonly observed in children ages 2 to 4 years old. This typically occurs as they begin to learn language and communication skills. Developmental dysfluency refers to speech that is continually interrupted rather than flowing naturally. Developmental dysfluency is most commonly expressed through inconsistencies in speech such as stuttering, repetition, lengthening of sounds and syllables, mistiming, and poor inflection.Speech is a complicated skill involving a series of cognitive and linguistic processes that are both sensorimotor and auditory. As children grow, their language and vocabulary grow exponentially. Dysfluencies in early speech are typical as their speech skills develop. The most common form of dysfluency in children younger than three years is the repetition of one-syllable words or parts of words. Words or syllables are often repeated in the beginning of their sentences as they try to process how to form the rest of the sentence. Language dysfluency may be common in children as they learn basic language skills throughout the crucial development stages in early childhood. Developmental dysfluency is normal in children as they work to acquire language skills and semantic/syntactic processing. About twenty-five percent of children experience some loss in fluency in their linguistic abilities. Some children between the ages of 2 and 6 encounter some obstacles in the path to fluent speech. Fluency in a normal child will typically improve around the age of 4. When attempting to master spoken language, children gradually develop fluent speech.