Biological/Biochemical Features and Molecular Genetics of Specific Language Impairment (SLI)


Common learning disorders include attention‐deficit hyperactivity disorder, dyslexia, specific language impairment (SLI), speech–sound disorder and dyspraxia. They are influenced by genes and several research groups to attempt to identify susceptibility genes of learning disorders through the sequential analysis of genetic linkage and association. This review highlights the genetic contribution to SLI and the current molecular genetic researches aimed at identifying susceptibility and candidate genes for SLI. Currently, four susceptibility loci and three candidate genes (CMIP, ATP2C2 and CNTNAP2) associated with SLI have been found. This review also summarises the biological/biochemical features of SLI. The success of dietary intervention of nutritional supplements (i.e. thiamine and some fatty acids) to improve learning abilities in SLI and dyslexia suggests that a greater understanding of biochemical abnormalities may provide a useful addition with other treatment procedures for these learning disorders.

Key Concepts:

  • Learning disorders may cause the learner to receive and process some information inaccurately. People with learning disorders may have problems of basic psychological processes involved in understanding or in using language, spoken or written, that may manifest itself in an imperfect ability to listen, think, speak, read, write, spell or do mathematical calculations.

  • Individuals with specific language impairment (SLI) seem to have problems in pragmatics, such as discourse maintenance, use and range of speech acts and narrative abilities.

  • Genetic factors are important in specific language impairment.

  • Molecular genetic researches should be aimed to identify susceptibility genes for SLI.

  • Molecular advances in SLI will help to set the research agendas for future studies to follow.

  • The association and linkage studies of learning disorders may help us to understand the biological basis of normal learning variation, and shed light on more fundamental questions regarding the origin of human speech and language.

Keywords: learning disorders; specific language impairment; association; linkage; CMIP; ATP2C2; CNTNAP2


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Further Reading

Caylak E (2009) Neurobiological approaches on brains of children with dyslexia: review. Academic Radiology 16(8): 1003–1024.

Caylak E (2010) The studies about phonological deficit theory in children with developmental dyslexia: review. American Journal of Neuroscience 1(1): 1–12.

Caylak E (2011) The auditory temporal processing deficit theory in children with developmental dyslexia. Journal of Pediatric Neurology 9(2): 151–168.

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Friedmann N and Novogrodsky R (2007) Is the movement deficit in syntactic SLI related to traces or to thematic role transfer? Brain and Language 101(1): 50–63.

Friedmann N and Novogrodsky R (2011) Which questions are most difficult to understand? the comprehension of Wh questions in three subtypes of SLI. Lingua 121(3): 367–382.

van der Lely HKJ, Rosen S and McClelland A (1998) Evidence for a grammar‐specific deficit in children. Current Biology 8(23): 1253–1258.

Newbury DF, Paracchini S, Scerri TS et al. (2011) Investigation of dyslexia and SLI risk variants in reading‐ and language‐impaired subjects. Behavior Genetics 41(1): 90–104.

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Caylak, Emrah(Jul 2011) Biological/Biochemical Features and Molecular Genetics of Specific Language Impairment (SLI). In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0023688]