Friday, 6 April 2012

Speech and Language Disorders

Speech and Language Disorders 

We are probably aware of the fact that speech and language disorder start at early stage in our life, but many of us do not realize the genetics factors that play a major role in controlling our speech and language behavior. These disorders are either developed or acquired following a neurological injury but many researchers believe they are inherited. They also believe that early stages of speech and language impairments are vital symptoms for global condition such as autism, hearing and learning disability. Speech and language deficits vary and difficult to be classified into distinct categories. The can be simply as impairment in production of fluent and comprehensive speech to more specific one such as verbal dyspraxia which involve impairment in the coordination and motor control of the speech organs (Newbury & Monaco 2010). Moreover, many argue that the relationship between speech and language deficits is uncertain or weak and remains a matter of debate (Newbury & Monaco 2010). 

Based on old studies, scientists are certain that genetics factors contribute to susceptibility to speech and language impairments. The use of genome-wide linkage or association (GWL/A) studies, the well-known biological method helped in identifying three major genes that contribute to speech and language disorders among several people (Newbury & Monaco 2010). The association method briefly looks for SNPs variants between two groups of people where one group has the disease and the other is healthy (National Institutes of Health 2011). The most frequent genetics variants in the diseased group is said to be associated with the disease (National Institutes of Health 2011). In contrast, the genome-wide linkage looks across the whole genome of related siblings and identify for any variants (National Institutes of Health 2011).  

These approaches help in the identification of three major genes: FOXP1, FOXP2 and CNTNAP2 (Newbury & Monaco 2010). These consider fundamentals genes and plays direct reaction on speech and language impairments. Each one encode for specific protein and any mutation play major role in speech and language deficits (Newbury & Monaco 2010).

Though these approaches seem effective, they have limitations also. The methods were limited on related families by blood and on small cohort of individuals (Newbury & Monaco 2010). They also do not reveal the genes that cause the impairments instead they look for similar genetics variants and most frequent ones (Newbury & Monaco 2010).   

However, recent advance in genetics technology provide best alternative methods for GWL/A studies. The tool of DNA sequence helped scientists today to sequence entire genome of any individual which can cover large sample sizes (Newbury & Monaco 2010). This also helped them to look for genetics variants across different families.   

For more in depth information visit:

Ehab Melibary 

Cited from:
Newbury, DF & Monaco, AP 2010, ‘Genetic Advances in the Study of Speech and Language Disorders’,
Neuron, vol. 68, no.2, pp. 309-320

National Institutes of Health 2011, Genome-Wide Association Studies, viewed 16 September 2011, <>.

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