Speech Sound Disorders Paper

Introduction

The study of the etiology of speech sound disorders (SSD) involves research into their relationship with genetic factors. The complexity of genetics leads researchers to take different approaches when pursuing investigations. Many studies analyze the association of speech and genetics by comparing and contrasting the speech traits of family members. Within this perspective, much research has been done on identical and fraternal twins. This method provides a qualitative understanding of the heritability of speech disorders. Studies also employ a more biological approach. Researchers within this domain study DNA samples to identify specific genes, their location, sequences, and mutations to distinguish the effects that genetic

Kovas et al. (2005) compared the correlations between identical twins, who have identical DNA and fraternal twins who have DNA that is only half as identical. Kovas et al. (2005) examined 787 four and a half year old twins to examine the degree to which genetic and environmental factors impact speech and language. The twins’ phonology and other areas of language were tested over three years. Correlations for the dizygotic (DZ), fraternal tiwns, and monozygotic (MZ), identical twins, were constructed by the differences between the assigned values of the environmental factors and heritability. The results indicated that identical twins performed more similarly than fraternal twins on tests of phonology and other areas of language. The results also revealed that heritability was more influential than environmental factors on phonological and language skills (Kovas et al, 2005). This study helps to establish the importance of genetic inheritance on an individual’s phonological ability. Results also indicate that as an individual ages, genetic influences become more impactful and the influences of a shared environment become less apparent (Kovas et al, 2005). This trend highlights the long-term significance of genetic influence on phonology as the impact grows throughout

The researchers examined the complexity of genetic influence on speech sound disorders. The twins had unintelligible speech and abnormalities of the face, ears, lips, teeth, and chest. Several of their relatives also had speech and language related disorders. The twins had a sister with reading difficulties, a cousin, aunt, and grandmother with dyslexia, an aunt born without maxillary incisors, and a cousin with cleft lip and dyslexia. A genetic assessment identified the cause of their CAS as a genetic mutation based on a small deletion. The mutation was inherited from their mother who had never experienced any difficulty with speech or language. The researchers postulated that although they shared some of the genetic basis of CAS, the disorder did not surface in the mother because the disorder may be more likely caused by a series of deficits in more than one genetic area or a culmination of disruptions in the DNA, rather than by a single mutation (McNeill, Gillon, &Dodd, 2009). The results emphasize the complexity of how an inherited trait collects within families and the intricacies of the genetic