ROLE OF GENETIC FACTORS IN SPEECH AND LANGUAGE DISORDERS:EVIDENCE FROM PEDIGREE ANALYSIS

Abstract

This study included 50 patients, 25 patients with specific language impairment, their age ranged from 3-6 years and another 25 patients with stuttering, their age ranged from 10-30 years. Pedigree analysis was performed for 25 patients from those investigated for SLI. Family history questionnaire was done for 25 patients from those investigated for I stuttering, in comparison to 25 subjects normal control group. It was found from pedigree analysis that r5 probands of the SLI I group showed that the probability of SLI in the offspring of affected I individuals is approximately 0.5, exactly as would be predicted if a single

dominant gene was implicated in the etiology. Moreover, the number of affected probands: non-affected equaled 23:25 i.e. I:I which is consistent I with autosomal dominant mode of inheritance. However, in the other 10 I constructed pedigrees the pattern of inheritance was not compatible with that line of reasoning since affected children were found among the I offspring of unaffected parents. I We concluded that SLI is transmitted via autosomal dominant mode of inheritance .The departure from this classical dominant mode of I inheritance could reflect misclassification of family members, etiological I heterogeneity (with some cases due to polygenic or non-dominant inheritance). I

It was found from the family history questionnaire that was done for the I stuttering group that about 96% of subjects had family history of stuttering, in comparison to 4% in the control group and about 28% of I subjects had one or more affected siblings. I