A familial study of severe phonological disorders

The present study examined the familial basis for severe phonological disorders. Twenty children with severe phonological disorders and their siblings were compared to 20 normally developing children and their siblings on measures of phonology, language, reading, and motor ability. Results revealed that the siblings of the disordered children performed more poorly than control siblings on phonology and reading measures. Disordered subjects' phonological skills correlated significantly and positively with their siblings', whereas controls' scores did not. Families of disordered children reported significantly more members with speech and language disorders and dyslexia than did families of controls. Sex differences were reflected in the incidence but not the severity or type of disorder present. These findings suggest a familial basis for at least some forms of severe phonological disorders.