Purpose: This study describes risk factors associated with language impairment in children with classic galactosaemia.
Method: Thirty-three 4-16-year-old participants with classic galactosaemia and a history of speech sound disorders completed a battery of cognitive and language measures and their parents completed a family history questionnaire.
Results: Nine of the sixteen (56%) participants with typical cognitive development and 15 of the 17 (88%) with borderline-low cognitive development had language impairments. Participants with typical cognitive development more often had an expressive language disorder, whereas those with borderline-low cognitive development more often had a mixed receptive-expressive language disorder. Participants with Q188R/Q188R genotypes had increased risk for both cognitive and language impairments. The IQs of younger siblings who did not consume milk postnatally were 10-56 points higher than the IQs of their older siblings with galactosaemia who had consumed milk postnatally. However, 4 of 5 younger siblings who were lactose-restricted from birth had language impairments. Typically-reported risk factors for language disorder, including parental history of speech/learning problems and low parental education level, were not significantly associated with cognitive or language impairments in the present sample of children with galactosaemia.
Conclusions: Children with galactosaemia and speech disorders have a 4-6 times greater risk for language impairment than children with early speech disorders of unknown origin. Early dietary lactose may increase the risk for cognitive and language impairments; however, the lack of significant associations of language impairment with days of milk consumption, and other familial and educational risk factors, is consistent with prenatal causation.