Genetic Syndromes as Model Pathways to Mathematical Learning Difficulties: Fragile X, Turner, and 22q Deletion Syndromes

The difficulties that children with mathematics learning disability (MLD) experience are linked to both numerical and nonnumerical skills. At issue is that the combination of difficulties experienced by any one child varies across cases of MLD. An approach to identifying distinct pathways to MLD is to study genetic disorders for which well-described cognitive phenotypes include poor math achievement. Using this approach, we summarize research on three common genetic disorders: fragile X, Turner, and chromosome 22q11.2 deletion syndromes. Evidence from these studies suggests that children with numerical and arithmetic impairments differ in the specificity of their difficulties as well as the relation between their math and executive function skills. In light of these and other differences, the notion that a single cognitive impairment is common to each disorder is not supported. The findings summarized in this chapter add to the growing body of evidence that MLD is heterogeneous, and counters notions that a single core deficit underlies MLD.