Genetic disorders as models of mathematics learning disability: Fragile X and turner syndromes

Neurodevelopmental disorders and mathematics learning disability: Poor math achievement is well documented in both children and adults with fragile X or Turner syndrome (Bennetto et al., 2001; Brainard et al., 1991; Grigsby et al., 1990; Mazzocco, 1998, 2001; Rovet, 1993; Rovet et al., 1994; Temple & Marriott, 1998). However, there is limited understanding of the cognitive mechanisms that contribute to these poor math outcomes. Specification of these underlying causes is the necessary next step in research on the cognitive phenotypes for these disorders (Mazzocco & McCloskey, 2005). Our efforts to understand the origins of mathematical cognition in fragile X and Turner syndromes are guided by existing knowledge in the field of mathematics learning disability (MLD). This body of research provides a conceptual framework for the contribution of different cognitive systems, such as executive function, visual–spatial, and language skills, to overall competence in mathematics (see Geary, 1993, 1994) as elaborated later in this chapter. Accordingly, the assessment of math ability in persons with fragile X or Turner syndrome is most informative when examined in the context of the overall cognitive phenotype, or the set of cognitive characteristics, associated with each disorder. Although models of MLD are informative for understanding mathematical functioning in genetic conditions such as fragile X or Turner syndrome, the study of these syndromes may also inform the broader field of MLD research.