Children experiencing difficulties in reading and math represents an important public health issue, as struggles with reading and math are associated with consequences regarding academic and life success, including but not limited to academic failure and lower socioeconomic status as an adult (Geary, Hoard, Nugent, & Bailey, 2012; Ritchie & Bates, 2013). Highlighting the scope of this problem, a large proportion of U.S. students struggle in reading and math. Startling enough, 20%-25% of fourth-graders fail to reach even partial mastery of grade-level knowledge in reading and math (National Assessment of Educational Progress, 2019). Given the reciprocal influences between reading and math (e.g., Cameron, Kim, Duncan, Becker, & McClelland, 2019) alongside the shared co-occurrence of reading and math difficulties (Landerl & Moll, 2010), it is noteworthy that their development has been mostly studied in isolation of each other (Vanbinst, van Bergen, Ghesquière, & De Smedt, 2020). This is surprising as knowledge on their potential mutual unfolding over time may help inform instruction and types of interventions in both academic outcomes. The aforementioned observation set the foundation for the present study to address the nature of the developmental dynamics between reading and math. The goal of the study was to examine the extent to which reading and math co-develop across elementary grades in academically at-risk children, precisely the key time period for the most rapid reading and math development. We utilized a state-of-the-art approach called latent change

According to the Multiple Deficit Model, comorbidity results when the genetic and environmental risk factors that increase the liability for a disorder are domain-general. In order to explore the role of domain-general etiological risk factors in the co-occurrence of learning-related difficulties, the current meta-analysis compiled 38 studies of third through ninth-grade children to estimate the average genetic, shared environmental, and nonshared environmental correlations between reading and attention-deficit/hyperactivity disorder (ADHD) symptoms, and reading and math, as well as their potential moderators. Results revealed average genetic, shared and nonshared environmental correlations between reading and ADHD symptoms of .42, .64, and .20, and reading and math of .71, .90, and .56, suggesting that reading and math may have more domain-general risk factors than reading and ADHD symptoms. A number of significant sources of heterogeneity were also found and discussed. These results have important implications for both intervention and classification of learning disabilities.

Dyslexia, a specific reading disability, is a common (up to 10% of children) and highly heritable (~70%) neurodevelopmental disorder. Behavioral and molecular genetic approaches are aimed towards dissecting its significant genetic component. In the proposed review, we will summarize advances in twin and molecular genetic research from the past 20 years. First, we will briefly outline the clinical and educational presentation and epidemiology of dyslexia. Next, we will summarize results from twin studies, followed by molecular genetic research (e.g., genome-wide association studies (GWASs)). In particular, we will highlight converging key insights from genetic research. (1) Dyslexia is a highly polygenic neurodevelopmental disorder with a complex genetic architecture. (2) Dyslexia categories share a large proportion of genetics with continuously distributed measures of reading skills, with shared genetic risks also seen across development. (3) Dyslexia genetic risks are shared with those implicated in many other neurodevelopmental disorders (e.g., developmental language disorder and dyscalculia). Finally, we will discuss the implications and future directions. As the diversity of genetic studies continues to increase through international collaborate efforts, we will highlight the challenges in advances of genetics discoveries in this field.

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A risk to develop a learning disability has been shown to run in families. Having a positive family history of learning disability seems to account for mean differences in achievement outcomes (reading, math) in that children with a positive family history score significantly lower compared to their peers with no such family history. However, the role of family history status in explaining etiological (genetic and environmental) differences among these subgroups of children has yet to be established. The present study of 872 twins ( M = 13.30, SD = 1.40) from the Florida Twin Project on Reading, Behavior, and Environment utilized a multigroup approach to examine etiological differences on reading, spelling, and math among two subgroups defined by family history status. Results showed significant mean differences on all achievement outcomes, aside from math; however, no significant etiological differences on any achievement outcome were found among the two subgroups. Results support previous literature that the risk for developing a learning disability is transmitted through a family, but this is seemingly not manifested by differential etiology.