**1. Introduction**

Learning disabilities are relatively common pediatric conditions, and there is no universal consensus establishing what a learning disability represents [1, 2]. The American Pediatrics Association subcategorizes specific learning disorder as reading, written expression, or

mathematics skills that are substantially lower than expected for the individual's age, measured intelligence, and age-appropriate education level or when achievement falls below a set standard definition [3]. The International Classification of Disease (ICD) identifies learning disability as a condition of arrested or incomplete development in cognitive functioning or in adaptive behavior in the developmental period [4]. It can be evaluated with the general intelligence functioning and supplemented by scales.

Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) is available from 2013. The DSM-V now indicates a unique new category or diagnosis of "specific learning disorder" for issues previously differentiated as: dyslexia, dyscalculia, dysgraphia, and dysorthography. The change was made because there had been no support for a continued distinction among the terms. The single definition joined the "specifiers," and for each of them, the deficit capacities are mentioned with reference to the reading, calculation, and the written language. The DSM-V state classifies the disorder in mild, moderate, and severe. In addition, the risk factors are confirmed as the disturbance of language, familiarity, co-morbidity [5].

During last decades, many studies have been conducted to understand the basis of these neurodevelopmental disorders, leading to the identification of some altered specific neural networks although the mechanisms are not fully understood [6–9].

In this context, the American Association on Intellectual and Developmental Disabilities (AAIDD) identifies prenatal, perinatal, and postnatal causes. Among the prenatal causes, chromosomal disorders, Syndrome disorders (RASopathies), and inborn errors of metabolism can be taken into account; perinatal and postnatal causes often encompass infectious and traumatic etiologies. Several cognitive deficits may be caused by a single-gene mutation and can be classified into discrete clinical conditions with specific diagnoses [10, 11]. Notwithstanding distinct clinical entities could rise from the interaction between genes and environment.

A better understanding of pathophysiological mechanisms that lead to learning disability could provide new insights in knowledge and therapy of intellectual and learning disabilities.
