Specific language impairment (SLI) is a common developmental disorder characterized by difficulty in language acquisition despite otherwise normal development and in the absence of any obvious explanatory factors. This disorder affects 5 to 8% of preschool children and ... Specific language impairment (SLI) is a common developmental disorder characterized by difficulty in language acquisition despite otherwise normal development and in the absence of any obvious explanatory factors. This disorder affects 5 to 8% of preschool children and is highly heritable yet multifactorial (Newbury et al., 2009). - Genetic Heterogeneity of Specific Language Impairment Multiple loci for specific language impairment have been mapped including SLI1 on chromosome 16q; SLI2 (606712) on chromosome 19q; SLI3 (607134) on chromosome 13q21; SLI4 (612514) on chromosome 7q35-36; and SLI5 (615432), caused by mutation in the TM4SF20 gene (615404) on chromosome 2q36.