From CNTNAP2 to Early Expressive Language in Infancy: The Mediation Role of Rapid Auditory Processing

<span class="paragraphSection"><div class="boxTitle">Abstract</div>Although it is clear that early language acquisition can be a target of <span style="font-style:italic;">CNTNAP2</span>, the pathway between gene and language is still largely unknown. This research focused on the mediation role of rapid auditory processing (RAP). We tested RAP at 6 months of age by the use of event-related potentials, as a mediator between common variants of the <span style="font-style:italic;">CNTNAP2</span> gene (rs7794745 and rs2710102) and 20-month-old language outcome in a prospective longitudinal study of 96 Italian infants. The mediation model examines the hypothesis that language outcome is explained by a sequence of effects involving RAP and <span style="font-style:italic;">CNTNAP2</span>. The ability to discriminate spectrotemporally complex auditory frequency changes at 6 months of age mediates the contribution of rs2710102 to expressive vocabulary at 20 months. The indirect effect revealed that rs2710102 C/C was associated with lower P3 amplitude in the right hemisphere, which, in turn, predicted poorer expressive vocabulary at 20 months of age. These findings add to a growing body of literature implicating RAP as a viable marker in genetic studies of language development. The results demonstrate a potential developmental cascade of effects, whereby <span style="font-style:italic;">CNTNAP2</span> drives RAP functioning that, in turn, contributes to early expressive outcome.</span>

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