Figure 4.

Pleiotropy scenarios for shared versus separate genetic architecture of rhythm and speech/language. The Atypical Rhythm Risk hypothesis predicts that associations between rhythm and speech/language are (a) in part driven by genetic pleiotropy, such that a common set of causal genes affects both phenotypes directly, or (b) mediated genetic pleiotropy, such that genes directly affect rhythm phenotypes, and those phenotypes in turn affect individual differences in acquisition of speech/language during development, or (c) genes directly affect speech/language phenotypes, and those phenotypes affect individual differences in rhythm development. These models should be tested against the null hypothesis of separate genetic architecture. Moreover, a key to understanding the dynamics between genes, brain and behavior will be to test mediating neural endophenotypes linked to (d) shared or (e) separate genetic architecture