Evolution of ASPM coding variation in apes and associations with brain structure in chimpanzees

Area of Science:

• Evolutionary biology
• Neuroscience
• Genetics

Background:

• The ASPM gene is crucial for human brain development, with mutations linked to microcephaly.
• Understanding ASPM's role in non-human primates can illuminate human brain evolution.
• Limited research exists on the impact of common ASPM variations in primates.

Purpose of the Study:

• To investigate coding variation in the chimpanzee ASPM gene.
• To examine associations between ASPM genotypes and brain morphology in chimpanzees.
• To explore evolutionary patterns of the ASPM gene across primate lineages.

Main Methods:

• Genotyping of five non-synonymous ASPM polymorphisms in 241 chimpanzees.
• Magnetic resonance imaging (MRI) to measure brain structures (total volume, gray/white matter, ventricles, cortical surface area).
• Comparative analysis of ASPM protein evolution across chimpanzee, bonobo, and human lineages.

Main Results:

• A potential association was found between the ASPM V588G genotype and chimpanzee cerebral ventricular volume.
• No significant associations were observed between other ASPM genotypes and the measured brain morphology traits.
• Accelerated ASPM protein evolution signatures were identified independently in chimpanzee, bonobo, and human lineages.

Conclusions:

• ASPM gene variation may influence natural variation in cerebral cortical development in non-human primates.
• The findings suggest a potential role for ASPM in shaping brain structure diversity.
• Further functional studies are needed to elucidate the precise mechanisms of ASPM's influence on brain morphology.