Accepted_test

The object of our study is a candidate gene for mental retardation disorders – CNTN6. Most of the associated mutations in this gene are represented by CNVs of large size, but a point mutation was found in only one clinical case. Therefore, we hypothesized the presence of functional regions in the CNTN6 locus, the alteration of which may lead to abnormalities in the early stages of human brain development.

Annotated regulatory elements were not found at this locus, but two regions that evolved rapidly in humans - human accelerated region (HAR) - were identified. These DNA regions may function as enhancers of genes involved in human brain development. Mutations in HAR are also known to alter the expression of candidate genes for various psychiatric disorders. This work aims to study the effect of HAR deletion located in the CNTN6 locus on the early stages of human neurogenesis on the in vitro model systems.

To realize this goal, hiPSC lines with homozygous deletions of HAR were obtained using the CRISPR/Cas9 system. These lines were differentiated into cerebral organoids, for which morphological analysis of the features of the early stages of neurogenesis was performed. Thus, it was found that HAR deletion in the CNTN6 gene leads to decreased organoid size and impaired ventricle-like structure formation, indicating that this region is involved in the regulation of the early stage of human neurogenesis in vitro.