Gene discovery offers new hope for patients with neurodevelopmental disorders

Researchers from the GREGoR Research Center at Baylor College of Medicine, the Chinese University of Hong Kong, the German Mouse Clinic, and other institutions have successfully diagnosed 20 patients with previously undiagnosed neurodevelopmental disorders. The breakthrough was achieved through an international effort that involved analyzing the patients’ genes and conducting family studies to identify genetic mutations responsible for their conditions.

The study revealed that all 20 patients had mutations in the DHX9 gene, leading to disruptions in its normal function. Surprisingly, this was the first time that the DHX9 gene has been linked to a human disease. Animal models further confirmed the connection between defective variations of the gene and neurodevelopmental issues.

Dr. Daniel Calame, the first author of the study, highlighted that the patients’ conditions varied significantly, ranging from severe developmental disorders with intellectual disabilities, seizures, and movement problems, to milder conditions like autism or nerve degeneration causing neuropathy. To investigate these diverse effects, the researchers conducted laboratory experiments, introducing different DHX9 variants from the patients into cells and comparing their functions with the normal DHX9 variant.

The results showed that some severe cases of neurodevelopmental disorders were associated with DHX9 variants located outside the cell nucleus, while another variant increased double-stranded DNA breaks, leading to disruption of normal cellular functions. Additionally, animal models with the Dhx9 gene eliminated displayed reduced activity in new environments and impaired hearing, highlighting the gene’s role in regulating neurodevelopment and neuronal well-being.

Overall, this study showcases the power of international collaboration in genetic research and provides valuable insights into neurological diseases from a gene and genomic variation perspective. The research brings together scientists from different parts of the world, including Hong Kong and Houston, in a remarkable story of scientific achievement. The findings are published in The American Journal of Human Genetics.

Source: Baylor College of Medicine

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