CRISPR-CAS9, a genome-editing technology, permits cheap and exact modification of human DNA in relation to biomedical study. But, an expert has claimed that the technique couldn’t function in the case of altering complex human traits like intelligence.

Professor of the Rollins School of Public Health (RSPH) at Emory University, Cecile Janssens explained that scientists are required to notice what can and can’t be genetically edited in human DNA. She said that there are two requirements that have to be met for a genetic trait to be modified.

Janssens said that firstly the traits are required to be mainly determined by DNA. The trait’s heritability must be near to 100%.

When heritability is low, non-genetic factors like stress, education and lifestyle can notably affect the trait. She added that with it the trait will less likely be genetically modifiable.

She described an earlier meta-analysis of study on heritability featured in Nature Genetics, saying that just a few traits had an estimated heritability above 90%.The research discovered that the heritability of intelligence and higher-level cognition functions was just around 50%, muscle power’s heritability was at 70%, and the heritability of personality and temperament was at 45% only.

Secondly she mentioned that the genetic architecture should be clear-cut. Janssens mentioned that the traits have to be the result of a single mutation or by an interaction between a restricted numbers of mutations for being genetically modifiable.

Diseases like Duchenne muscular dystrophy and sickle cell disease, which is a severe blood disorder that happens due to a single-gene mutation of beta-thalassemia, are the next targets for gene editing. Furthermore, Janssens added that research using CRISPR could result into discoveries for therapies and possible prevention of the above mentioned diseases.