The idea of creating a new human variant suitable for medical research through genetic engineering currently faces huge challenges in many aspects, including ethical, technical and legal aspects. 1. **Limitations of science and technology**: Although gene editing technologies, such as CRISPR-Cas9, have made significant progress, our understanding of the human genome is still limited. Genes interact in a complex way, and changes in a single gene may lead to unexpected consequences. 2. **Ethical issues**: Creating new "human variants" involves profound ethical issues, including respect for human dignity and potential social inequality. Medical research usually follows strict ethical principles involving the protection of experimental subjects, and the creation of new variants may trigger widespread controversy in terms of human rights and ethics. 3. **Legal framework**: Many countries and regions have strict laws and regulations on the use of gene editing technology, especially in research involving human embryos and germ cells. In addition, international consensus and legal framework on human gene editing have not yet been fully established. 4. **Social impact**: The creation of new variants may have a profound impact on society, including on human identity, mental health and social structure. Although genetic engineering can be used to change the genes of cells or animals in the laboratory, the progress of direct application to human research will be limited until ethics and technology are more mature. Future research needs to find a balance between technology, safety, ethics and social impact to ensure that the direction of scientific development is beneficial to human society.