Quick questions on Future directions of genetic research: germline editing, gene drives and synthetic biology: HSC Biology Module 6

Technically possible since 2014 (CRISPR in mouse embryos) and demonstrated in humans by He Jiankui in 2018, who edited the CCR5 gene in twin embryos in an attempt to confer HIV resistance. He was prosecuted in China and the scientific community condemned the experiment as premature and unethical.

Prevention of severe inherited disease in families where preimplantation diagnosis cannot help (both parents homozygous for a recessive condition).

Banned or strictly limited in almost every jurisdiction; a global moratorium has been proposed by leading scientists.

Irreversibility, cross-border spread, ecosystem consequences, governance gap.

A "search and replace" CRISPR system that can write small new sequences into a chosen location without a double-strand break. Lower off-target rate than original CRISPR-Cas9. Approaching clinical trials for sickle cell and other monogenic diseases.

Converts one base directly to another (e.g. C to T) without cutting both strands. Verve Therapeutics has run trials for inherited hypercholesterolaemia.

Identify two key differences between somatic gene therapy and germline gene editing. [2 marks]

A gene drive is designed to spread an infertility allele through the cane toad population. If 1 percent of toads in northern Queensland are initially modified and the drive ensures 95 percent of their offspring inherit the allele, predict the proportion of toads carrying the allele after 5 generations, assuming no selection cost. [3 marks]

Evaluate the ethical and societal implications of human germline editing. (a) Describe the He Jiankui CCR5 case of 2018. (b) Identify two ethical concerns.