Huntington's disease is caused by a dominant mutation in the first exon of the Huntingtin (HTT) gene on chromosome 4. Specifically, it involves the expansion of the CAG trinucleotide repeat sequence beyond 35 repetitions. This leads to an abnormal elongation of the encoded polyglutamine (polyQ) chain, forming a mutant Huntingtin protein (mHTT). mHTT accumulates abnormally within neurons, forming inclusions that disrupt cellular functions and ultimately lead to neuronal death. Research has shown that a higher number of CAG repeats is associated with an earlier age of onset and more severe disease progression.

Allergic rhinitis (AR), also known as hay fever, is a common chronic inflammatory disease of the upper respiratory tract. Its typical symptoms include rhinorrhea (runny nose), nasal congestion, nasal itching, and repeated sneezing. It is estimated that over 500 million people worldwide are affected by allergic rhinitis. In China, the prevalence of allergic rhinitis among adults is as high as 17.6%, and this number has increased significantly over the past six years.

On May 15, 2025, a research team from the Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania published a landmark study in the New England Journal of Medicine(NEJM): the first successful application of a bespoke gene-editing therapy, developed for a single patient, to treat an infant with a rare and fatal genetic disorder—carbamoyl phosphate synthetase 1 (CPS1) deficiency.