In May 2025, doctors in Philadelphia treated a baby with a custom-made gene-editing medicine. The baby had a rare genetic condition that caused dangerous ammonia buildup. Scientists used CRISPR to fix a tiny DNA error. The treatment greatly improved his health.

    BulletsIn

•  Baby born with rare, life-threatening genetic disorder
•  Condition caused ammonia buildup damaging brain and organs
•  About half of affected babies die in infancy
•  Liver unable to remove ammonia due to DNA error
•  Baby too small for liver transplant
•  Doctors propose custom gene-editing medicine
•  Scientists design CRISPR tool for one patient
•  DNA fix like correcting one letter in billions
•  Medicine tested on animals, shown safe
•  FDA approves treatment in just six months
• Baby receives three doses at six months old
• Ammonia levels drop, health improves
•  Baby gains weight, prepares to go home
•  Breakthrough offers hope for rare disease patients