ObjectiveTo explore the efficacy of ketogenic diet on developmental and epileptic encephalopathy caused by PIGA gene mutation. Method A retrospective analysis was conducted on patients with developmental and epileptic encephalopathy admitted to Guangdong Sanjiu Brain Hospital from March 2016 to June 2020. Patients with positive PIGA gene mutations were selected, and their clinical characteristics and treatment effects were analyzed. ResultA total of 6 epilepsy patients with positive PIGA gene mutations were collected, all of whom were male. 5 cases were heterozygous mutations originating from the mother, and 1 case was a new mutation. All 6 patients were accompanied by varying degrees of psychomotor developmental delay, various types of epileptic seizures, multifocal discharge on EEG, and varying degrees of brain hypoplasia indicated by cranial MRI. All 6 patients met the criteria for drug-resistant epilepsy and were recommended to undergo ketogenic diet treatment, but three patients were discontinued in the early stages. Among them, Case 3 experienced hyperlipidemia on the fifth day of ketogenic diet and was discontinued, while Case 5 experienced transient hypoglycemia on the second day and the family refused to use it. Case 6: After one week of ketogenic diet, the family members voluntarily stopped using it. Only three patients adhered to a long-term ketogenic diet for more than 2 years. The efficacy of ketogenic diet treatment in cases 1 and 4 was very significant, reaching a seizure free state. Case 2 showed a 50% reduction in seizure frequency after ketogenic diet treatment. Case 4 developed hyperlipidemia after two years of ketogenic diet, and after discontinuing the ketogenic diet for about two months, the blood lipids returned to normal. Comparing patients in the ketogenic group with those in the non ketogenic group, it was found that the ketogenic group had a clear therapeutic effect after treatment. Among them, two patients had no seizures for more than a year and showed significant progress in development compared to before. Two years after ketogenic diet treatment, the EEG showed a significant decrease or disappearance of epileptic discharge compared to before. ConclusionPatients with developmental latency caused by PIGA gene mutations have an early only age, diverse types of sizes, varying degrees of psychomotor developmental delay, and some are compatible by von as possible.