Ketogenic diet (KD) has emerged as a promising dietary intervention in neurological disorders, including epilepsy and ASD.<h4>Objective</h4>This case report investigates the clinical efficacy and potential mechanisms of KD in an ASD patient with a PTEN mutation, providing evidence for genetics-guided precision nutrition therapy.<h4>Methods</h4>We present a 7-year, 1-month-old male with ASD and a pathogenic heterozygous PTEN p. Arg130Gln mutation, who showed suboptimal response to conventional treatments. This evidence concerns the gene PTEN and nervous system disorder.