Patient gao, 28 years old, mental retardation, hair yellow, skin white, body fluid, urine has pungent smell, naked eye hematuria, wash meat water sample, accompanied by a little foam urine, not accompanied by frequency, urgency, urine pain, urinary line interruption, micturition difficulty. The clinical diagnosis is suspected to be phenylketonuria (PKU).His wife, with a normal phenotype, had been married for two years and was desperate to have a healthy baby.

Since phenylketouria is an autosomal recessive genetic disease, the doctor advised the patient to find the cause by genetic and metabolic disease gene test, the results showed that the patient carried PAH gene p. The disease associated with this gene in OMIM database is phenylketonuria, and its clinical manifestations are microcephaly, mental retardation, obsessive-compulsive disorder, depression, anxiety, hyperphenylalanine, phenylpyruvemia, etc. The above two mutations were proved to be compound heterozygous ones. Since the patient wants to have a healthy baby, it is recommended that his wife also undergo genetic testing to assess the couple's risk of having children with the disease. Results the wife showed no PAH gene mutation. After adequate communication and genetic counseling, the couple decided to conceive naturally and make timely prenatal diagnosis to ensure a healthy baby.