The patient was one year old and had a fever when one month old. Diagnosed as pneumonia in the local hospital, the baby improved after 8 days of treatment. The baby liked drinking water after birth. At the age of 3 months, low fever often occurred after getting up in the morning. After the baby drank a lot of water, the heat retreated. Since the onset of the disease, the baby suffered low spirit, irritability, deficiency of spleen and stomach and slow weight growth. At present, the baby was in the pediatric intensive care unit and the hospital had issued a critical illness notice.

The family was advised to adopt WES to figure out the genetic cause of the disease and the results showed that the child carried the AQP2 gene p.M1I and p.G165D variants. The associated disease of this gene in the OMIM database is nephrogenic diabetes insipidus, the main clinical manifestations of which are short stature, vomiting, constipation, poor feeding, irritability, polyuria, seizures, and dehydration. Patients with recurrent attacks may suffer from mental retardation, irritability and fever. Sanger validation indicated the two variants were inherited from parents with normal phenotype. According to the classification criteria and guidelines of ACMG genetic variation, the above two were rated as suspected pathogenicity variation. According to the genetic model, the above two variants can explain the phenotype of the baby. By identifying the cause of disease through gene detection, accurate methods can be taken to avoid dehydration and adverse effects on intellectual development.