The child, Anan, was 1 year old. She had fever when she was born in January, and the local hospital was diagnosed with "pneumonia", which improved after 8 days of treatment. Anan like drinking water after birth, from 3 months of age there is a low fever occurred in the morning, after drinking more water, heat can be retired. Before 2 months, the patient had a high fever, and the fever peaked 1-2 times a day. Drinking more and urinating aggravated the patient's thirst. After drinking a lot of water, the symptoms were relieved slightly. Since the onset of the disease, the spirit is general, if the water is forbidden, then easy to anger, irritable, stomach tolerance, stool dry knot, weight growth is slow, nearly 3 months to weight did not increase. At present has been admitted to the children's intensive care unit, the hospital issued a critical notice.

The doctor suggested that the family should sequence the whole exome of the child to seek the genetic cause of the disease. The results showed that the child carried the AQP2 gene p.M1I and p.G165D mutations. The related disease of this gene in the OMIM database is renal diabetes insipidus, and the main clinical manifestations are: short stature, vomiting, constipation, poor feeding, polydipsia, polyuria, seizures, and repeated dehydration patients may have mental retardation and irritability , Fever, etc. After Sanger verification, the above two mutations were inherited from parents with normal phenotypes. According to the ACMG genetic variation classification criteria and guidelines, the above two variants are rated as suspected pathogenic variants. According to the genetic pattern, the above two variants can explain the phenotype of the child. Through genetic testing to determine the cause of the disease, it is possible to prevent dehydration in an accurate manner and prevent adverse effects on intellectual development.