The child, Anan, was 1 year old.She was diagnosed with "pneumonia" by the local hospital. 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.

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. 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.