Abstract
RATIONALE: Maturity-onset diabetes of the young (MODY) is a group of autosomal dominant monogenic diabetes mellitus with a wide range of clinical manifestations that require distinct treatment strategies. MODY9 (OMIM # 612225) is a rare type of MODY, caused by a mutation in the Paired box gene 4 (PAX4). PATIENT CONCERN: A 19-months boy was admitted to the department of endocrinology at Beijing Children's Hospital due to excessive water drinking, polyuria for over half a month, and wheezing for 3 days. DIAGNOSE: The whole-exon sequencing analysis demonstrated that the child carried the heterozygous missense mutation of c.487>T in the 7th exon region of PAX4 gene and diagnosed MODY9. INTERVENTION: The patient was treated with fluid therapy, ketosis correction, insulin, and anti-infection treatment. OUTCOMES: After 17 days in the hospital, the blood glucose levels remained stable and the patient was discharged. LESSONS: In Chinese children, the heterozygous mutation of c.487C>T in the PAX4 gene can lead to the occurrence of MODY9.Gene sequencing analysis is of great significance in the diagnosis and classification of MODY.