RFX6 heterozygous frame-shift variation causes maturity-onset diabetes mellitus of the young (MODY) with refractory hyperlipidemia: a case report.

Background: Maturity-onset diabetes mellitus of the young (MODY) is a form of autosomal dominant inherited diabetes, featuring diverse clinical characteristics due to distinct pathogenic gene mutation sites. Reports on MODY caused by RFX6 mutations are scarce, and it is prone to being misdiagnosed as type 1 or type 2 diabetes in clinical settings. To date, no cases have been reported regarding patients with RFX6 gene mutations accompanied by refractory hyperlipidemia, and the treatment remains undetermined. We present a rare case of a 13-year-old Chinese girl who was admitted to the Third Affiliated Hospital of Soochow University with diabetes combined with refractory hyperlipidemia.

Case description: A 13-year-old adolescent female presented with persistent dry mouth, polydipsia, and polyuria. The physical examination accidentally found high blood glucose. She had refractory hyperlipidemia in the past and was treated with a variety of lipid-lowering programs, but her lipids were still poorly controlled. Due to the patient's early age of onset, the special type of diabetes cannot be excluded, and she is recommended to be further examined in our hospital.

Conclusions: We sequenced the MODY-related genes of the patient and her mother. RFX6 heterozygous frame-shifting variants were found in the proband and her mother (NNM_173560:c.1500delT). The patient was eventually diagnosed with MODY. During the hospitalization, we treated the patient with insulin hypoglycemic treatment, and the patient's blood glucose was stable. Surprisingly, the patient's blood lipid also decreased significantly, and even without using any lipid-lowering drugs, the blood lipid remained at a low level.