Maturity-onset diabetes of the young (MODY) is a rare, autosomal dominant disease characterized by non-ketogenic diabetes mellitus (DM). MODY type 4, caused by PDX1 mutation, is a very rare subtype of MODY, especially in Korea. We report a case of a 10-year-old, nonobese girl with a family history of type 2 DM. After diagnosis, the patient’s serum glucose level was well controlled using metformin monotherapy; however, the glycated hemoglobin level increased to 9.0% approximately 2 years after treatment. No obesity or lifestyle problems were observed, and serum fasting C-peptide level was within the normal range. Furthermore, no islet-related autoantibodies were detected. A genetic screening for MODY using a next-generation sequencing panel was performed, and a likely heterozygous pathogenic PDX1 mutation (p.Gly246ArgfsTer21) was identified. The PDX1 variant was not detected in her mother, implying that the mutation had arisen de novo in the proband. She was prescribed insulin degludec in addition to metformin therapy, which improved her hyperglycemia. This report presents a novel MODY type 4 phenotype and highlights the importance of genetic screening in patients with MODY characteristics.

Purpose: Fish allergy is rare in children, and there have been few studies on childhood fish allergy. This study aims to investigate the clinical characteristics and laboratory findings of white meat fish (WMF) allergy in Korean children. Methods: In this study, we enrolled 150 children with a history of WMF consumption who underwent serum specific immunoglobulin E to cod (cod-sIgE) at Ajou University Hospital from January 2019 to December 2022. The demographic characteristics, clinical symptoms, history of consuming 6 major Korean WMF (cod, cutlass, yellow croaker, brown sole, olive flounder, and anchovy), and cod-sIgE were investigated. Results: Sixty-five subjects (43.3%) had clinical responses to at least 1 of the 6 WMF (WMF-allergic), and 85 subjects had no allergic reaction to all 6 WMF (WMF-tolerant). The median age of first symptom onset in the WMF-allergic group was 15 months. Major causative WMF were yellow croaker (30.6%), cutlass (28.7%), cod (26.1%), brown sole (20.4%), anchovy (14.7%), and olive flounder (6.5%). Twenty-three of 65 WMF-allergic children (35.4%) had anaphylaxis. The median level of cod-sIgE was 4.61 kUA/L (range, 0.04–100.10 kUA/L) in the WMF-allergic group, and this value was significantly higher (P < 0.001) than that of the WMF-tolerant group (0.04 kUA/L; range, 0.04–3.08 kUA/L). The positive rates ( ≥ class 2, 0.7 kUA/L) of cod-sIgE for the 6 individual WMF ranged from 69% to 90%. Conclusion We propose that WMF allergy can develop in young children, with 35.4% experiencing anaphylaxis. Cod-sIgE is considered a useful tool for diagnosing not only cod allergy but also other WMF allergy in children.