Maturity-onset diabetes of the young (MODY) is characterized by the onset of hyperglycemia at an early age. It is inherited in an autosomal-dominant pattern with pathogenic variants in at least 14 genes, accounting for less than 5% of the diabetes cases. Among those, ABCC8-MODY12 is a very rare form, and diabetic kidney disease in such patients has not been reported so far (Lin et al., 2020; Timmers et al., 2021).

In 2012, a Syrian male teen aged 15 years fled his home country because of war. Upon entering Turkey, he then reached Bulgaria. During the height of the Syrian migrant crisis in Europe, he arrived in Austria in 2015. The non-obese teen with a low average height of 155.5 cm was diagnosed with type 1 diabetes in the first 10 years of his life. His family history disclosed several relatives with a diagnosis of diabetes not characteristic of type 1 or 2, many of them living in Syria (the pedigree of this family is shown in Figure 1A). In Austria, the teen was reported with recurrent uncontrolled hyperglycemia and microvascular complications, including retinopathy, neuropathy, and osteomyelitis due to diabetic foot ulcers, which resulted in frequent hospital admissions. In 2021, the then 24-year-old Syrian migrant was conclusively diagnosed with ABCC8-MODY12, and a course of sulfonylurea was administered instead of insulin. It is worth noting that insulin therapy was eventually re-introduced. Next-generation sequencing and analysis of a MODY panel revealed a likely pathogenic missense variant in exon 10 of ABCC8 (c.1616A>G; p. Tyr539Cys; heterozygous; ClinVar ID 35606) and ruled out relevant variants in other genes (AKT2, APPL1, BLK, CEL, CELP, EIF2AK3, FOXP3, GATA6, GCK, GCKR, GLIS3, GLUD1, HADH, HNF1A, HFN1B, HNF4A, HYMAI, INS, INSR, KCNJ11, KLF11, NEUROD1, PAX4, PDX1, PLAGL1, PTF1A, SLC16A1, SLCA2, WFS1, and ZFP57). Serum C-peptide and proinsulin were in the reference range, suggesting that endogenous insulin production was present and autoantibodies to glutamic acid decarboxylase (GAD), insulin (IAA), and protein tyrosine phosphatase (IA–2A) were undetectable. Furthermore, no diabetic ketoacidosis was reported.

Kidney function in this patient was not impaired upon arrival in Austria (CKD G1A3) but gradually declined thereafter. In parallel, worsening of albuminuria and proteinuria was recorded with albumin-to-creatinine and protein-to-creatinine ratios of up to 16.9 g/g and 22.1 g/g, respectively. In 2022, at the age of 25 years, a kidney biopsy showed severe nodular glomerulosclerosis (the kidney biopsy is shown in Figure 1B). In the present case, severe proteinuria did not respond to conventional medical therapy, and he commenced hemodialysis a few weeks after his kidney biopsy. Persistent severe nephrotic syndrome after initiation of renal replacement therapy necessitated medical nephrectomy with a high dose of angiotensin receptor blocker and non-steroidal anti-inflammatory drug therapy, which was, however, not successful. After the addition of gliquidone to insulin therapy, glucose levels were fairly well controlled, with an HbA1c of 55 mmol/mol. Notably, glycemic control was not achieved with insulin therapy alone and markedly improved after definitive genetic diagnosis and the addition of a sulfonylurea (Figure 1C ).

Pathogenic or likely pathogenic variants in ABCC8 are present in about 15% of individuals with neonatal diabetes and in some 2% of patients with MODY-monogenic diabetes (De Franco et al., 2015; Gaál et al., 2021; Rafique et al., 2021). With regard to diabetic kidney disease, microalbuminuria was indeed observed in some patients with ABCC8-MODY12. However, diabetic end-stage kidney disease in patients with ABCC8-MODY12 has not been reported until now. Thus, our case highlights 1) the potential risk for early-onset and severe diabetic kidney disease in patients with ABCC8-MODY12 and 2) the importance of timely molecular genetic diagnosis in unusual cases of diabetes (young age, positive family history of diabetes, and detectable endogenous insulin production with negative diabetes-associated antibodies) to allow for proper treatment, including SGLT2i medication, and prevention of late sequelae of diabetes (Ovsyannikova et al., 2016).

The patient provided written informed consent for the publication of this case report.