Abstract:

Objective To describe the diagnosis, treatment, and follow-up of a child with isolated proteinuria attributable to CUBN mutations, and to contextualize the case with a literature review. Methods We retrospectively reviewed one pediatric case of isolated proteinuria and surveyed relevant published reports. Results A 3-year-old boy with normal growth and development and no family history of kidney disease presented with subnephrotic, albumin-predominant proteinuria in the absence of edema or oliguria. Renal function was preserved, and megaloblastic anemia was not present. Genetic testing identified two heterozygous CUBN variants: A nonsense variant in exon 42, c.6360G>A (p.Trp2120*), and a frame shift variant in exon 47, c.7341delC (p.Ser2448Valfs*45). These findings are consistent with autosomal recessive chronic benign proteinuria. The patient received an angiotensin-converting enzyme inhibitor plus Bailing capsules. During 2.5 years of follow-up, proteinuria remained stable without clear remission or progression. Conclusion CUBN mutation-associated isolated proteinuria in children appears clinically benign but warrants proactive longitudinal monitoring.

Key words: proteinuria, CUBN gene mutations, pediatrics