Karyomegalic interstitial nephritis: A case series and review of the literature on genetic insights and clinical challenges

Karyomegalic interstitial nephritis (KIN) is a rare hereditary form of chronic interstitial nephritis that was first described over 50 years ago. It is characterized by karyomegalic tubular epithelial cells and progressive chronic kidney disease, often leading to end-stage renal disease by the fifth decade of life. Recent studies have identified FAN1 mutations as a key genetic contributor, with additional associations to environmental factors and toxic exposures, such as ochratoxin A, alkylating agents, and heavy metals, which may act as potential triggers of the disease. We present a detailed analysis of KIN cases, highlighting genetic diversity, clinical manifestations, and management challenges, complemented by a comprehensive review of the literature.