Senior-Løken Syndrome with “Salt and Pepper” Nephromegaly: Expanding the Radiological and Genetic Spectrum of SCLT1 – A Case Report

Senior-Løken syndrome (SLS) is a rare renal-retinal ciliopathy usually associated with small nephronophthisis kidneys, whereas the “salt and pepper” microcystic pattern is classically attributed to autosomal recessive polycystic kidney disease (ARPKD). We report a 17-year-old girl with retinitis pigmentosa, early onset polyuria-polydipsia, and advanced kidney failure whose ultrasound and MRI showed bilateral nephromegaly with a diffuse “salt and pepper” echotexture, suggestive of ARPKD. Whole exome sequencing, however, identified a novel homozygous 4 bp deletion at the invariant 5′ donor splice site of intron 6 in SCLT1 (c.425_426+2del), predicted to abolish normal splicing and classified as likely pathogenic by ACMG criteria. This case uniquely links SCLT1-related-SLS to a proliferative, microcystic nephromegalic phenotype, expanding both the radiological and mutational spectrum of the syndrome and underscoring the decisive role of genomic testing in resolving discordant clinical and imaging features in adolescent ciliopathy-associated cystic kidney disease.