# Systemic and Ocular Manifestations of a Ciliopathy: A Case Report of Renal–Retinal Involvement in Senior–Loken Syndrome

## TL;DR

A rare genetic disorder called Senior–Loken syndrome is diagnosed in a young woman with kidney disease and retinal dystrophy, highlighting the importance of genetic testing and multidisciplinary care.

## Contribution

This case report provides a clinical and genetic confirmation of Senior–Loken syndrome in a patient with renal–retinal involvement, emphasizing the diagnostic value of genetic testing.

## Key findings

- The patient exhibited retinal dystrophy and end-stage renal disease, consistent with Senior–Loken syndrome.
- A pathogenic variant in the NPHP1 gene was identified, confirming autosomal recessive inheritance.
- Multidisciplinary evaluation, including ophthalmology and genetics, was critical for diagnosis.

## Abstract

Background: Senior–Loken syndrome (SLS) is a rare autosomal recessive ciliopathy classically defined by the concurrence of nephronophthisis, frequently progressing to end-stage renal disease (ESRD), and retinal dystrophy, most commonly presenting as retinitis pigmentosa (RP). Given its phenotypic overlap with other renal–retinal syndromes, establishing a definitive diagnosis necessitates integrated clinical evaluation and molecular confirmation. Case Presentation: A 28-year-old Chinese female presented with a two-month history of binocular floaters. Her medical history was significant for ESRD of five years’ duration, managed with maintenance hemodialysis. Ophthalmic assessment revealed retinal pigment mottling along the inferior temporal arcades and generalized arterial attenuation. Spectral-domain optical coherence tomography demonstrated outer retinal thinning with loss of the ellipsoid zone at corresponding locations. Perimetry confirmed visual field constriction, and full-field electroretinography showed severely reduced rod- and cone-mediated responses. Genetic testing was performed and a pathogenic variant in the NPHP1 gene was identified. Segregation studies confirmed both parents as heterozygous carriers, consistent with autosomal recessive inheritance. Collectively, these findings established a diagnosis of SLS. Conclusions: This case reinforces that SLS should be considered in the differential diagnosis of any young patient exhibiting RP alongside chronic kidney disease, particularly in the setting of early-onset ESRD. It also illustrates the essential role of a coordinated, multidisciplinary approach—encompassing nephrology, ophthalmology, and genetics—in diagnosing complex ciliopathies. Genetic confirmation not only validates the clinical diagnosis but also provides a foundation for family counseling, prognostic stratification, and future eligibility for gene-specific therapeutic trials.