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.

Sperm flagellum defects are tightly associated with male infertility. Centriolar satellites are small multiprotein complexes that recruit satellite proteins to the centrosome and play an essential role in sperm flagellum biogenesis, but the precise mechanisms underlying this role remain unclear. Serologically defined colon cancer autoantigen protein 8 (SDCCAG8), which encodes a protein containing eight coiled-coil (CC) domains, has been associated with syndromic ciliopathies and male infertility. However, its exact role in male infertility remains undefined. Here, we used an Sdccag8 mutant mouse carrying a CC domains 5-8 truncated mutation (c.1351-1352insG p.E451GfsX467) that models the mutation causing Senior-Løken syndrome (c.1339-1340insG p.E447GfsX463) in humans. The homozygous Sdccag8 mutant mice exhibit male infertility characterized by multiple morphological abnormalities of the flagella (MMAF) and dysmorphic structures in the sperm manchette. A mechanistic study revealed that the SDCCAG8 protein is localized to the manchette and centrosomal region and interacts with PCM1, the scaffold protein of centriolar satellites, through its CC domains 5-7. The absence of the CC domains 5-7 in mutant spermatids destabilizes PCM1, which fails to recruit satellite components such as Bardet-Biedl syndrome 4 (BBS4) and centrosomal protein of 131 kDa (CEP131) to satellites, resulting in defective sperm flagellum biogenesis, as BBS4 and CEP131 are essential to flagellum biogenesis. In conclusion, this study reveals the central role of SDCCAG8 in maintaining centriolar satellite integrity during sperm flagellum biogenesis.

Visual electrophysiology is a valuable tool for evaluating the visual system in various systemic syndromes. This review highlights its clinical application in a selection of syndromes associated with hearing loss, mitochondrial dysfunction, obesity, and other multisystem disorders. Techniques such as full-field electroretinography (ffERG), multifocal electroretinography (mfERG), pattern electroretinography (PERG), visual evoked potentials (VEP), and electrooculography (EOG) offer insights into retinal and optic nerve function, often detecting abnormalities before clinical symptoms manifest. In hearing loss syndromes like Refsum disease, Usher syndrome (USH), and Wolfram syndrome (WS), electrophysiology facilitates the detection of early retinal changes that precede the onset of visual symptoms. For mitochondrial disorders such as maternally-inherited diabetes and deafness (MIDD), Kearns-Sayre syndrome (KSS), and neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome, these tests can be useful in characterizing retinal degeneration and optic neuropathy. In obesity syndromes, including Bardet-Biedl syndrome (BBS), Alström syndrome, and Cohen syndrome, progressive retinal degeneration is a hallmark feature. Electrophysiological techniques aid in pinpointing retinal dysfunction and tracking disease progression. Other syndromes, such as Alagille syndrome (AGS), abetalipoproteinemia (ABL), Cockayne syndrome (CS), Joubert syndrome (JS), mucopolysaccharidosis (MPS), Neuronal ceroid lipofuscinoses (NCLs), and Senior-Løken syndrome (SLS), exhibit significant ocular involvement that can be evaluated using these methods. This review underscores the role of visual electrophysiology in diagnosing and monitoring visual system abnormalities across a range of syndromes, potentially offering valuable insights for early diagnosis, monitoring of progression, and management.

Syndromic genetic disorders affecting vision can also cause hearing loss, and Usher syndrome is by far the most common etiology. However, many other conditions can present dual sensory impairment. Accurate diagnosis is essential for providing patients with genetic counseling, prognostic information, and appropriate resources. This study aimed to describe the genetic profile of combined inherited deaf-blindness in Portugal. This was a cross-sectional study conducted at a tertiary hospital in Portugal. Patients were identified through the national, web-based inherited retinal dystrophies registry (IRD-PT, retina.com.pt). Demographics, clinical, and genetic data were retrieved from individual patient records. Genetic variants were classified according to the American College of Medical Genetics and Genomics; only likely pathogenic or pathogenic variants were considered relevant for solved cases. Eighty-four patients (58.3% males; mean age 40.0 ± 17.9 years) from 71 families were included. Usher syndrome was the most frequent etiology (71.4%) followed by Polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract syndrome (6.0%), Autosomal dominant optic atrophy plus (4.8%) and cone-rod dystrophy and hearing loss (4.8%). Other less frequent etiologies included Alport syndrome (2.4%), Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (2.4%), Heimler syndrome (2.4%), Senior-Loken syndrome (1.2%), Waardenburg syndrome (1.2%), Maternally inherited diabetes and deafness (1.2%), and Stickler syndrome (1.2%). The overall diagnostic yield of deleterious variants in our deaf-blind cohort was 73.2%. A total of 55 genetic variants were identified across 16 different genes; 11 of these variants are novel and herein reported for the first time. This is the first study to describe the genetic profile of patients with dual sensory impairment in Portugal, highlighting the genetic heterogeneity associated with inherited deaf-blindness. Usher syndrome was the most prevalent cause in this cohort. Nevertheless, several other less frequent causes must also be considered. This study showed a high diagnostic yield and reported 11 novel genetic variants, thereby contributing to expand the mutational spectrum of these conditions.