Senior-Loken Syndrome: A Rare Cause of End Stage Kidney Disease in a Child

Dear Editor,

A 14-year-old boy, second-born from a third-degree consanguineous marriage, presented with joint pain in both lower limbs for 2 years. Examination showed pallor, no dysmorphic features, and height and weight <3^rd percentile. Oculomotor apraxia was present. Investigations revealed Hb: 5.0 g/dL, serum Ca/PO₄: 6.3/8.7 mg/dL, Alkaline Phosphatase (ALP): 2194U/L, intact parathyroid hormone (iPTH): 1207.2 ng/L, 25(OH)Vit D: 128.64 ng/mL, pH: 7.30, HCO₃: 18 mEq/L, and serum urea/creatinine: 256/6.6 mg/dL. Ultrasound kidney ureter bladder showed bilateral shrunken kidney. Fundus examination showed retinitis pigmentosa [Figure 1]. Senior-Loken syndrome (SLSN) due to chronic kidney disease and retinitis pigmentosa (R) was suspected. Whole exome sequencing showed IQCB1 (ENST00000310864.11): c.488-1G>A, homozygous, pathogenic, autosomal recessive variant (as per Human Genome Variation Society Classification) associated with Senior-Loken syndrome 5 (OMIM#609254), confirming the diagnosis. The child was administered maintenance hemodialysis, antihypertensive drugs, oral sodium bicarbonate, calcium, sevelamer, and calcitriol. Family genetic testing was not done due to financial constraints [Supplementary File].

Close

Figure 1:

Fundus examination (direct ophthalmoscopy) showing retinitis pigmentosa.

Export to PPT

SLSN is a rare autosomal recessive oculo-renal disease with a prevalence of 1:1,000,000.^1,2 The SLSN5 is caused by mutations in the NPHP5/ICQB1 gene, first identified by Otto et al.¹ in 2005. It was first concurrently described by Senior et al.³ and Loken et al.⁴ in 1961 as a combination of familial juvenile nephronophthisis and Leber congenital amaurosis. Few cases have emerged from India, of which only one has been genetically proven.⁵ Severe infantile, juvenile, and adolescent are the three clinical nephronophthisis types. Severe infantile is the most severe form, and juvenile is the most common. The age of onset is ∼5 years, as in this case. This letter intends to raise awareness that ocular involvement is the most common presenting complaint in this syndrome. Our patient suffered from difficulty in vision since 5 years of age and was misdiagnosed with myopia and prescribed spectacles.