A Sphingosine-1-Phosphate Lyase Mutation Associated With Congenital Nephrotic Syndrome and Multiple Endocrinopathy

• Main Authors: Avinaash Maharaj, Demetria Theodorou, Indraneel (Indi) Banerjee, Louise A. Metherell, Rathi Prasad, Dean Wallace
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2020-04-01
• Series: Frontiers in Pediatrics
• Subjects: SGPL1; sphingosine-1-phosphate lyase; congenital nephrotic syndrome; primary adrenal insufficiency; multiple endocrinopathy
• Online Access: https://www.frontiersin.org/article/10.3389/fped.2020.00151/full

Background: Loss of function mutations in SGPL1 are associated with Sphingosine-1-phosphate lyase insufficiency syndrome, comprising steroid resistant nephrotic syndrome, and primary adrenal insufficiency (PAI) in the majority of cases. SGPL1 encodes sphingosine-1-phosphate lyase (SGPL1) which is a major modulator of sphingolipid signaling.Case Presentation: A Pakistani male infant presented at 5 months of age with failure to thrive, nephrotic syndrome, primary adrenal insufficiency, hypothyroidism, and hypogonadism. Other systemic manifestations included persistent lymphopenia, ichthyosis, and motor developmental delay. Aged 9 months, he progressed rapidly into end stage oligo-anuric renal failure and subsequently died. Sanger sequencing of the entire coding region of SGPL1 revealed the novel association of a rare homozygous mutation (chr10:72619152, c.511A>G, p.N171D; MAF−1.701e-05) with the condition. Protein expression of the p.N171D mutant was markedly reduced compared to SGPL1 wild type when overexpressed in an SGPL1 knockout cell line, and associated with a severe clinical phenotype.Conclusions: The case further highlights the emerging phenotype of patients with loss-of-function SGPL1 mutations. Whilst nephrotic syndrome is a recognized feature of other disorders of sphingolipid metabolism, sphingosine-1-phosphate lyase insufficiency syndrome is unique amongst the sphingolipidoses in presenting with multiple endocrinopathies. Given the multi-systemic and progressive nature of this form of PAI/ nephrotic syndrome, a genetic diagnosis is crucial for optimal management and appropriate screening for comorbidities in these patients.