ESPE Abstracts

Loss of function mutations in SGPL1 (sphingosine-1-phosphate lyase) give rise to a multisystemic syndrome with predominating features of primary adrenal insufficiency (PAI) and steroid resistant nephrotic syndrome. Retrospective analysis of our patient cohort and the wider literature also demonstrated primary gonadal insufficiency in a third of male patients with microphallus and bilateral cryptorchidism (all with concomitant adrenal disease and high mortality in infancy). Mortality is high in the condition overall (50% in childhood), with pubertal delay yet to be reported in surviving male patients. SGPL1 carries out irreversible breakdown of sphingosine-1-phosphate (S1P) and deficiency leads to accumulation of S1P and upstream sphingolipid intermediates, that are bioactive signalling molecules with roles in various cellular processes. We developed an in vitro model to study the impact of SGPL1 deficiency on gonadal steroidogenesis by generating CRISPR-engineered knock-out (KO) of Sgpl1 in the MA10 immortalised Leydig cell line, validated by Sanger sequencing and western blotting demonstrating loss of SGPL1 expression. In response to forskolin stimulation, KO cell lines produced significantly reduced levels of progesterone when compared to wild type (WT). This was associated with decreased steroidogenic enzyme STAR and CYP11A1 protein expression, both in unstimulated and forskolin stimulated conditions in the KO lines. MTT assays also demonstrated reduced cell proliferation in the KO Leydig cells. Transcriptomic analysis highlighted dysregulation of genes in cholesterol and wider lipid metabolism in addition to steroid biosynthesis providing further insight into possible underlying mechanisms of disease. Given current findings, SGPL1 deficiency should be considered in the differential diagnosis of 46XY infants with differences in sex development (DSD) and PAI. SGPL1 deficiency impairs lipid metabolism and steroidogenesis in Leydig cells and clinicians need to consider evolving gonadal disease in affected patients