Pitzken, Felix

Purpose of review Sulfate is essential for the sulfation of proteoglycans to maintain cell function. The mechanisms regulating the ‘ins and outs’ of systemic sulfate balance remain incompletely understood. SLC26A1 is an anion exchanger expressed in the kidney. It has recently been identified as a key regulator of plasma sulfate homeostasis in humans. This review summarizes current insights into SLC26A1 function and its role in human diseases. Recent findings Slc26a1-knockout mouse models exhibit reduced plasma sulfate and abnormal sulfate and oxalate homeostasis, accompanied by augmented susceptibility to acetaminophen-induced liver injury and kidney stone disease, although findings on oxalate homeostasis are inconsistent. In humans, rare and common SLC26A1 variants are associated with hyposulfatemia, musculoskeletal abnormalities, and, in some cases, nephrolithiasis. Functional assays confirm disrupted sulfate and oxalate transport of damaging variants. However, the knockout mouse models have been incompletely characterized, and few patients with damaging SLC26A1 variants have been characterized regarding sulfate and oxalate homeostasis and associated diseases. Summary SLC26A1 emerges as a key regulator of sulfate homeostasis, with potential roles in hepatic detoxification, skeletal integrity, and kidney stone disease. Additional mouse models with tissue-specific gene deletion are needed to delineate the role of SLC26A1 in sulfate and oxalate homeostasis as well as disease pathogenesis. Identification of additional patients with damaging variants in SLC26A1 as well as larger population studies may help to elucidate causal relationships of SLC26A1 activity with clinical outcomes.