Acid sphingomyelinase-like phosphodiesterase 3b (SMPDL-3b) plays a role in the conversion of sphingomyelin to ceramide by acid sphingomyelinase (ASMase) and its levels are reduced in renal biopsy specimens from patients with recurrent focal segmental glomerulosclerosis (FSGS). The gene discussed is SMPD1; the disease is focal segmental glomerulosclerosis.