HPSE2 and Ochoa syndrome: Some families with UFS have biallelic variants in heparanase 2 (HPSE2)8, 9, 10 encoding heparanase 2, an inhibitor of the enzyme activity of the classical heparanase protein,11 hereafter called “heparanase.” Homozygous Hpse2 gene-trap mice have incomplete bladder emptying,10, 12 phenocopying UFS.