<unk>  is a human disorder caused by mutations in<unk> -5-phosphate isomerase, an enzyme of the pentose<unk>  pathway. With only four diagnosed patients over a 27-year period, RPI deficiency is the second rarest disease known as of now, being beaten only by Fields Condition affecting three individuals, Catherine and Kirstie Fields, and one unknown person.
Ribose-5-phosphate isomerase deficiency
Triosephosphate isomerase deficiency
Arginine:glycine amidinotransferase deficiency
Adenine phosphoribosyltransferase deficiency
Glutaminase deficiency
Galactose-1-phosphate uridylyltransferase deficiency
Malonyl-CoA decarboxylase deficiency
Carbamoyl phosphate synthetase I deficiency