Methods of diagnosing mucopolysaccharidosis (MPS) I and methods of monitoring treatment of MPS by quantifying a non-reducing end glycan residual compound and comparing to a second biomarker

1. A method of determining in an individual the presence, identity, and/or severity of mucopolysaccharidosis (MPS) I, the method comprising:

(a) generating a first biomarker comprising a glycan residual compound, wherein the first biomarker is generated by treating a population of glycans, in or isolated from a biological sample from the individual, with at least one digesting glycan enzyme, wherein prior to enzyme treatment, the first biomarker is not present in abundance in samples from individuals with MPS I relative to individuals without MPS I, and wherein the first biomarker is a non-reducing end (NRE) biomarker;

(b) generating a second biomarker comprising a glycan residual compound, wherein the second biomarker is generated by treating a population of glycans, in or isolated from a biological sample from the individual, with at least one digesting glycan enzyme,

wherein prior to enzyme treatment, the second biomarker is not present in abundance in samples from individuals with the MPS I relative to individuals without the MPS I, and wherein:

1) the second biomarker is a reducing end biomarker,

2) the second biomarker is an internal glycan biomarker, or

3) when the MPS I is caused by an abnormal function of a glycan degradation enzyme in the individual, the second biomarker is generated by treating the first biomarker with the glycan degradation enzyme that is functioning abnormally in the individual;

(c) detecting the presence of and/or measuring the amount of the first and second biomarker produced and displaying or recording the presence of or a measure of a population of the first and second biomarkers by using an analytical instrument; and

(d) monitoring and/or comparing the amounts of the first and second biomarkers in a biological sample;

wherein the presence of and/or measure of the amounts of the first and second biomarkers are utilized to determine the presence, identity, and/or severity of MPS I.

2. The method of claim 1 , wherein the population of glycans comprises a glycan selected from the group consisting of chondroitin sulfate, dermatan sulfate, and heparan sulfate.

3. The method of claim 1 , wherein the first biomarker is selected from the group consisting of IdoA-GlcNS, IdoA-GlcNS6S, IdoA-GlcNAc, and IdoA-GlcNAc6S.

4. The method of claim 3 , wherein the first biomarker is IdoA-GlcNS.

5. The method of claim 1 , wherein the second biomarker is selected from the group consisting of ΔUA-GlcN, ΔUA-GlcN6S, ΔUA2S-GlcN, ΔUAS-GlcN6S, ΔUA-GlcNAc, ΔUA-GlcNAc6S, ΔUA2S-GlcNAc, ΔUA2 S-GlcNAc6S, ΔUA-GlcNS, ΔUA-GlcNS6S, ΔUA-GlcNS3 S, ΔUA2S-GlcNS, ΔUA2S-GlcNS6S, ΔUA2S -GlcNS3S, ΔUA-GlcNS6S3S, and ΔUA2S-GlcNS6S3S.

6. The method of claim 5 , wherein the second biomarker is selected from the group consisting of ΔUA-GlcNAc and ΔUA-GlcNS.

7. The method of claim 1 , wherein the first biomarker is selected from the group consisting of IdoA-GlcNS, IdoA-GlcNS6S, IdoA-GlcNAc, and IdoA-GlcNAc6S, and the second biomarker is selected from the group consisting of ΔUA-GlcN, ΔUA-GlcN6S, ΔUA2S-GlcN, ΔUAS-GlcN6S, ΔUA-GlcNAc, ΔUA-GlcNAc6S, ΔUA2S-GlcNAc, ΔUA2 S-GlcNAc6S, ΔUA-GlcNS, ΔUA-GlcNS6S, ΔUA-GlcNS3 S, ΔUA2S-GlcNS, ΔUA2S-GlcNS6S, ΔUA2S-GlcNS3 S, ΔUA-GlcNS6S3S, and ΔUA2S-GlcNS6S3S.

8. The method of claim 7 , wherein the first biomarker is IdoA-GlcNS.

9. The method of claim 7 , wherein the second biomarker is selected from the group consisting of ΔUA-GlcNAc, and ΔUA-GlcNS.

10. The method of claim 7 , wherein the first biomarker is IdoA-GlcNS and the second biomarker is selected from the group consisting of ΔUA-GlcNAc and ΔUA-GlcNS.

11. The method of claim 1 , wherein the first biomarker is selected from the group consisting of IdoA-GalNAc4S, IdoA-GalNAc6S, IdoA-GalNAc, and IdoA-GalNAc4S6S, and the second biomarker is selected from the group consisting of ΔUA-GalNAc, ΔUA-GalNAc4S, ΔUA-GalNAc6S, ΔUA2S-GalNAc, ΔUA2S-GalNAc4S, ΔUA2S-GalNAc6S, ΔUA-GalNAc4S6S, and ΔUA2S-GalNAc4S6S.

12. The method of claim 11 , wherein the first biomarker is IdoA-GalNAc and the second biomarker is selected from the group consisting of ΔUA-GalNAc and ΔUA-GalNAc4S.

13. The method of claim 1 , wherein the first biomarker is selected from the group consisting of IdoA-GlcNS, IdoA-GlcNS6S, IdoA-GlcNAc, and IdoA-GlcNAc6S, and the second biomarker is selected from the group consisting of ΔUA-GalNAc, ΔUA-GalNAc4S, ΔUA-GalNAc6S, ΔUA2S-GalNAc, ΔUA2S-GalNAc4S, ΔUA2S-GalNAc6S, ΔUA-GalNAc4S6S, and ΔUA2S-GalNAc4S6S.

14. The method of claim 13 , wherein the first biomarker is IdoA-GlcNS.

15. The method of claim 13 , wherein the first biomarker is IdoA-GlcNS, and the second biomarker is selected from the group consisting of ΔUA-GalNAc and ΔUA-GalNAc4S.

16. The method of claim 1 , wherein the first biomarker is selected from the group consisting of IdoA-GalNAc4S, IdoA-GalNAc6S, IdoA-GalNAc, and IdoA-GalNAc4S6S, and the second biomarker is selected from the group consisting of ΔUA-GlcN, ΔUA-GlcN6S, ΔUA2S-GlcN, ΔUAS-GlcN6S, ΔUA-GlcNAc, ΔUA-GlcNAc6S, ΔUA2S-GlcNAc, ΔUA2S-GlcNAc6S, ΔUA-GlcNS, ΔUA-GlcNS6S, ΔUA-GlcNS3S, ΔUA2S-GlcNS, ΔUA2S-GlcNS6S, ΔUA2S-GlcNS3S, ΔUA-GlcNS6S3S, and ΔUA2S-GlcNS6S3S.

17. The method of claim 16 , wherein the first biomarker is IdoA-GalNAc and the second biomarker is selected from the group consisting of ΔUA-GlcNAc, and ΔUA-GlcNS.

18. The method of claim 1 , wherein the at least one digesting glycan enzyme is iduronidase.

19. A method of determining in an individual the presence, identity, and/or severity of mucopolysaccharidosis (MPS) I, the method comprising:

(a) generating a first biomarker comprising a glycan residual compound, wherein the first biomarker is generated by treating a population of glycans, in or isolated from a biological sample from the individual, with at least one digesting glycan enzyme, wherein prior to enzyme treatment, the first biomarker is not present in abundance in samples from individuals with MPS I relative to individuals without MPS I, and wherein the first biomarker is a non-reducing end (NRE) biomarker;

(b) generating a second biomarker comprising a glycan residual compound, wherein the second biomarker is generated by treating a population of glycans, in or isolated from a biological sample from the individual, with at least one digesting glycan enzyme,

wherein prior to enzyme treatment, the second biomarker is not present in abundance in samples from individuals with the MPS I relative to individuals without the MPS I, and wherein:

1) the second biomarker is an NRE biomarker different from the first biomarker,

2) the second biomarker is a reducing end biomarker,

3) the second biomarker is an internal glycan biomarker, or

4) when the MPS I is caused by an abnormal function of a glycan degradation enzyme in the individual, the second biomarker is generated by treating the first biomarker with the glycan degradation enzyme that is functioning abnormally in the individual;

(c) detecting the presence of and/or measuring the amount of the first and second biomarker produced and displaying or recording the presence of or a measure of a population of the first and second biomarkers by using an analytical instrument; and

(d) monitoring and/or comparing the amounts of the first and second biomarkers in a biological sample;

wherein the presence of and/or measure of the amounts of the first and second biomarkers are utilized to determine the presence, identity, and/or severity of MPS I.

20. The method of claim 19 , wherein the first biomarker is IdoA-GalNAc and the second biomarker is selected from the group consisting of ΔUA-GlcNAc, and ΔUA-GlcNS.

21. The method of claim 19 , wherein the first biomarker is selected from the group consisting of IdoA-GalNAc4S, IdoA-GalNAc6S, IdoA-GalNAc, and IdoA-GalNAc4S6S, and the second biomarker is selected from the group consisting of IdoA-GlcNS, IdoA-GlcNS6S, IdoA-GlcNAc, and IdoA-GlcNAc6S.