Tau assay

The method according to any previous claim wherein the reference peptides comprises one or more peptides each comprising an amino acid sequence independently selected from SEQ ID NO:

• 43 to SEQ ID NO:
• 78.

The method according to any previous claim wherein the precursor reference peptides comprises one or more peptides each comprising an amino acid sequence independently selected from SEQ ID NO:

• 79 to SEQ ID NO:
• 186.

The method according to any previous claim wherein the reference polypeptides comprises one or more polypeptides selected from Table 7.

The method according to any previous claim wherein the at least one protease is trypsin, optionally in combination with Lys-C and/or AspN.

The method according to any previous claim, wherein at least one of the one or more target proteolytic peptides comprises the sequence DEAAGHVTQAR (SEQ ID NO:

• 25) and/or the sequence VQIVYKPV (SEQ ID NO:
• 26) and wherein the subtype is the Microtubule Associate Protein Tau expressed by the Central Nervous System.

The method according to any previous claim, wherein at least one of the one or more reference peptides, precursor reference peptides or reference polypeptides comprise heavy isotopes.

The method according to any preceding claim, wherein the step of preparing a biological sample from the subject by isolating target proteins from the sample includes enrichment of the target proteins.

The method according any of the preceding claims wherein the reference polypeptides are recombinant versions of the target proteins.

The method according any of the preceding claims wherein the reference peptides, precursor reference peptides or polypeptides are synthetic peptides.

The method according any of the preceding claims wherein the biological sample from the subject is Whole Blood, Blood Plasma, Serum or Saliva.

A method for diagnosing and/or classifying the severity of a neurodegenerative disease in a subject, the method comprising:

• (i) determining the absolute quantity of Central Nervous System Tau according to any one of the previous claims:
• (ii) diagnosing and/or classifying the severity of the neurodegenerative disease of the subject according to the absolute quantity of Central Nervous System Tau.

The method according any of the preceding claims, wherein the Neurodegenerative disease is Alzheimer's disease.

A kit for diagnosing and/or classifying the severity of a Neurodegenerative disease in a subject, comprising:

• a plurality of sample preparation media for analysis of a biological sample from a subject by mass spectrometry for the presence of at least one target proteolytic peptide selected from the group of peptides from subtypes of Microtubule Associated Protein Tau Expressed by the Central Nervous System, subtypes of Microtubule Associated Protein Tau Expressed by the Peripheral Nervous System and peptides that are common to all subtypes of Microtubule Associated Protein Tau.

A kit for use in the treatment of a subject with a Neurodegenerative disease, wherein the kit comprises:

• a plurality of sample preparation media for analysis of a biological sample from a subject by mass spectrometry for the presence of at least one target proteolytic peptide selected from the group of peptides from subtypes of Microtubule Associated Protein Tau Expressed by the Central Nervous System, subtypes of Microtubule Associated Protein Tau Expressed by the Peripheral Nervous System and peptides that are common to all subtypes of Microtubule Associated Protein Tau.;
• and
• a therapeutic agent for treatment of a Neurodegenerative disease.

A kit for assessing the efficacy of a treatment for a neurodegenerative disease in a subject, wherein the kit comprises:

• a plurality of sample preparation media for analysis of a biological sample from a subject by mass spectrometry for the presence of at least one target proteolytic peptide selected from the group of peptides from Subtypes of Microtubule Associated Protein Tau Expressed by the Central Nervous System, Subtypes of Microtubule Associated Protein Tau Expressed by the Peripheral Nervous System and peptides that are common to all Subtypes of Microtubule Associated Protein Tau.