The present invention provides a method of determining, in a sample, the
proportion of a total amount of a molecule that is derived from
catabolism due to the presence of age-related molecular alterations on
the molecule, comprising: a) determining the total amount of the molecule
in the sample; b) determining the amount of the molecule in the sample
that contains D-aspartate; and c) calculating the proportion of the
amount of the molecule of step (b) relative to the total amount of the
molecule as determined in step (a), thereby determining the proportion of
the total amount of the molecule that is derived from catabolism due to
the presence of age-related molecular alterations in the molecule.
Further provided is a method of diagnosing a musculoskeletal, arthritic
or joint disorder in a subject and/or identifying a subject at risk for
developing such a disorder, comprising: a) measuring an amount of
D-aspartate and/or an advanced glycation end product in a sample of the
subject; and b) comparing the amount of D-aspartate and/or advanced
glycation end product in the sample of (a) with an amount of D-aspartate
and/or advanced glycation end product in a sample of a control subject,
whereby an increased amount of D-aspartate and/or advanced glycation end
product in the sample of the subject as compared to the amount of
D-aspartate and/or advanced glycation end product in the sample of the
control subject is diagnostic of a musculoskeletal, arthritic or joint
disorder in the subject and/or identifies a subject at risk of developing
such a disorder.
