Detection of different forms of variant transthyretin (Met30) in cerebrospinal fluid

To detect the variant transthyretin (TTR; Met30) in cerebrospinal fluid (CSF) of familial amyloidotic polyneuropathy (FAP) patients, we have applied a new method using a centrifugal concentrator device and electrospray ionization mass spectrometry (ESI-MS). Only 100 microl of CSF and 30 microl of the antibody for TTR was needed for the analysis. After preparation of the samples with anti-TTR antibody, they were passed through a 1000 kDa cut-off centrifugal concentrator which retained the antibody. By analyzing the obtained filtrate with ESI-MS, three predominant forms of normal and their variant forms of TTR were detected in CSF samples. TTR (Met30), with a molecular weight 32.0 Da higher than the normal form of TTR, was found in all FAP patients' materials. Although the ratio of the three major peaks of TTR were different in each individual, they were always found in CSF and sera. This method will contribute to make a diagnosis of neurologic disorders having a mutant protein in CSF as well as serum.