Rapid method to characterize mutations in transthyretin in cerebrospinal fluid from familial amyloidotic polyneuropathy patients by use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
BACKGROUND
Familial amyloidotic polyneuropathy (FAP) type I, the most common dominantly inherited form of amyloidosis, is caused by a Val-to-Met point mutation at position 30 (Val(30)-->Met) in the protein transthyretin. Mass spectrometric analysis can identify modification of proteins, such as point mutations, acetylation, phosphorylation, sulfation, oxidation, and glycosylation.


METHODS
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) spectra from cerebrospinal fluid (CSF) drawn from a patient with FAP were compared with CSF from controls. We also isolated transthyretin with a Centrisart molecular size cutoff filter and performed high-accuracy peptide mass mapping to localize the site of the amino acid substitution (Val(30)-->Met).


RESULTS
Mass spectra of transthyretin were produced directly from human CSF as well as from CSF after a simple prepurification method without immunoprecipitation. On-target tryptic digestion and MALDI-MS verified mass spectrometric peak identification. The point mutation was still detectable in CSF after hepatic transplantation.


CONCLUSIONS
It is possible to diagnose FAP by a rapid MALDI-TOF MS analysis using only 100 microL of CSF, with only 250 nL actually consumed on target. The approach may also be useful to monitor production of mutated transthyretin by choroid plexus, especially after liver transplantation.
Bergquist
J
J
Institute of Clinical Neuroscience, Department of Psychiatry and Neurochemistry, and Department of Neurology, Göteborg University, Sahlgrenska University Hospital, SE-43/80 Mölndal, Sweden. jonas.bergquist@kemi.uu.se
Andersen
O
O
Westman
A
A
D000328:Adult; D017772:Amyloid Neuropathies / Q000134:cerebrospinal fluid / Q000235:genetics*; D005260:Female; D006801:Humans; D017354:Point Mutation; D011228:Prealbumin / Q000134:cerebrospinal fluid / Q000235:genetics*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D011228:Prealbumin