DNA TYPING OF HUMAN-LEUKOCYTE ANTIGEN SEQUENCE POLYMORPHISMS BY PEPTIDE NUCLEIC-ACID PROBES AND MALDI-TOF MASS-SPECTROMETRY

A novel analytical method using PNA probes detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-T OFMS) was applied to type sequence polymorphisms within the human leuk ocyte antigen (HLA), DQA locus. Streptavidin-coated magnetic beads wer e used to immobilize biotinylated DNA. PNA probes representing possibl e alleles were then prepared for the immobilized DNA hybridization, Th e nonspecific PNA probes were removed with stringent washes. The PNA/D NA/beads conjugate was analyzed by MALDI-TOFMS. The genotype of the DN A was determined by the detected molecular masses of the released PNA probes. Reproducible and accurate genotyping was achieved by this anal ytical method.