Analysis of Polymorphisms in Tyrosinase Exon

For all samples analysed, hybridisation and wash steps with an added pair of PNA probes (wild-type and variant) were performed separately for each of the four polymorphic positions, as was the subsequent MALDI-TOF MS analysis. The separate spectra obtained for each of the four polymorphic positions were then added together to give a final, composite mass spectrum for each sample. In order to initially optimise the hybridisation and wash conditions, control experiments were done using synthetic oligonucleotide targets containing sequences corresponding to the possible alleles at each of the four point mutation positions. 

A limitation of this approach lies in the fact that each set of PNA probes requires different wash conditions in order to obtain good discrimination between the wild- 

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