Diagnosis of HNF-1a mutations on a PNA zip-code microarray by single base extension

Abstract

In the present study, we exploited the superior features of peptide nucleic acids (PNAs) to develop an efficient PNA zip-code microarray for the detection of hepatocyte nuclear factor-1a (HNF-1a) mutations that cause type 3 maturity onset diabetes of the young (MODY).Amulti-epoxylinkercompoundwassynthesized and used to achieve an efficient covalent linking of amine-modified PNA to an aminated glass surface. PCR was performed to amplify the genomic regions containing the mutation sites. ThePCRproducts were then employed as templates in a subsequent multiplex single base extension reaction using chimeric primers with 30 complementarity to the specific mutation site and 50 complementarity to the respective PNA zip-code sequence on the microarray. The primers were extended by a single base at each corresponding mutation site in the presence of biotin-labeled ddNTPs, and the products were hybridized to the PNA microarray. Compared to the corresponding DNA, the PNA zip-code sequence showed a muchhigher duplex specificity for thecomplementary DNA sequence. The PNA zip-code microarray was finally stained with streptavidin-R-phycoerythrin to generate a fluorescent signal. Using this strategy, we were able to correctly diagnose several mutation sites in exon 2 of HNF-1a with a wild-type and mutant samples including a MODY3 patient. This work represents one of the few successful applications of PNA in DNA chip technology.