A fast modified protocol for random-access ultra-high density whole-genome scan: a tool for personalized genomic medicine, positional mapping, and cytogenetic analysis.

Background: High density single nucleotide polymorphism (SNP) genotyping array is widely applied on genome-wide association study of common diseases. In these studies, a fixed batch-size of 48 or 96 samples allows high-throughput analysis. To enhance the clinical application of microarray analysis on personalized medicine, we describe a modified PCR purification protocol without batch-size limitation for whole-genome scan using ultra-high density SNP microarray.

Methods: Enzyme-digested PCR products were purified with the use of magnetic beads. Separation of the magnetic particles applies magnetic stand devices instead of vacuum pumps. With no batch-size limitation, we genotyped 17 genomic samples and 3 whole genome amplified samples in order to examine the performance of the modified protocol.

Results: Our method is simple and fast, provides sufficient amount and high quality PCR products for subsequent fragmentation and labeling procedures prior to GeneChip hybridization. We show that the purified DNA can be genotyped with good QC call rate of >93% in average similar to standard protocol. With the use of the short protocol, we successfully identified the breakpoint localization of a ring chromosome in a female and located the disease gene in a consanguineous family affected by limb-girdle muscular dystrophy.

Conclusion: By modifying a single step in the original protocol, we are able to speed up the overall genotyping analysis and change the batch-wise analysis to random-access analysis for ultra-high density whole-genome scan for personalized medicine, positional mapping, and cytogenetic analysis.