Genetic typing by capillary electrophoresis with the allelic ladder as an absolute standard

We demonstrate a genetic typing method based on capillary electrophoresis/laser-induced fluorescence (CE-LIF). VNTR polymorphism in the human D1S80 locus was studied. A pooled allelic ladder, which contains the 27 most common human alleles, was used as the absolute standard. Extracted genomic DNA from an individual was amplified by polymerase chain reaction (PCR). Typing can be accomplished by co-injection of the PCR product and the D1S80 ladder and then running CE. Separation by a polymer solution of poly(ethylene oxide) in uncoated fused-silica capillaries allows high-resolution, repeated runs in the same capillary. Sensitive detection with minimal sample preparation is possible by using ethidium bromide as the intercalating dye. Statistical analysis of the data indicates a high level of confidence in matching the bands despite variations in the injection process or in the CE system. Future adaptation to a multiple-capillary array system should allow high-speed, high-throughput operation.