PCR products from different reactions were combined, 1 Al from the mixture was added to 1.5 Al formamide-loading buffer and 0.5 Al MapMarkerk 400 TMR standard ladder (Bio Ventures, Murfreesboro, TN, USA).
After denaturation at 92 jC for 2 min, 1 Al of the solution was loaded onto an acrylamide gel (4%) in an ABI-377 DNA sequencer (Applied Biosystems).
The DNA fragments were separated by electrophoresis and automatically sized by comparison with the internal standard using Genescan software (version 3.1).
Genotypes of individual samples were determined by Genotyper software (version 2.0) and automatically exported to a database.