The amplification product was separated by 1% agarose gel electrophoresis (Eppendorf, Milan) and stained with Sybr Safe DNA gel stain (Promega, Madison, Wisconsin). UV transillumination was used to observe the image. HinfI (Promega, Madison, Wisconsin) was used for RFLP. The restriction product was analysed with 3% agarose gel electro‐ phoresis