A polymorphic STS in intron 44 of the dystrophin gene.

A 300-bp EcoRV polymorphism, detected with P20 (DXS269) in intron 44 of the human dystrophin gene, is due to an insertion or deletion. To make this restriction fragment length polymorphism (RFLP) available for polymerase chain reaction (PCR) analysis, we sequenced both alleles of this polymorphism and synthesized primers flanking the mutation site. The origin of the mutation is a single Alu repeat insertion. The 300-bp polymorphism can now be successfully detected by PCR and provides an excellent tool to detect female carriers in this deletion prone region of the dystrophin gene.