not critical to the invention but p l and p r must hybridize to the flanking sequences l and r respectively or complementary strand thereof under stringent conditions conditions for stringent hybridization are known in the art for example one may use a solution of 5 u00d7 ssc and 50 formamide incubated at 42 u00b0 c preferably 50 u00b0 c or 65 u00b0 c to maximize the resolution of size differences at the locus it is preferable to chose a primer sequence that is close to the repeat sequence usually within at least about 100 nucleotides of the repeat more usually at least about 50 nucleotides and preferably at least about 25 nucleotides algorithms for the selection of primer sequences are generally known and are available in commercial software packages the primers will hybridize to complementary strands of chromosomal dna and will prime towards the repeat sequences so that the repeats will be amplified the primers will usually be at least about 18 nucleotides in length and usually not more than about 35 nucleotides in length primers may be chemically synthesized in accordance with conventional methods or isolated as fragments by restriction enzyme digestion etc the term u201c polymorphic u201d means that n the number of repeat motif m at a specific locus is variable in a population therefore the polymorphisms of a microsatellite are represented as the differences in the length of dna that lies between the flanking.