BACKGROUND: Tandem duplication of chromosome 17p11.2-p12 including peripheral myelin protein 22 (PMP22) gene is the most frequent cause of Charcot-Marie-Tooth 1A (CMT1A). Patients carrying one extra copy of PMP22 develop CMT1A, whereas the deletion of the 17p11.2-p12 region causes hereditary neuropathy with the liability to pressure palsies (HNPP). In the present study, we established the genotyping methods of 6 microsatellite markers (D17S921, D17S9B, D17S9A, D17S4A, D17S918 and D17S122) within the 17p11.2-p12 regions by the hexaplex PCR for the genetic diagnosis of CMT1A duplication and HNPP deletion. METHODS: We established polymorphic behavior and genotyping methods of 6 microsatellite markers (D17S921, D17S9B, D17S9A, D17S4A, D17S918 and D17S122) within the duplication region. The 6 markers were amplified by hexaplex PCR reaction and analyzed by an automatic sequencing analyzer and genotyper program. RESULTS: The genotype distributions of all markers were not significantly deviated from the Hardy-Weinberg equilibrium (P>or=0.05). When comparing the control group and CMT1A, HNPP patients group by the distribution of allele, there is no significant difference in the 5 locus except in the 1 locus (D17S921) among HNPP patients. The specificity was more than 99.9%. The sensitivity of each CMT1 and HNPP was 56.3% (40/71 pedigrees) and 72.1% (31/43 HNPP pedigrees), respectively. CONCLUSIONS: The error rate for the system may be less than 0.001. According to this study, it is possible to have rapid and exact genetic diagnosis of both CMT1A and HNPP, which may be helpful for the development of personalized therapy according to genetic defects.