RESUMEN
OBJECTIVE: The purpose of this investigation was to establish the prenatal diagnosis for identifying the risk for epidermolytic palmoplantar keratoderma(EPPK) of a fetus by sequence analysis of fetal genomic DNA from chorionic villi. METHODS: Chorionic villus sampling under transvaginal sonography at 12 weeks of gestation from a woman at risk for a child in a EPPK-affected family was perfomed. Polymerase chain reaction amplification of specific allele (PASA) assay was carried out for the detection of mutation(R162W in keratin 9 [K9] gene) previously identified in this family. Direct DNA sequencing analysis of K9 gene was accomplished to confirm the mutation. RESULTS: We had found the point mutation, R162W of K9 gene, in affected family members and confirmed by PASA assay. Affected family members were shown to have PCR products reactive with both the mutant and wildtype specific primers. Because we could not find any expected products after PASA assay with the primers la(+)/KSmt(-) of the fetal DNA, we predicted that the fetus did not inherited the mutant allele and that the fetus could be unaffected. After PASA assay, we analyzed DNA sequences of two family members to confirm the mutation. A C-to-T substitution at bp 545 was detected in the father, instead the fetus did not have any mutant band at that base pair. CONCLUSION: The PASA assay and direct DNA sequencing analysis of K9 gene through chorionic villi sampling and extraction of genomic DNA had validity to early prenatal diagnosis whether fetus was affected in EPPK or not.