PURPOSE:The lesion of Congenital Lipoid Adrenal Hyperplasia has been suggested to be in the 1st step of steroidogenesis of conversion of cholesterol to pregnenolone by P450scc. In 1995, however, the molecular defect of this disease has been located in the transport of cholesterol into mitochondria due to defective regulatory protein called Steroidogenic Acute Regulatory Protein(StAR), while the enzyme P450scc itself is normal. This genetic study using automatic sequence analyzer aimed at elucidating the molecular defect in the StAR gene of the two patients. METHODS:This study was performed on the two patients of Congenital Lipoid Adrenal Hyperplasia. Both children were phenotypically females. However, one turned out to have a karyotype of 46, XY, the other 46, XX. Genomic DNAs were extracted from their peripheral blood. We amplified the last exon, hot spot, of the StAR gene using 1 set of primer, S4, 5'-CCT GGC AGC CTG TTT GTG ATA G-3' AS4, 5'-CCT CAT GTC ATA GCT AAT CAG TG-3'. Subsequently, one PCR product have been directly sequenced by dideoxy termination method, and also the other products(patient's and her father's) have been sequenced by automatic sequence analyzer. RESULTS:The mutation was identified in the last exon of the StAR gene, substituting T for A at codon 258, replacing glutamine by stop codon in the two unrelated Korean patients with congenital lipoid adrenal hyperplasia. One patient were found to be homozygote, but the other to be heterozygote for the mutation. CONCLUSIONS:These results indicate that Korean children with congenital lipoid adrenal hyperplasia may be genetically identical as in Japanese. But, we discovered that the hot spot, codon 258, are not always homozygote. We want to emphasize the different point, and to say that we did experiece the automatic sequence analyzer successfully.