RESUMO
BACKGROUND: Fragile X syndrome is one of the most common causes of mental retardation. For its prevention, detection of premutation range CGG repeat in FMR1 gene is necessary. The aim of our study was to determine the prevalence of premutation range of CGG repeat in neonate, and to evaluate the possibility of screening test. METHODS: DNA were extracted from Guthrie paper blood spot, referred for neonatal metabolic screening test, collected during the period of March 1996 through August 1996, at Chunchon Sacred Heart Hospital. Then FMR1 gene involving CGG repeat was amplified by polymerase chain reaction, and then abnormal expansion of CGG were analyzed by agarose gel electrophoresis and digoxigenin labelled chemiluminescent detection method. RESULTS: Four cases among 669 PCR product were appeared to have abnormal CGG expansion and 3 out of the 4 cases were confirmed to have abnormal CGG repeat by chemiluminescent detection method. CONCLUSION: We found 3 premutation range CGG expansion with a prevalence of 1/233 in neonate. Although PCR based agarose gel electrophoresis alone is not suitable for screening test, it could be a useful tool for fragile X screening test in combination with chemiluminescent detection method.