All issues > Volume 38(11); 1995

Original Article

J Korean Pediatr Soc. 1995;38(11):1470-1475. Published online November 15, 1995.

Use of Fluorescent in Situ Hybridization to Evaluate the Number of Chromosomes in Buccal Smear Cells in Normal Newborn Infants

Byoung Chan BC Lee¹, Jee Yeon JY Song¹, So Young SY Kim¹, Hyun Hee HH Kim¹, Seunghoon Sh Han¹, Jong-In JI Byun¹, Wonbae Wb Lee¹, Kyong Su KS Lee¹

¹Department of Pediatrics, College of Medicine, Catholic University, Seoul, Korea

Abstract

Purpose
: The diagnosis for chromosomal anomality has been made by obtaining cells in metaphase from peripheral blood and fresh tissue culture. But this method is difficult to perform because somewhat invasive and necessary time for cell culture and staining(48-72hr). Recently, the method to find numerical abnormalities in, autosome and sex chromosome of adult buccal mucosal smear by FISH was developed. So chromosomal anomaly can be detected quickly, but reproducibility is poor. To establish the method of high reproducibility and to know whether it can be applied to neonate, we performed studies in normal neonate.
Methods
: Of the normal neonates delivered and admitted in our hospital, 5 male and 5 female neonates were selected randomly. After scraping and smear their buccal mucosal epithelium, we cleaved protein with pepsin and use digoxigenin-labeled a-satellite DNA probe(Oncor, USA) capable of binding to each centromeres of 7, X- and Y-chromosome in interphase.
Results
: After evaluating 200 nuclei from each buccal mucosal smear, with 7 chromosome specific centromere probe 2 signals were seen in 193.6¡¾2.8(96.8%) and with X chromosome specific centromere probe, 2 signals were seen in 192.2¡¾1.9(96.1%) in female neonates and 1 signal in 196.8¡¾2.7(98.4%) in male neonates. Expected signals were seen in over 96%. When confidence interval was 3SD, if 2 signals were expected, 1 signal permitted 10.1%, 3 signals permitted 2.2%, if 1 signal expected, 2 signals can be seen normal to 7.3%. There was no signal more than twice expected.
Conclusion
: Expected signals were seen in over 96% and up to 9.7% of 1 signal and 2.2% of 3 signals in chromosome 7, 10.1% of 1 signal and 2.0% of 3 signals in female X chromosome, 7.3% of 2 signals in male X chromosome and 5.3% of 2 signals in male Y chromosome to be normal range. FISH is a rapid, easy, sensitive and less traumatic method for the diagnosis of sex determination and aneuploidy.

Keywords :Buccal smear, Fluorescent in situ hybridization(FISH), DNA probes, Interphase cytogenetics