Frequencies of trinucleotide repeats of the FRAXA and FRAXE gene in Korean populations

Abstract

[한글]

Frequencies of trinucleotide repeats of the FRAXA and FRAXE gene in Korean

populations

Eun-Sook Park

Department of Molecular Medicine The Graduate School, Yonsei University

(Directed by Associate Professor Jin-Sung Lee)

The frequent form of inherited mental retardation, Fragile X syndrome is

associated with FRAXA, and mild form of mental handicap is associated with FRAXE.

The fragile sites of FRAXA and FRAXE, located approximately 600kb apart on Xq27.3

and Xq28 respectively, are due to a trinucleotide repeat expansion (CGG/GCC) within

the 5'UTR region of the FMR1 and FMR2 gene.

The evaluation of triplet repeats in normal individuals is important for

diagnosis of X-linked mental retardation; however, the number of triplet repents at

FRAXA and FRAXE has not yet been reported in the Korean population. In order to

evaluate the diagnostic criteria for the diseases in Korean population, we measured

the number of trinucleotide repeats at FRAXA and FRAXE in normal individuals using

PCR. In the FRAXA we found that the number of CGG repeats in 339 normal individuals

(in total439 X chromosomes) ranged from 19 to 50 repeats. In the FRAXE the number

of GCC repeats in 195 normal individuals (in total 260 X chromosomes) was between 4

to 22 repeats. The range of trinucleotide repeats observed in normal individuals in

this study was not so different from that of Western population.

The frequency of trinucleotide repeats in normal individuals will be useful for

carrier screening and prenatal diagnosis as well as diagnosis of X-linked mental

retardation in practice.

[영문]

The frequent form of inherited mental retardation, Fragile X syndrome is associated with FRAXA, and mild form of mental handicap is associated with FRAXE.

The fragile sites of FRAXA and FRAXE, located approximately 600kb apart on Xq27.3 and Xq28 respectively, are due to a trinucleotide repeat expansion (CGG/GCC) within the 5'UTR region of the FMR1 and FMR2 gene.

The evaluation of triplet repeats in normal individuals is important for diagnosis of X-linked mental retardation; however, the number of triplet repents at FRAXA and FRAXE has not yet been reported in the Korean population. In order to evaluate the diagnostic criteria for the diseases in Korean population, we measured the number of trinucleotide repeats at FRAXA and FRAXE in normal individuals using PCR. In the FRAXA we found that the number of CGG repeats in 339 normal individuals (in total439 X chromosomes) ranged from 19 to 50 repeats. In the FRAXE the number of GCC repeats in 195 normal individuals (in total 260 X chromosomes) was between 4 to 22 repeats. The range of trinucleotide repeats observed in normal individuals in this study was not so different from that of Western population.

The frequency of trinucleotide repeats in normal individuals will be useful for carrier screening and prenatal diagnosis as well as diagnosis of X-linked mental retardation in practice.