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. 1999 Jun 22;13(4):188–193. doi: 10.1002/(SICI)1098-2825(1999)13:4<188::AID-JCLA8>3.0.CO;2-G

Application of FTA® sample collection and DNA purification system on the determination of CTG trinucleotide repeat size by PCR‐based southern blotting

Kuang‐Ming Hsiao 1, Her‐Maw Lin 2, Huichin Pan 1, Tung‐Cheng Li 2, Sung‐Sheng Chen 5, Shuo‐Bin Jou 6, Ya‐Lan Chiu 3, Ming‐Fang Wu 1, Chyi‐Chyang Lin 1,4, Shuan‐You Li 1,✉
PMCID: PMC6807929  PMID: 10414599

Abstract

Myotonic dystrophy (DM) is caused by a CTG trinucleotide expansion mutation at exon 15 of the myotonic dystrophy protein kinase gene. The clinical severity of this disease correlates with the length of the CTG trinucleotide repeats. Determination of the CTG repeat length has been primarily relied on by Southern blot analysis of restriction enzyme‐digested genomic DNA. The development of PCR‐based Southern blotting methodology provides a much more sensitive and simpler protocol for DM diagnosis. However, the quality of the template and the high (G+C) ratio of the amplified region hamper the use of PCR on the diagnosis of DM. A modified PCR protocol to amplify different lengths of CTG repeat region using various concentrations of 7‐deaza‐dGTP has been reported (1). Here we describe a procedure including sample collection, DNA purification, and PCR analysis of CTG repeat length without using 7‐deaza‐dGTP. This protocol is very sensitive and convenient because only a small number of nucleate cells are needed for detection of CTG expansion. Therefore, it could be very useful in clinical and prenatal diagnosis as well as in prevalence study of DM. J. Clin. Lab. Anal. 13:188–193, 1999. © 1999 Wiley‐Liss, Inc.

Keywords: myotonic dystrophy, CTG trinucleotide repeat, DM diagnosis, PCR, FTA® Gene Guard System

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