High throughput screening for expanded CTG repeats in myotonic dystrophy type 1 using melt curve analysis
Russell J Butterfield1,2, Carina Imburgia1, Katie Mayne1
1Department of Pediatrics, University of Utah, Salt Lake City, Utah, USA.
Molecular Genetics & Genomic Medicine
|February 24, 2021
Summary
A new screening tool accurately detects CTG repeat expansions in myotonic dystrophy type 1 (DM1) using triplet-primed PCR and melt curve analysis. This low-cost method is suitable for large-scale newborn screening and population studies.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy, caused by CTG repeat expansions in the DMPK gene.
- Diagnosis is often delayed due to nonspecific symptoms overlapping with other conditions.
- Current genetic testing methods are complex and expensive for population-wide screening.
Purpose of the Study:
- To develop a high-throughput, cost-effective screening tool for CTG repeat expansions.
- To enable early detection of DM1 in large populations.
Main Methods:
- Utilized triplet-primed PCR (TP-PCR) combined with high-resolution melt curve analysis.
- Employed saturating concentrations of SYBR GreenER dye for sensitive detection.
- Applied the method to screen 10,097 newborn blood spots.
Main Results:
- Multimodal melt profiles from TP-PCR accurately indicated amplicon length and stoichiometry.
- The assay successfully identified common alleles (5-35 CTG repeats) and detected premutation and full expansion alleles.
- Robust detection was achieved even with minimal DNA from dried blood spots.
Conclusions:
- Developed a reliable, single-tube method for detecting expanded CTG repeats.
- The technique is adaptable for large-scale genetic testing programs, including newborn screening.
- Facilitates efficient and accessible screening for myotonic dystrophy type 1.
