Methods for quantitative determination of methylation density in a DNA locus
First Claim
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1. A method of calculating the relative methylation density for a target locus in a DNA sample, the method comprising,i. contacting a first portion of the DNA sample with a methylation-dependent restriction enzyme under partial digestion conditions where the resulting number of remaining intact copies of the locus is inversely proportional to the quantity of methylation at the locus;
- ii. quantitatively amplifying intact copies of the locus in the DNA sample after step i;
iii. identifying a cycle-threshold (Ct) value from step ii;
iv. quantitatively amplifying intact copies of the locus in a second portion of the genomic DNA that has not been cut by a restriction enzyme;
v. identifying a cycle-threshold (Ct) value from step iv; and
,vi. determining the relative methylation density for the target locus by calculating the difference (Δ
Ct) between the Ct from step iii and the Ct from step v, wherein 2|Δ
Ct| is proportional to the relative methylation density.
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Abstract
The present invention is a novel method of determining the average DNA methylation density of a locus of interest within a population of DNA fragments.
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Citations
19 Claims
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1. A method of calculating the relative methylation density for a target locus in a DNA sample, the method comprising,
i. contacting a first portion of the DNA sample with a methylation-dependent restriction enzyme under partial digestion conditions where the resulting number of remaining intact copies of the locus is inversely proportional to the quantity of methylation at the locus; -
ii. quantitatively amplifying intact copies of the locus in the DNA sample after step i; iii. identifying a cycle-threshold (Ct) value from step ii; iv. quantitatively amplifying intact copies of the locus in a second portion of the genomic DNA that has not been cut by a restriction enzyme; v. identifying a cycle-threshold (Ct) value from step iv; and
,vi. determining the relative methylation density for the target locus by calculating the difference (Δ
Ct) between the Ct from step iii and the Ct from step v, wherein 2|Δ
Ct| is proportional to the relative methylation density.
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2. A method for detecting methylation density in a locus of genomic DNA, the method comprising:
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a. contacting a first portion of the genomic DNA containing the locus with a methylation-dependent restriction enzyme under partial digestion conditions where the resulting number of remaining intact copies of the locus is inversely proportional to the quantity of methylation at the locus; b. quantifying the remaining intact copies of the locus in the first portion following step a; c. quantifying intact copies of the locus in a second portion of the genomic DNA that has not been cut by a restriction enzyme, wherein comparison of the quantity of intact copies of the locus in step b to the quantity of intact copies of the locus in step c allows for methylation density detection. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification