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Table 1 Relative sample amount for which methylation can be determined as function of quantity and age

From: A tissue biopsy-based epigenetic multiplex PCR assay for prostate cancer detection

tissue biopsy volume

sample age

# samples (% correctly analyzable)

sufficient input DNA

methylated copies of

GSTP1

APC

RASSF1

10 μm

> = 5 years

45 (60%)

67%

81%

81%

48%

<= 1 year

53 (72%)

87%

80%

86%

84%

20 μm

> = 5 years

45 (73%)

78%

90%

93%

81%

<= 1 year

53 (92%)

100%

91%

94%

93%

40 μm

> = 5 years

45 (82%)

93%

86%

88%

83%

 

<= 1 year

53 (92%)

100%

96%

90%

93%

  1. Samples eligible for downstream analyses have sufficient quantity and quality of input DNA. For methylation, only samples with sufficient DNA (over 63 ACTB copies) are considered. Samples are labeled methylated when exceeding .27, 26.8 or 25.8 copies for GSTP1, APC and RASSF1 respectively, as preliminary determined based on the results of Figure 1F, optimizing for maximal correlation with the presence of cancer foci. The percentage of correctly analyzable samples is the combination of sufficient input DNA and detectability of methylation signals of either assay, when methylation should have been detected.