The
Affymetrix CNAT Input Engine
imports multiple CNAT4.0 files into a single SAS data set, with rows representing individual
SNPs
, and columns containing various copy number or loss-of-heterozygosity measurements, for each of the samples.
Each
.CNT
file is a tab-delimited text file and corresponds to an individual
microarray
. Its header contains specific information about the format of the chip. Below the header are columns identifying specific spots along with their copy number (CN) or loss-of-heterozygosity (LOH) estimates and statistics. An example of one such file is shown below.
.CNT
files typically occur in pairs. Both files in a pair share the same name but have different suffixes appended. One file in the pair lists
copy number
(CN) data and has the
.cn.cnt
suffix. The other lists
loss-of-heterozygosity
(LOH) data and has the
.loh.cnt
suffix.
The following example uses a subset of the 500K HapMap Normal data set available for download from
Affymetrix
. Compressed files containing LOH and CN data from three samples, each on both Nsp and Sty arrays, were downloaded from the
Affymetrix website
, unzipped, and saved to a folder named
CNAT
in the
Genomics\Sample Data
folder. Included files are listed below.