Patterns of loss of heterozygosity and copy number variation in 30 ESCC samples for chromosome 3. Each row (numbered 1 - 30) represents an individual ESCC sample. Circles indicate the positions of SNPs showing LOH. SNP positions are color coded as follows: black indicates copy number neutral LOH; blue indicates LOH accompanied by copy number reduction; red indicates LOH with copy number gain. An ideogram of the chromosome is at the bottom of the figure.