Question

S. Vogelstein et al. Investigated allelic deletions in colorectal tumors at three different chromosomal locations. The data is presented in Table 3. In 1988 the genes of significance located on 59, 189, and 17p had not yet been identified. What broad class of genes are most likely located in these regions of chromosome loss? Explain your reasoning Table 3. Allelic Deletions in Colorectal Tumors (modified from Vogelstein et al (1988)) Chromosome Adenoma Adenoma Class I Class II percent tumors with deletion Adenoma Class III (no analyzed) Carcinoma Chromosome 5g 0 (34) Chromosome 184 13 (23) Chromosome 17p 6 (32) 29 (17) 11 (18) 6 (18) 29 (14) 47 (17) 24 (17) 36 (58) 73 (56) 75 (60) • Number of tumors that were informative for one or more of the markers on the indicated chromosome. 6. Graph the data presented in Table 3 to create a figure that shows the percentage of each type of genetic abnormality (5q, 184, and 17p) found in each type of tumor (Classi, Class II, Class III and Carcinoma). Line or bar graphs are acceptable. Note that numbers in "" are number of tumors, not percentage. % Tumors with Alteration Class Adenoma Carcinomas Class II Adenoma Class III Adenoma

Answer 1

Colorectal cancers often show allelic loss of chromosomes 5q and 17p, regions where the tumor suppressor genes p53 and adenomatous polyposis coli are known to reside. ... 5q Deletion was found in 33% of informative cases, whereas 17p deletion was seen in 69% of informative cases