Allelic loss and gain, but not genomic instability, as the major somatic mutation in primary hepatocellular carcinoma.

To identify genetic abnormalities in primary hepatocellular carcinoma (HCC), we performed microsatellite analysis (MSA) on 60 Chinese HCC specimens. Utilizing a semi-quantitative MSA and 292 highly polymorphic markers spanning all 22 autosomes, we found that somatic allelic imbalance (AI) occurred frequently in HCC. To evaluate the nature of the AI, comparative genomic hybridization was performed on 20 HCC specimens. The combined use of these two methods revealed frequent allelic loss on 17p, 9p21-p23, 4q, 16q21-q23.3, 13q, 8p21-p23, and 6q24-q27, whereas there was frequent allelic gain on 1q, 17q, and 8q24. The region with the highest incidence of genomic imbalance was 17p13 (65%), followed by 9p21-p23 (55%), 4q (35-51%), 16q21-q23.3 (52%), 17p12 (49%), 13q (39-46%), 8p21-p23 (41-45%), 8q24 (41%), and 1q32 (40%). In addition, aberrations of 19p13.3, 16p13.3, 13q33-q34, 9q13-31, and 7q were reported for the first time. The presence of a close correlation of 17p13 deletion with abnormalities of some other loci implies that 17p13 could play a crucial role in oncogenesis. Interestingly, microsatellite instability was rarely seen in our patients, in contrast to that observed in European HCC samples.