Loss of heterozygosity on chromosome 1 in human hepatoblastoma.

In previous studies we have found loss of heterozygosity (LOH) on chromosome arm 11p in 33% of hepatoblastomas (HBs). In addition, cytogenetic studies have revealed aberrations of chromosome arm 1p in single cases. Therefore, we have used the PCR to amplify 10 microsatellites on the short arm and 7 microsatellites on the long arm of chromosome I to assess allelic loss in 32 cases of HB. LOH on chromosome I was found in II cases. Seven HBs showed LOH on chromosome Ip, 7 cases had LOH on Iq, and 3 tumors had LOH on both Ip and Iq. Six HBs with LOH on Ip had LOH at DIS243 (Ip36.3), and one tumor had a loss at DIS80 maintaining heterozygosity at DIS243. A common region of overlap was present at the telomeric chromosomal portion of Ip between DIS80 and DIS243. Of the HBs with LOH on Iq, 4 showed a common region of overlap at Iq3I-q32.I, and the other 3 at DISI609 located more telomerically. The parental origin of the lost allele was of random distribution for chromosome arm Ip and of paternal origin for chromosome arm Iq. Our data suggest that tumor suppressor genes located at the telomeric region of chromosome arm Ip and different regions of chromosome arm Iq may be involved in the pathogenesis of HB.