RT-PCR on RNA from different liver sections and fibroblasts. Total RNA was extracted from various samples, reverse transcribed and amplified by PCR. The 537-bp fragment starts in the middle of exon 6 and ends in the middle of exon 12. A- RT-PCR products amplified from total RNA extracted from different liver regions i.e. non-tumoral (lane 2) and tumoral (lane 3) and from fibroblasts of the patient (lane 4). (lane 1: Control RNA from T19-EBV normal cells). B- RT-PCR products amplified from total RNA extracted from transformed lymphocytes of the parents (father; lane 1, mother; lane 2) and cultured fibroblasts of another patient homozygous for IVS6-1g->t (lane 3). A normal length cDNA is seen in the reverted nodule (537-bp, A, lane 2) and in both parents. Three of the products seen in the tumor liver section (A' lane 3) are also observed in a patient homozygous for the IVS6-1g->t mutation (B, lane 3).