ALLELIC LOSS OF THE RETINOBLASTOMA TUMOR-SUPPRESSOR GENE - A MARKER FOR AGGRESSIVE PARATHYROID TUMORS

Allelic loss of the retinoblastoma tumor suppressor gene has recently been shown to be highly specific for parathyroid carcinoma. It has bee n proposed that this genetic abnormality may have diagnostic and progn ostic implications for parathyroid carcinoma, but to date no further s tudies are available to substantiate these findings. In the present st udy, three cases of atypical recurrent hyperparathyroidism were examin ed: a patient with parathyroid carcinoma and an autotransplanted adeno ma that progressed into carcinoma, a patient with recurrent juvenile h yperparathyroidism, and a patient with severe recurrent secondary hype rparathyroid disease due to rapidly growing autotransplant. Six pairs each of sporadic parathyroid adenoma and secondary parathyroid disease were also studied for comparison. Allelic losses of RB and D13S71 at 13q14 was found in the parathyroid carcinoma and the corresponding aut otransplant that had previously been considered benign tissue and in t he case of recurrent juvenile hyperparathyroidism, but not in any of t he other tumors. Our findings support the findings of the previous stu dy that RB or 13q loss is specific for parathyroid tumors with increas ed aggressiveness and might be of clinical significance.