Fibroblasts from retinoblastoma patients: enhanced growth in fetal calf serum and a normal response to ionizing radiation.

Retinoblastoma is a rare malignant eye tumor found almost exclusively in young children. In 30% of cases, the tumor is bilateral and is inherited as an autosomal dominant trait. In such patients, all of the cells in the body must carry the mutation predisposing to retinoblastoma. To search for the expression of the gene in cells outside the retina, we have studied several in vitro properties of skin fibroblasts from patients with bilateral retinoblastoma. Measurement in low concentrations of fetal calf serum of the initial growth rate and the plating efficiency show that fibroblasts from retinoblastoma donors grow significantly better than those from normal donors. However, we were unable to confirm the results of other investigators that fibroblasts from donors with bilateral retinoblastoma are unusually sensitive to ionizing radiation. In family studies, skin fibroblasts from normal siblings had the same radiation sensitivity as fibroblasts from siblings with retinoblastoma.