Activity of red cell esterase D in 50 cases of retinoblastoma patients and their family members.

Esterase D was qualitatively and quantitatively analyzed in the red blood cells from 50 retinoblastoma patients who had been followed-up at Juntendo University and their family. In only one case with deletion of chromosome No. 13 (q12.3-q21.2), was the esterase D activity (type 2) 1.47 Unit/gHb which was approximately 50% of the level in normals. Additional retinoblastoma patients and their family members, 77 parents and 25 siblings, showed a normal range of esterase D level in their own phenotypes. These facts confirmed that the deletion of an esterase D locus was infrequent (approximately 2% in our series) in retinoblastoma patients. It was also compatible with the published data that the range of deletion of chromosome was No. 13 (q12.3-q21.2) involving 13q14.