Chromosomes of a Human Neuroblastoma: A New Case With Accessory Minute Chromosomes

The chromosomes in a human neuroblastoma were analyzed. The stemline karyotype included 46 chromosomes of normal size and, in most cells, a varying number of minute chromosomes. Most of the normal chromosomes conformed completely to the normal human karyotype, except for one member of pair #2, one extra chromosome in the C group, and one chromosome missing in the D group. The deviating chromosome #2 had a lengthier long arm than normal. The extra chromosome in the C group was one of the smallest chromosomes of this group. Since it deviated from the normal C chromosomes and was sometimes involved in satellite associations with a D group chromosome, it was thought to represent the missing D chromosome. Other D chromosomes also deviated somewhat in appearance, in that their short arms were too large. An idiogram of the tumor stemline was constructed from measurements of all chromosomes of 11 cells. The minute chromosomes were evidently centric. Their mitotic behavior, however, was irregular, as evidenced by their wide variation in number between cells (0–58 per cell, average 7.9). Certain similarities between these minutes and accessory chromosomes (B chromosomes) of natural organisms are pointed out.