12pter to 12p12.2: possible assignment of human triose phosphate isomerase

Red cell triose-phosphate isomerase (TPI) was determined, together with other enzymes, in three patients with chromosome 12 abnormalities. In patient No. 1 (trisomy of the segment 12 pter leads to 12q 12) and in patient No. 2 (trisomy of the segment 12pter leads to 12p 12.1), the TPI activity was significantly increased. In patient No. 3 (deletion of the segment 12 p 11 leads to 12 p 12.2), the TPI activity was in the normal range. These results suggest that the human TPI locus is located on the chromosome 12 short arm, between 12p ter and 12 p 12.2.