Brief Report: Chromosome-21 and Paroxysmal Nocturnal Hemoglobinuria

A LTHOUGH great strides have been made in the past decade in both cytogenetics and biochemical genetics, the location of genes on the 44 autosomes has remained unknown. The experiments of nature in which an additional chromosome-21 is present and where a portion of this chromosome has been deleted have provided, for the first time, a clue to the possible location of some autosomal genes. The studies of Alter and his associates 1 , 2 were the first of a series of investigations suggesting that a gene regulating the formation of leukocyte alkaline phosphatase was located on this chromosome. 3 , 4 , 5 , 6 , 7 A flurry of reports has followed suggesting that genetic control of ABO blood group substances, 8 galactose-1-phosphate uridyl transferase 9 but not the D antigen 10 may also be located on this chromosome.