Autoradiographic Studies of Human Chromosomes

Summary. Cytogenetic analysis combined with blood grouping in a phenotypically abnormal child and his family suggest that the MN locus is in the long arm of either chromosome No. 2 or chromosome No. 4. The propositus, who is type M, appears to be hemizygous at the MN locus, or has a condition that cannot be distinguished from hemizygous by serological methods. The father, who is type N, is homozygous N/N by dosage estimations. The caryotype of the propositus is 46,XY,t(2q‐; 4q +). About one‐half of the distal part of the long arm of a No. 2 has been translocated to the distal end of the long arm of a No. 4.