153 
1 systems. 
2 Until the advent of recombinant DNA technology, 
3 the somatic cell genetic technique could only analyze 
4 the human genetic material at a relatively low level of 
5 resolution. Making use of recombinant DNA procedures, 
6 it is now possible to continue the study of human genetics 
7 at a very high level of resolution. It is like comparing 
8 the light microscope to the electron microscope. 
9 Using nucleic acid hybridization techniques, 
10 our laboratory in collaboration with an NIH research group, 
11 has recently mapped the human genes for alpha and beta 
12 globins. This knowledge now provides new possibilities 
13 for experiments dealing with a better understanding of 
14 the control of hemoglobin expression with obvious rele- 
15 vance to genetic, developmental, and environmentally 
16 induced abnormalities involving human hemoglobins. We 
17 are now beginning to use cloned -- that is, recombinant -- 
18 cloned material -- globin DNA sequences -- for this purpose, 
19 a method which is far simpler, faster, more reliable, and 
20 cheaper than those previously employed. 
21 It should also be strongly emphasized that 
22 many biologically important human genes will be mapped 
23 in man only — and I would like to emphasize "only" -- by 
24 using recombinant DNA technology in concert with the 
25 somatic cell genetic procedure. There have been statements 
[ 245 ] 
