The History of DNA Fingerprinting

I.                    Tiselius, 1933

a.       Invented electrophoresis for separating proteins

II.                 Frederick Sanger, 1963

a.       Developed sequencing procedure for proteins

III.               P. H. O’Farrell, 1975

a.       Invented two-dimensional electrophoresis

IV.              E. M. Southern, 1975

a.       Published his procedure for testing the existence of specific pieces of DNA

V.                 Alfred J. Jeffreys, 1984

a.       Discovered the fundamental processes behind DNA fingerprinting

b.      Studied gene for myoglobin

c.       Found non-functional “minisatelites” – areas near gene which vary between individuals

d.      When these segments were isolated, enhanced, and radioactively labeled they could be used to distinguish individuals through gel electrophoresis.

e.       The original process could take up to six weeks, but by 1991 Jeffreys had improved the test so that it took as few as two days.

VI.              1985 – First paternity test

VII.            1988 – First criminal conviction based on DNA evidence

VIII.         1989 – First conviction overturned based on DNA evidence

a.       Gary Dotson served 10 years of his 25-50 year sentence

IX.              Kary Mullis, 1993

a.       Won the Nobel Prize for the development of PCR (polymerase chain reaction) procedure.

b.      Made isolation and analysis of DNA quicker and easier by reducing the amount of DNA needed from the organism.

c.       He originally conceived the idea in 1983.

X.                 1996 – First conviction based on mitochondrial DNA

XI.              1999 – First “cold hit” obtained from a DNA database

a.       Wallid Haggag is convicted of burglary

b.      He was not a suspect, but police matched blood found at the crime scene to Haggag’s blood which was on record in the state DNA database

Problems with DNA Fingerprinting

I.                    Costs – Time and Money

a.       Can be very expensive and time-consuming

b.      Less of a problem since Kary Mullis’s development of PCR

II.                 Chance

a.       There are no clear matches – only probabilities.

                                                               i.      The DNA fingerprinting process examines several pieces of DNA, not the whole sequence

I.        Though unlikely, two individuals could have the same DNA fragments while being genetically distinct

II.     Racial and ethnic groups are likely to have similar VTNR’s

III.               The Human Factor

a.       Comtamination

                                                               i.      DNA from a lab technician or a police officer can become mixed with DNA from a suspect

b.      The Jury

                                                               i.      DNA fingerprinting can be confusing to explain to a jury.

                                                             ii.      Any doubt about contamination can destroy the validity of DNA evidence

c.       Misuse

                                                               i.      Planting DNA evidence to frame a suspect

                                                             ii.      Concerns about racial profiling stemming from similarities in VTNR’s