Question

At a criminal trial, the prosecutor presents the genotypes for three microsatellite loci

from the FBI CODIS set. He reports the DNA sample from the crime scene and one from the

suspect both have the genotype

at these three FGA₁/FGA_{4 ,}TPOX₁ /TPOX_{3 ,} VWA₂/VWA₇ microsatellites. He also presents the allele frequencies for the general population to which the suspect belongs. What is the probability that the genotype of the DNA evidence would match

that of the suspect given that the person who committed the crime and the suspect are different

individuals?

Alleles	Frequency
FGA1	0.30
FGA4	0.26
TPOX1	0.32
TPOX3	0.65
VWA2	0.23
VWA7	0.50

Answer 1

The suspect's genotype has these three FGA1/FGA4 ,TPOX1 /TPOX3 , VWA2/VWA7 microsatellites.

Now, the probability that any individual from the population will have this genotype, is equal to the product to frequency of individual alleles.

Hence, required probability,

= (0.30) × (0.26) × (0.32) × (0.65) × (0.23) × (0.50)

= 0.001865

Ans : 0.0018 or 0.1865%