October 2000 - Volume 2 - Number 4

Interpreting DNA Mixtures Based on the
NRC-II Recommendation 4.1

Table 1
All Possible Genotypes of
Two Unknown Persons and Their Corresponding Probabilities in Computing p₂ +cd * abcd ,

Case	Genotypes of 2 unknowns	Probabilities
1	aacd	4( pa Ú pa )( pc Ú pd ) + 8( pa Ú pc )( pa Ú pd )
2	bbcd	4( pb Ú pb )( pc Ú pd ) + 8( pb Ú pc )( pb Ú pd )
3	accd	4( pc Ú pc )( pa Ú pd ) + 8( pa Ú pc )( pc Ú pd )
4	acdd	4( pd Ú pd )( pa Ú pd ) + 8( pa Ú pd )( pc Ú pd )
5	bccd	4( pc Ú pc )( pb Ú pd ) + 8( pb Ú pc )( pc Ú pd )
6	bcdd	4( pd Ú pd )( pb Ú pc ) + 8( pb Ú pd )( pc Ú pd )
7	ccdd	2( pc Ú pc )( pd Ú pd ) + 4( pc Ú pd )2
8	cccd	4( pc Ú pc )( pc Ú pd )
9	cddd	4( pd Ú pd )( pc Ú pd )
10	abcd	24( pa Ú pb )( pc Ú pd )

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Table 2
A Rape Case in Hong Kong

Loci	Evidence profile (E) and frequencies (F)	Victim (V) and suspect (S) profiles
D3S1358	E = {14, 15, 17, 18}	V = {15, 18}
	F = {0.033, 0.331, 0.239, 0.056}	S = {14, 17}
vWA	E = {16, 18}	V = {18, 18}
	F = {0.155, 0.158}	S = {16, 16}
FGA	E = {20, 24, 25}	V = {20, 24}
	F = {0.042, 0.166, 0.106}	S = {25, 25}

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Table 3
Likelihood Ratios for the Case in Hong Kong
With Two Sets of Hypotheses

Hypothesis	q	D3S1358	vWA	FGA	Combined
S1	0	63.4	13.7	18.1	15,721
	0.01	63.4	13.5	17.8	15,235
	0.03	63.4	13.0	17.2	14,176
S2	0	285.4	119.0	359.2	12,175,485
	0.01	285.4	114.0	349.2	11,339,010
	0.03	285.4	104.0	331.2	9,810,840

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Table 4
The Likelihood Ratios for the Simpson Case
With a Three-Allele VNTR Mixed Profile

n*	qor 2p	m*
		0	1	2
2	q = 0	1,623	70	3.06
	q = 0.01	1,554	70	3.19
	q = 0.03	1,431	70	3.46
	2p	158	70	31.06
3	q = 0	21,606	938	41.06
	q = 0.01	19,427	881	40.06
	q = 0.03	15,914	783	38.06
	2p	54	24	11.06
4	q = 0	396,495	17,220	748.06
	q = 0.01	338,541	15,352	696.06
	q = 0.03	251,636	12,373	609.06
	2p	68	30	13.06
*The number of unknowns in Hd and Hp are n and m, respectively.

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