On the application of bloodtests to legal cases of disputed paternity

Revue de Transfusion, T, XII. N ° 1.

-

-

1969

137

On the application of bloodtests to legal cases of disputed paternity by K. H E N N I N G S E N , M.D. The Serologic Department University Institute of Forensic Medicine, Copenhagen

HE use of bloodgroups as a means of investigating disputed paternity was introduced in D e n m a r k about ]925 and since 1927 all forensic bloodgrouping in D e n m a r k is centralized at the University Institute of forensic Medicine, Copenhagen.

T

2400

~otal : 6 1 4 9 9

2200 2000 ~800 1600 1400 1~00

1000 8OO 6OO ¢oQ' 2o0 19~ Fla.

1.

193o --

19~53

L 19~o

,t 1945

J 195o

x9551 , -

1 9t6 o

t 1965

I1967

Y e a r l y n u m b e r o f paternity cases e x a m i n e d by the Institute since

1927.

+otK~ HENNINGSEN

138

The increasing number of bloodgroup determinations in cases o.f disputed paternity is seen from figure 1. Since the war this curve reflects the general birthrate in the Danish community. Each year about 10 per .cent of newborn children are born out of wedlock and of these approximately 1 / 4 or about 2 000 per year, leads to a legal case of disputed paternity. However the curve shows only part o'f the story. The informative yield of bloodtests has also increased very substantially as, seen from figure 2 in w h i c h it is expressed by the theoretical percefitgge 0,f exclusion. Theoretical perhentage o£ exclusion STANDARD

ioo

EXTENDED

ANTHROPOLOGICAL

-/

88 PERCENT

9o 80 PERCENT 8o 7o

?/ t

6o 5o 40

-

I 3o

I l

2o

I I

io

I

I

biN

I

I~h

Hp

Systems

in

use

A I A BO

I I

i

F

I

I

K Seer.

P

Fya

Ss

G¢

I

I Gm Jka

I

I

I Kpa

i PGM AK

t AP

FIG. 2. - - The present (1968) yield of the blood examination at the University Institute o f F o r e n s i c M e d i c i n e s C o p e n h a g e n , as expressed by the theoretical percentage of exclusion.

From the h u m b l e 16 per cent of the ABO-system the percentage has to day risen to between 80-90 per cent. Of course the curve is levelling out due to s i m u h a n e o u s exclusions in different systems and the addition to the general percentage from n e w systems is only a fraction of their informative value. However, the diminishing yield 'with regard to exclusions, w h e n more and more sys'tems are put to use, is to some degree counteracted by a growing number of type constellations telling positively for paternity. The importance of sufficient k n o w l e d g e o'f the genetics w h i c h form

BLOODTESTS TO LEGAL CASES

139

the biological basis o:f the use of bloodgroups in paternity cases is well known, but the importance of the legal background is less appreciated. In D e n m a r k the legal status of children born out of wedlo¢k since 1937 has been the same as the status o'f legitimate children, also with regard to name and heritage fro.m the father, provided paternity was accepted by the man or conferred to h i m by a decision of the court. However, in many cases the court did not reach a decision of paternity but was content to sentence the man to pay alimony to the child. Since 1961 a new bill on the legal status of children has come into operation. Concerning illegitimate children this bill introduces directly the conception of probability ~rf paternity by stating, that a man who has had intercourse with the m o t h e r of a child at the period of conception, shall be pronourreed the legal father, unless his paternity f~or some reason - - as for instance the bloodtest - - is little probable. If two or more men are involved in the cases, the condition for pronouncing one of the men as father is that his paternity is f o u n d to be essentially more probable than that of any other man. If, according to the court's decision, one of the men is adjudicated paternity, the other men in the case are acquitted, t f no man are ,found more probable than the other men, all the men are acquitted, and in most of these cases the woman may draw alimony for her child from the state. This concept of probability means among other things that any biological evidence is admissible in court. F u r t h e r that the court is anxious to obtain as much biological information as possible, for instance also bloodgroup statistical comparisons. Finally it requires a more comprehensive and detailed explanation o'f biological and statistical problems from the biologist to the court. F o r m e r l y only two possibilities existed. Either the putative father was <>with sufficient certainty to be acquitted regardless of other circumstances of the case, or he was not excluded, in which case the hloodgroup examination did not yield any other pertinent information. The finding o~f exceptions to the accepted rules o,f heredity even i n the << old >> accepted systems and the introduction of <> systems involving greate~ risks of exceptions have in many instances limited the use of blood groups within the old bill's framework of all or nothing. The stipulations o'f the present law have changed this and to day we have to ~valuate i] and to w h a t e x t e n t the bloodgroup result tells ]or or against paternity. I n D e n m a r k the m o t h e r of a child born out of wedlock is obliged by law to disclose the name of the father to the authorities. If the man

140

K. H E N N I N G S E N

refuses to accept p a t e r n i t y , the law ,further s t i p u l a t e s t h a t legal action has to be t a k e n i n o r d e r to d e t e r m i n e t h e p a t e r n i t y . I f t h e m o t h e r of t h e c h i l d has h a d m o r e t h a n one sexual c o n t a c t at the p e r i o d of c o n c e p t i o n , she is also o b l i g e d b y l a w to n a m e all those contacts, a n d t h e n all of t h e m are b r o u g t i n t o t h e e n s u i n g p a t e r n i t y case. I n our i n s t i t u t e ' s m a t e r i a l the p r o p o r t i o n of o n e - m a n cases a n d m o r e - m e n cases has b e e n very stable ~for m a n y years. A c c o r d i n g to t h e 'first exp l a n a t i o n of the m o t h e r 2 / 3 of t h e cases i n v o t v e o n l y o n e m a n , w h e r e a s she is a d m i t t i n g to i n t e r c o u r s e w i t h two or m o r e m e n i n 1/3 of t h e cases. T h e p e r c e n t a g e of n o n - f a t h e r s i n o n e - m a n cases 'may be c a l c u l a t e d f r o m the r e l a t i o n b e t w e e n a c t u a l a n d theoretica'l percentage o~f exclusion. T h i s is also very stable a n d has ,for m a n y years s h o w n 20 p e r c e n t to be n o n - f a t h e r s . F o r several p r a c t i c a l reasons we h a v e to l i m i t the use of some of the systems to cases i n v o l v i n g two or m o r e m e n . T h e f o l l o w i n g slide shows t h e e x t e n t of o u r s t a n d a r d e x a m i n a t i o n for o n e - m a n cases a n d o u r e x t e n d e d e x a m i n a t i o n as used i n m o r e - m e n cases. TABLEAU I.

THEORETICAL PERCENTAGE OF EXCLUSION EXTENT

USED FOR I

DISCRETE

COMBINED

i

Standard Examination

AIA2BO M,N Rh Hp K

Extended Examination

Secretor P Fya Ss(MN) Gc Gm

Maximal Examination

18 I

19 29 18

10 15 25

Jka

3

Kpa AK PGM AP

13 22

63 per cent

I

All cases

47 More men cases not solved per c e n t by the standard examination

37

per cent

Selected cases for socalled anthropological examination.

BLOODTESTS TO LEGAL CASES

141

I t is e v i d e n t t h a t i n the o n e - m a n cases w h i c h Mter the s t a n d a r d i n v e s t i g a t i o n i n c l u d e less t h a n 8 p e r cent n o n , f a t h e r s , the r e t u r n of a p p l y i n g t h e m o r e e x p e n s i v e a n d t i m e c o n s u m i n g i n v e s t i g a t i o n s is slight, a n d at p r e s e n t we p r e f e r to reserve such i n v e s t i g a t i o n s for cases all of w h i c h i n c l u d e n o n , f a t h e r s i.e. the m o r e - m e n cases. Of course the i n s t i t u t e p e r f o r m s the e x t e n d e d e x a m i n a t i o n also i n o n e - m a n eases, if the c o u r t for some reason af o t h e r n e e d s this f u r t h e r i n f o r m a tion. T h e folJowing case is a n e x a m p l e of the << exclusion >> of one m a n together w i t h positive e v i d e n c e o n the p a t e r n i t y of the o t h e r m a n .

TABLEAU II

Mother

A1MNS-- C + C W - - D + E + c + P + K - - F y a + Hp 2--1 Gc 1--1 Gm(a+x b + )

Child

A1NS-- C-4-CW--D@E--c+P+~(--Fya+ Hp 1--1 Gc 2--1 G m ( a + x + b + )

1. man

ONS--- C + C W - - D + E - - c + P - F K - - F y a + Hp 2--1 Gc 2--1 Gm(a+x--b-F)

2. man

A1BMNS+ C - - D - - E - - c + P ~ K - - F y a - - Hp 2--'1 Gc 2--1 Gm(a+x+b--)

The paternity of the second man is excluded according to the results of the Gm-system with a reliability estimated to be between 99 and 99,9 per cent. By a blood group statistical evaluation the blood group statistical paternity index of the first man is found to be 37,5 and according to the assessment of the Institute substantially points towards his paternity. T h e statistical e v a l u a t i o n is p e r f o r m e d b y m e a n s of a << b l o o d group p a t e r n i t y i n d e x >> c a l c u l a t e d i n t h e f o l l o w i n g way. Based o n the laws of h e r e d i t y a n d the gene f r e q u e n c i e s i n o u r m a t e r i a l the frequency of a n y m o t h e r , f a t h e r - c h i l d c o m b i n a t i o n w i t h i n the different systems has b e e n c a l c u l a t e d a n d r e l a t e d to the .frequency o'f said mot h e r - c h i l d , m a n f r e q u e n c y i n the p o p u l a t i o n or i n o t h e r words the frequency of said c o m b i n a t i o n s i n a m a t e r i a l of t r u e fathers relative to the ' f r e q u e n c y i n a m a t e r i a l of nonJfathers. This p r o p o r t i o n will, if greater t h a n 1 tell for, if less t h a n 1 tell against p a t e r n i t y . T h e indices of the d i f f e r e n t systems are c o m b i n e d to a c o m m o n i n d e x w h i c h expresses t h e t o t a l i n f o r m a t i o n of the b l o o d g r o u p e x a m i n a t i o n . I n our e x p l a n a t i o n to the c o u r t we h a v e a r b i t r a r i l y c h o s e n a 95 per cent l i m i t

142

K. HENNINGSEN TABLEAU III

Mother

BMS~ Cq-CW Dd-E--c--P-4-K--Fya-- Hp 1--1 Gc 1--1 Gm(a--x--bd~)

Child

BMNS~ Cd-CW--Dd-E--c--Pd-K--Fya-- Yfp 2--1 Gc 1--1 Gm(a--x--bd-)

1. man

ONS--Cq-CW--Dd-E~c--Pd-K~Fya-- Up 2--2 Gc 1--1 Gm(a--x--bd-)

2. man

OMNS-- C+CW~Dd-E--cd-Pd-K--Fya -4- HD 2--1 Gc 2--1 Gm(ad-x--bd-)

Blood group statistical evaluation The blood group statistical paternity index for the men examined in the present case is found to be the following : 1. m a n : 50.35 2. man : 0.58 The relation of the indices of the two men are l. man 50.35 87 99 = - - - - or - - or expressed in per Cent - 2. man 0.58 1 1 Thus according to the Institute's assessment the blood group statistical evaluation sub~tahtially points towards the paternity of the first man.

o,f s i g n i f i c a n c e i.e. the i n d e x m u s t b e > dered significant.

20 a n d <

0.05 to b e Consi-

I n t h e n e x t case n e i t h e r of t h e two m e n are ex,c l u d e d b u t b y a c o m p a r i s o n of t h e i r << b l o o d g r o u p p a t e r n i t y i n d i c e s >> t h e b l o o d g r o u p c o n s t e l l a t i o n i s 'found to tell Jor n u m b e r Fs p a t e r n i t y c o m p a r e d to n u m b e r 2's p a t e r n i t y w i t h a w e i g h t of 99 p e r cent. ,It is e v i d e n t t h a t o n e o'f t h e p r e r e q u i s i t e s for such c a l c u l a t i o n s - a n d for t h e r e l i a b i l i t y of e x c l u s i o n s w h i c h is e s t i m a t e d a c c o r d i n g to s i m i l a r p r i n c i p l e s - - is k n o w l e d g e of r e p r e s e n t a t i v e g e n e f r e q u e n c i e s a n d a h o m o g e n e o u s p o p u l a t i o n . T h e q u e s t i o n o,f r e l i a b i l i t y o,f exclu. sions is of course m o s t i m p o r t a n t a n d has n f h n y aspects as for insfanee p r o b l e m s o~f i d e n t i t y of b l o o d s a m p l e s , risks of s i m p l e l a b o r a t o r y a n d clerical errors, risiks of e r r o n e o u s e x c l u s i o n s due to u n s u s p e c t e d variations of test sera ~f a p p a r e n t l y i d e n t i c a l speci,ficity :etc. I t r u s t t h a t we are all t h o r o u g h l y f a m i l i a r w i t h t h e m e t h o d s b y w h i c h such prob l e m s are c o m b a t e d , n e v e r t h e l e s s I w a n t to stress~the i m p o r t a n c e of t e s t i n g all p a r t i e s i n a n e x c l u s i o n case w i t h t h e s~me test s e r u m and p r e f e r a b l y w i t h several sera of s u p p o s e d l y id¢r~ical specificity. Not to do this m a y lead to grave e r r o r s i n :some 'of t h e :more c o m p l i c a t e d systems.

BLOODTESTS TO LEGAL CASES

143

Another and more ex~citing aspect of the reliability is the problem ~f the consistency of the applied genetic rules in the population in question,. As it is known, for instance from Dr METAXAS investigations on the Mg~ problem, 'factors which in some populations are very rare may have surprisingly high frequencies in another population. A.ccording to oatrl material the high Mg frequency of S'witzerland, which with ordinary anti~M sera may lead to ,false exclusions, is not found in Denmark, as may be deduced ,from the fact that in our mother/ child material, numbering more than 60.000 mother/child pairs, only 2

,¢ •

FIG;

3

K. HENNINGSEN

144

proven << exceptions >> to the heredity of the M~-~factors have been encountered, neither of w h i c h were due to Mg. The genetic reliability of exclusions must in principle be cMculated from materials originating from the population in question. It is in this respect important to c h e c k the h o m o g e n e i t y of the population. In a survey of the gene~frequencies o,f the A.BO- and Rhsystems in Denmark, only small differences were found between the various parts of the country and no isolates with significantly deviating frequencies were demonstrated. For instance the following slide shows that the rare R h - c h r o m o s o m e s were f o u n d rather evenly distributed all over the country. Nonetheless we have in our .material ef paternity cases indications that at least one ef the rare Rh-genes w h i c h m a y giwe rise to false exclusions m a y be accumulated in a very special part of Denmaflk, the small atlantic islands, the Faroe Islands. In 1955 and 1957 we found apparent m o t h e r / c h i l d e~clusions in two paternity cases from the Faroe Islands. The two w o m e n proved to be sisters and to come from a large family in a small village. By family investigation the c h r o m o s o m e D - - w a s demonstrated as shown on the slide.

"DELETED"

Rh-CHROMOSOMES

IN

LEGAL

PATERNITY

CASES

• Chromosom~ O-- in ?. separate paLernity cases wlthin t family from +he Foroe i s ! a n d s . L~')64" c-E--

C-¢+ E+

U+

D+

D+

D+

O+

D+

O.

C+

C+

C

C--

C--

C+

C+

C--

C--

C+

C"

C+

c+

¢+

c

c4-

c+

c+

c+

c+

C+

E+ ~*+

E-~+

E+

E+

E-

E,

e--

e+

e+

e

E-e

E+

£

E--

oc

,:

D+

E

E+

E+

t

e+

e--

o.~

•

o=%..

~

D+

O+

%..,,o,

D+

+

=

%.

~c,,,ocO,:~ oc,~, o

D+

D+

D+

D+

D+

D+

D+

D'F

D+

D+

D+

D+

D+

D+

C+ c÷

C'lc+

C-e+

C+ c+

C-c+

C+ c -

C+ c+

C+ c "1"

C-c+

C-c+

C+ c+

C+ c+

C+ e--

C+

Ee+

E+ e+

E+ e+

E--E+ e+ *--

:-" +

E; e

E; e

E-e÷

E; e

E-e+

E-e+

E-o+

DC~tOCe/OcEO=% OC~.oOce/Oct

~:~OC¢/dctOC~© + d+,¢~, d,~tt:,.. O¢%c OC%=.

DC%..

•

cE-¢+

PC%..

$ • 'delded" R h - c h r o m o s o m e . Q n o ~ e x o r n l n e A.

s~, p o ~ e r n i t y case B/4./55. ~ pcr['ern;'ty case B 315/$7.

OI put¢t'iive ft~ther.

FIG. 4

145

BLOODTESTS TO LEGAL CASES

In 1964 we h a d another case of m o t h e r / c h i l d Rh-exclusion in the Faroe Islands. T h e m o t h e r in the last case lived in the principal town Thorshavn, b u t came f r o m a small village quite a p a r t f r o m the village of the first family and any relation-ship with this family was denied. From the slide the locMisation of the two villages is seen. However, later it was ,found that the two families nonetheless were related. 100-150 years ago a very poor m a r r i e d couple in Thorshavn had to send their 2 sons away. One was sent tO the first of << our >>villages the other to the second and the 3 w o m e n in our paternity cases having the D-- gene were direct descendants of the brothers, a h h r o u g h the relationship had been completely forgotten in the intervening more than 100 years.

p

[]

--Q

/'~ []

Q

1

1

1

•

~

[] Q

2)-:,or~x~..,:,,'~.

FIG. 5

In view of the relatively small and isolated population on the Faroe Islands the case serves to illastrate the risk of having completely deviating gene-frequencies in small geograf~cally, or for that matter socially, isolated communities, and it is evident that such deviations, if unsuspected, m a y lead to false conclusions. 10

145

K. HENNINGSEN

W i t h t h e d i s c o v e r y of t h e h e r e d i t a r y s e r u m systems H p , Gc, Gin, etc. a m o s t i m p o r t a n t step f o r w a r d was t a k e n , a n d n o w n e w series of p o l y m o r p h i s m s , t h e e n z y m e s of t h e e r y t h r o c y t e s a r e a p p e a r i n g .

1963 HOPKINSON, ,SPENCER a n d HARRIS d e m o n s t r a t e d a g e n e t i c pol y m o r p h i s m of t h e r e d c e l l e n z y m e s A c i d P h o s p h a t a s e ( A P ) a n d l a t e r Phosphoglucomutase (PGM) and Adenylattekinase (AK). In our lab we h a v e b e g u n to i n v e s t i g a t e t h e s e s y s t e m s a n d I w i l l c o n c l u d e this p a p e r b y s h o w i n g o u r p r e l i m i n a r y results. As y o u kno~w t h e m e t h o d of d e t e r m i n a t i o n is a n ele~ctrophoretic s e p a r a t i o n of t h e e n z y m e fractions on s t a r c h gel w i t h s u b s e q u e n t d e m o n s t r a t i o n of d i f f e r e n t p a t t e r n of zones o f e n z y m a t i c a c t i v i t y . Fig. 6 shows t h e S P d e t e r m i n a t i o n w i t h s o m e of t h e m o r e freq u e n t types. T h e ~phenotype a n d gene f r e q u e n c i e s , t h e theoretircal a n d a c t u a l p e r c e n t a g e of e x c l u s i o n i n 67 (56) p a t e r n i t y cases a n d t h e m o t h e r / c h i l d a n a l y s i s a r e g i v e n i n t a b l e a u IV. I n 11 o u t of t h e 67 cases the s a m p l e of o n e or a n o t h e r of t h e p a r t i e s (as a r u l e t h e c h i l d ' s ) was unsat i s f a c t o r y a n d d i d n o t a l l o w a r e l i a b l e diagnosis. TAREF~U IV Analysis of Material of Acid Phosphatases NON

TYPE

A AB B

BC AC C ? Total

.'NTO. OBS.

NO. EXP.

22 80 65 7 4 1 6

22.14 75.07 63.63 7.62 4.50 0.23 11.61

185

184.80

RELATED ADULTS

X2

0.0009 0.3238 0.0294 0.0510 0.0159 0.42

REL. FREQ.

11.9 43.2 35.1 3.8 2.2 0.5 3.2 99.9 per

cent

GENE FREQUENCIES

AP a AP AP ° AP?

0.3459 0.5865 0.0351 0.0324

Theoretical percentage of exclusion : 22 per cent Number of cases examined : 67 (56) Number of paternity exclusions : 7

BLOODTESTS TO LEGAL CASES

147

F:G. 6

K. HENNINGSEN

148 ~WOTHER-CHILD ~V~ATERIAL CHILDREN

Mothers

A OBS. EXP.

AB

B

OBS. EXP.

OBS. EXP.

4 4

2.79 4.73

AC BC C

0 0 0

.28 0 0

5 4.73 12 12.74 6 8.01 1 0.48 0 0.48 0 0

Total

8

7.80

24126.44 ] 24 22.41

A AB B

0

0

9 15 1~.59 0 0 .81 0

AC

OBS. EXP.

1 0 0 ~

BC

OBS. EXP.

C

OBS. EXP.

Total

0

0

0

0.28 0.48 0 0.31 0.48 0.03

0 0 1 3 0

0.48 0.81 0.48 0.86 0.05

0 0 0 0

10 25 21 0 2 0.03 3 0.05 0.003 0

1

1.581

4

2.68

0

0.083

0

61

x) The expected values for the mother-child table are calculated from approximative gene frequencies disregarding the n u m b e r of dubious results in the adult material.

T h e ~follo'wing f i g u r e s s h o w t h e

same

analysis for the PGM

and

AK systems. I t is s e e n t h a t t h e r e s u l t s s e e m t o b e c o n s i s t e n t a n d v e r y p r o m i s i n g but

I want

to stress, that

this

presentation

is p r e l i m i n a r y

these systems are only used in special cases in which called anthropological additional

information

examination

is p e r f o r m e d ,

in some of the

and that

t h e I n s t i t u t e ' s so-

a n d a t t h a t , o n l y as

cases. M u c h

work

h a s s t i l l to

TABLEAU V

Analysis of Material of Phosphoglucomutases.

NON RELATED ADULTS : REL. FREQ.

TYPE

No. OBS.

NO. EXP.

X2

1~1

121

120

0.008

65.4

2--1

56

58

0.068

30.3

2--2

8

7

0.141

4.3

185

185

0.217

Total

GENE FREQUENCIES

100

PGM x 0.805 PGM 2 0.195 Theoretical percentage of exclusion : 13 per cent Number of cases examined : 67. Number of paternity exclusions : 9

BLOODTESTS TO LEGAL CASES

149

Fro. 7

K. HENNINGSEN

150 MOTHER-CHILD MATERIAL CHILDREN

Mothers

1--1

2--1

OBS. EXP.

OBS. EXP.

1--1 34 35.5 2--1 7 8.6 2--2 0 0 Total 41 44.1

9 8.5 9 10.7 4 2.1 22 21.3

2--2

OBS. EXP

0 4 1 5

0 2.1 O.5 2.6

TOTAL

43 20 5 68

b e d o n e w i t h r e g a r d to r e p r o d u c i b i l i t y , c a l c u l a t i o n of r e p r e n s e n t a t i v e genefrequencies,

i n v e s t i g a t i o n s on r e l a t i o n s h i p to t h e o t h e r systems

used, c o m p i l a t i o n s o f m o t h e r / c h i l d m a t e r i a l s etc. b e f o r e t h ese systems may come into their own

alongside other

a c c e p t e d systems in o u r

forensic blood group armoury. The

forensic biologist must

have sufficient m a t e r i a l

a n d e~pe-

r i e n c e to e s t i m a t e t h e r e l i a b i l i t y a n d w e i g h t of t h e e v i d e n c e h e presents to t h e court. I t is his o b l i g a t i o n to p r e s e n t t h e e v i d e n c e in such

TABLEAUVII

Analysis of Material of Adenylate Kinases.

~ON RELATED ADULTS

TYPE

No.

OBS. No.

EXP.

X2

FREQ.

1--1

176

176.1

0.00007

95.1

2---~1 2--2

9 0

8.8 0.1

0.00137

4.9 0

Total

185

185

0.0014

100.0

GENE FREQUENCIES

AK 1 0.9757 A ~ 2 0.0243 Theoretical percentage of exclusion : 2.3 per cent Number of cases examined : 67 Number of paternity exclusions : 0.

BLOODTESTS TO LEGAL CASES

151

FIG. 8

152

K. H E N N I N G S E N ~/[OTHERs-CHILD MATERIAL CHILDREN 1--1 OBS. EXP.

Mothers

2ml OBS. EXP.

1--1 64 64.0'86 2--1 2 1.598 2--2 0 0

0 2 0

Total 66 65.684

2 3.275

1.598 1.638 0.039

2--2 OBS. EXP.

TOTAL

0 0 1 0.039 0 0.001

64 5 0

1 0.040

69

a way that the court is able to assess the pertinence of the evidence, but it is the liability of the court to decide i~f the professed biologic evidence is reliable and weighty enough to be applicable to the wording and sense of the law. K. HENNINGSEN

University Institute of Forensic Medicine Frederik 5 vej, 9 Copenhague Danemark

RESUME A u Danema~k, depuis 1927, t o u s l e s cas de recherche de paternit6 sont centralis6s h l'Institut Universitaire de M6decine L6gale, h Copenhague. Leur n o m b r e d6passe 2.000 par an. Les examens standards, faits pour t o u s l e s ~as, portent sur les syst~mes A1A2, MN, Rh, Hp et K. Si aucune 'exclusion n'est observ6e, et surtout qnand il y a plusieurs hommes en cause, d'autres syst~mes sont mis en oeuvre : s6cr6tion ABH, P, Fy (a), Ss', Gc et Gin. En incluant ces derniers, la probabilit6 a priori d'exclusion atteint 80 p. 100. Dans des ~cas sp6ciaux, on &udie Jk (a), K p (a), la phosphoglucomutase, l'ad6nylate kinase et la phosphatase acide, amenant cette probabilit6 h 88 p. 100. Selon les dispositions 16gales, les experts doivent dire si les r6sultats obtenus sont << pour >>ou <>la paternit6, et dans quelle

BLOODTESTS TO LEGAL CASES

153

mesure. L ' a u t e u r u t i l i s e p o u r cela u n << i n d i c e de p a t e r n i t 6 >~ calcul$ p o u r c h a q u e syst~me. Les i n d i c e s o b t e n u s p o u r les diff6rents systgrues s o n t combin6s. Le n o m b r e ainsi o b t e n u p e r m e t d ' e s t i m e r , au cas off il n ' y a pas d ' e x c l u s i o n p r o p r e m e n t dire, si les r~sultats p e u v e n t gtre i n t e r p r 6 t 6 s en f a v e u r de la paternit.~, ou sont un a r g u m e n t c o n t r e die. Les r i s q u e s d ' e r r e u r , dans ces e x p e r t i s e s , sont b i e n connus : erreurs d ' i d e n t i t 6 , de l a b o r a t o i r e s , v a r i a t i o n s des s@ums-tests, etc... Certaines p e u v e n t ~tre dues h u n e f r 6 q u e n c e r e l a t i v e m e n t g r a n d e d a n s certaines p o p u l a t i o n s , de g6nes consid~rSs h a b i t u e l l e m e n t c o m m e tr~s rares. A i n s i , d u f a i t de sa r e l a t i v e m e n t g r a n d e f r S q u e n c e dans certaines p a r t i e s de l a Suisse, M g p o u r r a i t c o n d u i r e ~ d e ~fausses exclusions si les e x a m e n s 6 t a l e n t fairs s e u l e m e n t avec l es s~rums anti-M ordinaires. D ' u n e fa~on g6n~rale, il est i m p o r t a n t , p o u r e s t i m e r la fiabi~lit~ des exclusions, de s ' a s s u r e r de l ' h o m o g S n 6 i t ~ de la p o p u l a t i o n . Les gbnes )kBO et R h p a r a i s s e n t assez u n i f o r m 6 m e n t d i s t r i b u 6 s a u Danem a r k . N S a n m o i n s , il s e m b l e que te c h r o m o s o m e D - - soit f r 6 q u e n t dans les Iles F a r o ~ , off l ' a u t e u r a o b s e r v 6 des cas d ' e x c l u s i o n a p p a r e n t e de m a t e r n i t 6 d u e ~ ce c h r o m o s o m e . L a p o p u l a t i o n d e ces Iles forme u n i s o l a t p e u n o m b r e u x . L ' a u t e u r t e r m i n e en s o u l i g n a n t l ' i n t S r ~ t des syst~mes 6 r y t h r o e y taires r~v616s p a r u n e r S a c t i o n e n z y m a t i q u e : p h o s p h a t a s e acide, phosp h o g l u c o m u t a s e et a d S n y l a t e k i n a s e . P o u r le m o m e n t , ces syst~mes o n t besoin d ' g t r e 6tudi~s p l u s c o m p l ~ t e m e n t en r u e de l e u r a p p l i c a t i o n aux r e c h e r c h e s de p a t e r n i t 6 . M a i s ils r e p r 6 s e n t e n t un a v e n i r trgs p r o m e t t e u r et s o n t d6jh u t i l i s a b l e s d a n s c e r t a i n s cas p a r t i c u l i e r s .

REFERENCES HOPKINSON D.A., SPENCER N. and HARRtS H. : Red cell acid phosphatase variants : a new human polymorphism. Nature 199, 969 (1963). GiiRTLER I-I. : The Blood Group Distribution in the Danish Population and its

Application to Cases of Disputed Paternity. Proceedings of the Second International Congr~s of Human Genetics, Rome 1961. ['IENNINGSEN K. : Blood Grouping in Cases of Disputed Paternity in Denmark.

Methods of Forensic Science Vol. II, 1963.