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38 COELIAC DISEASE IN THE SAHARAWI
Dimension 2
1.4
Sub Saharian Africa
SEN
FIL
Asia
1
+ Europe and N. Africa
+
+
Gre
+
+
0.6
+
Sard
Bulg
+
+
+
HONG KONG
0.2
+
+ + Cre
ETH
+
-0.2
+ ++ ++ +
+ Rom
CHI
JAP
+
+
Ita
+
Tun
-0.6
Tur
POL
+
Mor
+
+
Fra
Spa +
-1
S AFR
+
GAB
+ Cze
Alg+
Nw Rus
Saha
+
+
Nor + Gb
-1.4
+
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
Dimension 1
Fig. 1. Multidimentional scaling of 26 populations tested for HLA DRB1-DQA1-DQB1
haplotypes. The first dimension splits Eastern and Western world populations. The
Caucasians are closely grouped and located in the African range of variability. The second
dimension explains the diversity of the Sub-Saharan African and Caucasian groups, which
include the North-African and Saharawi samples.
On the right box, European and North African patterns were enlarged.
30 31 32-33 34
Population samples: ALG, Algerian ; BULG, Bulgarian ; CHI, Chinese ; CRE, Cretan ;
35 36 37
CZE, Czech ; ETH, Ethiopian ; FIL, Filipino ; FRA, French; ITA, Italian; RUM, Rumanian;
38 39 40
S-AFR, South-African; SEN, Senegalese; SPA, Spanish ; GAB, Gabonese ; GB, British ;
41 32 42 43
GRE, Greek ; HONG KONG, Hong-Kong ; JAP, Japanese ; MOR, Moroccan ; NOR,
44 45 46 47
Norwegian ; NW-RUS, North-Western Russian ; POL, Polynesian ; TUN, Tunisian ; TUR,
48 49
Turkish ;SARD, Sardinian and in circle font the Saharawi (current work).
asset of a given population are on a much larger scale in comparison to those required to
change environmental factors, i.e. the socalled “gene-environment evolutionary tempo
mismatch”.
Finally there is another important lesson coming from CD to understand the bases of
other multifactorial traits. CD tells us that some of the environmental factors involved
in triggering these complex traits could be nearly ubiquitous (gluten). It might be
extremely difficult to identify them in diseases in which the target organ is not able to
regenerate when the trigger factor is removed.
Acknowledgements
We wish to thank Stefano De Virgiliis, M.Doloretta Macis, Mauro Congia, Michael
Whalen , Laura Morelli, Patrizia Zavattari and Antonio Cao for advice and support.
References
1. Mäki M, Collin P. Coeliac disease. Lancet 1997; 349: 755-9.
2. Risch N. Assessing the role of HLA-linked and unlinked determinants of disease. Am