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VOL. 72 (1), 37-47, 2006 MITOCHONDRIAL LINEAGES DISTRIBUTION IN THE SPANISH...

this positive effect was related with a particular environment and
nowadays, in other environmental conditions, they may have
different effects on the phenotype (16-18).

Several major haplogroups (H, V, J, T, U, I, W, X) were described
in Western Eurasian individuals (19) and their frequencies were
very similar all around Europe (20). The increased interest in
mitochondrial population genetics has made possible to subdivide
these haplogroups in smaller clusters, called subhaplogroups. The
frequency and distribution of these subhaplogroups is not the same
in different European populations (6, 21-23). Similarly to the
haplogroups, some of the mutations defining these subhaplogroups
might have a phenotypic effect and then, they could contribute to
the distinct prevalence of these diseases in different populations (24).

In advance of next epidemiologic studies in the Spanish
population trying to associate phenotypes to mitochondrial genetic
background, we decided to characterize the Spanish population
according to the mitochondrial haplogroups.

MATERIAL AND METHODS

Peripheral blood was collected from 686 unrelated individuals
from Northern and Centre of Spain (Zaragoza and Madrid).

Genomic DNA was extracted by conventional methods (25) and
the samples were haplogrouped by PCR amplification of short
mtDNA fragments, followed by restriction enzyme analysis (RFLP
analysis). We used the haplogrouping strategy from (5) (Table 1).
Hypervariable region I (HVR-I) was sequenced in order to confirm
haplogroups and determine subhaplogroups U. Full description of
oligodeoxynucleotides utilized and PCR amplification conditions are
available upon request.

Results and differences in diverse mitochondrial variants among
populations were assessed by the Chi square independence test from
contingency tables and post hoc analysis. Significant differences were
assumed when P = 0.05.

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