Multiple sclerosis in Gypsies from southern Spain: prevalence, mitochondrial DNA haplogroups and HLA class II association.

Occasional reports have mentioned the prevalence of multiple sclerosis (MS) among Gypsies, and no studies have examined to date the prevalence of MS or human leukocyte antigen (HLA) genetics associations in the Spanish Gypsy population. We decided to study the prevalence, mitochondrial DNA (mtDNA) haplogroups and HLA class II distribution among gypsies with MS in southern Spain. We searched for Gypsy MS patients and studied HLA class II alleles by polymerase chain reaction with sequence-specific oligonucleotide (PCR/SSO) probe hybridization or sequence-specific primers amplification. An additional study of the mtDNA haplogroups by sequencing of the hypervariable segments of the control region was also performed to provide details of their ethnic origin. Estimated prevalence of MS in the Gypsy population in Malaga was 52/100,000. No significant differences were found in mtDNA between Gypsy MS patients and Gypsy controls. DRB1*1501, DQB1*0602 and DQB1*0608 alleles were the only positive HLA association with MS. The Gypsies in our series have the same anthropological origin as other European gypsy groups, as shown by mtDNA haplogroups. Although interpreted with great caution because of the small sample size, we found that the prevalence of MS in Gypsies in Malaga is not as low as that in Central Europe, although it is significantly less than that found in Caucasians from Spain (75-79/100,000). DQB1*0602 was the strongest positive association found with Gypsy MS patients, and DRB1*1501-DQB1*0602 was the most frequent haplotype in this group.

A signal, from human mtDNA, of postglacial recolonization in Europe.

Mitochondrial HVS-I sequences from 10,365 subjects belonging to 56 populations/geographical regions of western Eurasia and northern Africa were first surveyed for the presence of the T-->C transition at nucleotide position 16298, a mutation which has previously been shown to characterize haplogroup V mtDNAs. All mtDNAs with this mutation were then screened for a number of diagnostic RFLP sites, revealing two major subsets of mtDNAs. One is haplogroup V proper, and the other has been termed "pre*V," since it predates V phylogenetically. The rather uncommon pre*V tends to be scattered throughout Europe (and northwestern Africa), whereas V attains two peaks of frequency: one situated in southwestern Europe and one in the Saami of northern Scandinavia. Geographical distributions and ages support the scenario that pre*V originated in Europe before the Last Glacial Maximum (LGM), whereas the more recently derived haplogroup V arose in a southwestern European refugium soon after the LGM. The arrival of V in eastern/central Europe, however, occurred much later, possibly with (post-)Neolithic contacts. The distribution of haplogroup V mtDNAs in modern European populations would thus, at least in part, reflect the pattern of postglacial human recolonization from that refugium, affecting even the Saami. Overall, the present study shows that the dissection of mtDNA variation into small and well-defined evolutionary units is an essential step in the identification of spatial frequency patterns. Mass screening of a few markers identified using complete mtDNA sequences promises to be an efficient strategy for inferring features of human prehistory.