Davide Pettener

The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods

Abstract n A recent workshop entitled “The Family Name as Socio-Cultural Feature and Genetic Metaphor: From Concepts to Methods” was held in Paris in December 2010, sponsored by the French National Centre for Scientific Research (CNRS) and by the journal Human Biology. This workshop was intended to foster a debate on questions related to the family names and to compare different multidisciplinary approaches involving geneticists, historians, geographers, sociologists and social anthropologists. This collective paper presents a collection of selected communications.

Mitochondrial DNA Variability in the Titicaca Basin: Matches and Mismatches with Linguistics and Ethnohistory

The Titicaca basin was the cradle of some of the major complex societies of pre‐Columbian South America and is today home to three surviving native languages: Quechua, Aymara, and Uro. This study seeks to contribute to reconstructing the population prehistory of the region, by providing a first genetic profile of its inhabitants, set also into the wider context of South American genetic background.

Long-Range Comparison between Genes and Languages Based on Syntactic Distances

Objective: To propose a new approach for comparing genetic and linguistic diversity in populations belonging to distantly related groups. Background: Comparisons of linguistic and genetic differences have proved powerful tools to reconstruct human demographic history. Current models assume on both sides that similarities reflect either descent from common ancestry or the balance between isolation and contact. Most linguistic phylogenies are ultimately based on lexical evidence (roughly, words and morphemes with their sounds and meanings). However, measures of lexical divergence are reliable only for closely related languages, thus large-scale comparisons of genetic and linguistic diversity have appeared problematic so far. Methods: Syntax (abstract rules to combine words into sentences) appears more measurable, universally comparable, and stable than the lexicon, and hence certain syntactic similarities might reflect deeper linguistic relationships, such as those between distant language families. In this study, we for the first time compared genetic data to a matrix of syntactic differences among selected populations of three continents. Results: Comparing two databases of microsatellite (Short Tandem Repeat) markers and Single Nucleotides Polymorphisms (SNPs), with a linguistic matrix based on the values of 62 grammatical parameters, we show that there is indeed a correlation of syntactic and genetic distances. We also identified a few outliers and suggest a possible interpretation of the overall pattern. Conclusions: These results strongly support the possibility of better investigating population history by combining genetic data with linguistic information of a new type, provided by a theoretically more sophisticated method to assess the relationships between distantly related languages and language families.

Discordant patterns of mtDNA and ethno-linguistic variation in 14 Iranian Ethnic groups.

Background/Aims: Present-day Iran has long represented a natural hub for the expansion of human genes and cultures. That being so, the overlapping of prehistoric and more recent demographic events interacting at different time scales with geographical and cultural barriers has yielded a tangled patchwork of anthropological types within this narrow area. This study aims to comprehensively evaluate this ethnic mosaic by depicting a fine-grained picture of the Iranian mitochondrial landscape. Methods: mtDNA variability at both HVS-I and coding regions was surveyed in 718 unrelated individuals belonging to 14 Iranian ethnic groups characterized by different languages, religions and patterns of subsistence. Results: A discordant pattern of high ethno-linguistic and low mtDNA heterogeneity was observed for the whole examined Iranian sample. Geographical factors and cultural/linguistic differences actually represented barriers to matrilineal gene flow only for the Baloch, Lur from Yasouj, Zoroastrian and Jewish groups, for which unusual reduced levels of mtDNA variability and high inter-population distances were found. Conclusion: Deep rooting genealogies and endogamy in a few of the examined ethnic groups might have preserved ancestral lineages that can be representative of Proto-Indo-Iranian or prehistoric mitochondrial profiles which survived relatively recent external contributions to the Iranian gene pool.

Mitochondrial Polymorphisms Are Associated Both with Increased and Decreased Longevity

Previous work compared frequency of longevity-associated polymorphisms (LAPS) in long-lived individuals and in controls from the general population (primarily in Europe and Japan), suggesting the polymorphisms are responsible for unusual longevity. However, individuals from the general population are not the control group for long-lived subjects because both were born in different periods. We report results of a project which collected mtDNA from living subjects in Costa Rica, and traced back their maternal genealogy. Since mtDNA does not recombine and its probability of mutation is low, we can assume that the maternal ancestors had the same mtDNA of their descendants. We compared the longevity of individuals with LAPS with the longevity of controls born in the same time period. We did not confirm previous associations for several markers, but found that the 5178A mutation in haplogroup D is associated with decreased longevity, whereas the 150T mutation is associated with increased longevity. These associations however, are not significant for all time periods under study. While our data confirm that mtDNA make up affects longevity, they also indicate that the time period in which a person was born had a much greater impact on longevity than presence or absence of a marker.

Linking Italy and the Balkans. A Y-chromosome perspective from the Arbereshe of Calabria

Background: The Arbereshe are an Albanian-speaking ethno-linguistic minority who settled in Calabria (southern Italy) about five centuries ago. Aim: This study aims to clarify the genetic relationships between Italy and the Balkans through analysis of Y-chromosome variability in a peculiar case study, the Arbereshe. Subject and methods: Founder surnames were used as a means to identify a sample of individuals that might trace back to the Albanians at the time of their establishment in Italy. These results were compared with data of more than 1000 individuals from Italy and the Balkans. Results: The distributions of haplogroups (defined using 31 UEPs) and haplotypes (12 STRs) show that the Italian and Balkan populations are clearly divergent from each other. Within this genetic landscape, the Arbereshe are characterized by two peculiarities: (a) they are a clear outlier in the Italian genetic background, showing a strong genetic affinity with southern Balkans populations; and (b) they retain a high degree of genetic diversity. Conclusion: These results support the hypothesis that the surname-chosen Arbereshe are representative of the Y-chromosome genetic variability of the Albanian founder population. Accordingly, the Arbereshe genetic structure can contribute to the interpretation of the recent biological history of the southern Balkans. Intra-haplogroup analyses suggest that this area may have experienced important changes in the last five centuries, resulting in a marked increase in the frequency of haplogroups I2a and J2.

Genetic analysis of the presumptive blood from Louis XVI, king of France

A text on a pyrographically decorated gourd dated to 1793 explains that it contains a handkerchief dipped with the blood of Louis XVI, king of France, after his execution. Biochemical analyses confirmed that the material contained within the gourd was blood. The mitochondrial DNA (mtDNA) hypervariable region 1 (HVR1) and 2 (HVR2), the Y-chromosome STR profile, some autosomal STR markers and a SNP in HERC2 gene associated to blue eyes, were retrieved, and some results independently replicated in two different laboratories. The uncommon mtDNA sequence retrieved can be attributed to a N1b haplotype, while the novel Y-chromosome haplotype belongs to haplogroup G2a. The HERC2 gene showed that the subject analyzed was a heterozygote, which is compatible with a blue-eyed person, as king Louis XVI was. To confirm the identity of the subject, an analysis of the dried heart of his son, Louis XVII, could be undertaken.

Are ethnic minorities synonymous for genetic isolates? Comparing Walser and Romance populations in the Upper Lys Valley (Western Alps).

Cultural differences between neighbouring populations are often said to give rise to reproductive barriers. For ethnic minorities, these barriers can easily result in genetic isolation. In this study, we analyse the surname structure of the Walser of the upper Lys Valley, a German-speaking ethnic minority in the Italian Western Alps, to better understand the relationships between linguistic and genetic isolation. Analyses were based on 1713 marriages registered from 1838 to 1938 in four villages of the valley: three Walser communities (Issime, Gressoney-Saint-Jean, Gressoney-La-Trinité) and the Romance community of Gaby. The results show that endogamy and inbreeding are lower than in other Italian linguistic minorities, with the exception of Gaby, whose values rank among the highest ever found in Italy. Compared to the Walser communities Gaby behaves as an outgroup and has an almost exclusively autochthonous surname set. The latter aspect is also true, but to a lesser extent, for the Walser villages, in particular for Issime on the one hand and Gressoney-Saint-Jean and Gressoney-La-Trinité on the other. These findings strongly suggest that the Walser communities ethnic minority status is not associated with genetic isolation, whereas genetic isolation was found in the linguistically non-isolated Gaby. Finally, our results are consistent with two independent late medieval migration events at the origin of these Walser settlements.

Dissecting a human isolate: Novel sampling criteria for analysis of the genetic structure of the Val di Scalve (Italian Pre-Alps)

Abstract Background: The choice of criteria for correct DNA sampling in isolated populations is often affected by ambiguities, despite its importance in medical and anthropological genetics. Aim: We propose a novel biodemographic approach to the study of isolates based on surname analysis and migration matrices, and we apply it to a candidate isolated population: the Val di Scalve (Italian Pre-Alps). Methods: Kinship matrices and self-organizing maps (SOMs) were applied to information extracted from 2870 marriage records relative to the years 1866–1935. Results: The Val di Scalve shows the typical genetic trademarks of an isolate at least up to the first half of the 20th century. Furthermore, the area was characterized by differential mobility patterns between males and females, consistent with the virilocal migration model. These data suggest reliable criteria for an efficient DNA sampling design by (a) detecting the units of analysis to be investigated (internal population subdivisions); (b) maximizing the number of paternal lineages in the sample for Y-chromosome studies (surnames); and (c) calculating the most convenient sample size. Conclusion: The surname-based sampling procedure can be exported and applied to larger and non-isolated populations.

Diversity in the Glucose Transporter-4 Gene (SLC2A4) in Humans Reflects the Action of Natural Selection along the Old-World Primates Evolution

Background Glucose is an important source of energy for living organisms. In vertebrates it is ingested with the diet and transported into the cells by conserved mechanisms and molecules, such as the trans-membrane Glucose Transporters (GLUTs). Members of this family have tissue specific expression, biochemical properties and physiologic functions that together regulate glucose levels and distribution. GLUT4 –coded by SLC2A4 (17p13) is an insulin-sensitive transporter with a critical role in glucose homeostasis and diabetes pathogenesis, preferentially expressed in the adipose tissue, heart muscle and skeletal muscle. We tested the hypothesis that natural selection acted on SLC2A4. Methodology/Principal Findings We re-sequenced SLC2A4 and genotyped 104 SNPs along a ∼1 Mb region flanking this gene in 102 ethnically diverse individuals. Across the studied populations (African, European, Asian and Latin-American), all the eight common SNPs are concentrated in the N-terminal region upstream of exon 7 (∼3700 bp), while the C-terminal region downstream of intron 6 (∼2600 bp) harbors only 6 singletons, a pattern that is not compatible with neutrality for this part of the gene. Tests of neutrality based on comparative genomics suggest that: (1) episodes of natural selection (likely a selective sweep) predating the coalescent of human lineages, within the last 25 million years, account for the observed reduced diversity downstream of intron 6 and, (2) the target of natural selection may not be in the SLC2A4 coding sequence. Conclusions We propose that the contrast in the pattern of genetic variation between the N-terminal and C-terminal regions are signatures of the action of natural selection and thus follow-up studies should investigate the functional importance of differnet regions of the SLC2A4 gene.