Polymorphism of the mitochondrial DNA control region in Italians

Tagliabracci, Adriano; Turchi, Chiara; Buscemi, Loredana; Sassaroli, Corrado

doi:10.1007/s004140000168

Cited by 43 publications

(36 citation statements)

References 27 publications

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“…Consistent with our results, these studies commented on heteroplasmy being a notable occurrence at 16 311 bp (site B) 23 and at 16 093 bp (site D) where it reached a population frequency of 5%. 17 Levels of heteroplasmic variant were almost identical in placental samples and cord blood (r 2 ¼ 0.99), although cord blood was only available on 13 samples.…”

Section: Discussionsupporting

confidence: 92%

Mosaicism for mitochondrial DNA polymorphic variants in placenta has implications for the feasibility of prenatal diagnosis in mtDNA diseases

et al. 2006

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Women who have had a child with mitochondrial DNA (mtDNA) disease need to know the risk of recurrence, but this risk is difficult to estimate because mutant and wild-type (normal) mtDNA coexist in the same person (heteroplasmy). The possibility that a single sample may not reflect the whole organism both impedes prenatal diagnosis of most mtDNA diseases, and suggests radical alternative strategies such as nuclear transfer. We used naturally occurring mtDNA variants to investigate mtDNA segregation in placenta. Using large samples of control placenta, we demonstrated that the level of polymorphic heteroplasmic mtDNA variants is very similar in mother, cord blood and placenta. However, where placental samples were very small (o10 mg) there was clear evidence of variation in the distribution of mtDNA polymorphic variants. We present the first evidence for variation in mutant load, that is, mosaicism for mtDNA polymorphic variants in placenta. This suggests that mtDNA mutants may segregate in placenta and that a single chorionic villous sample (CVS) may be unrepresentative of the whole placenta. Duplicates may be necessary where CVS are small. However, the close correlation of mutant load in maternal, fetal blood and placental mtDNA suggests that the average load in placenta does reflect the load of mutant mtDNA in the baby. Provided that segregation of neutral and pathogenic mtDNA mutants is similar in utero, our results are generally encouraging for developing prenatal diagnosis for mtDNA diseases. Identifying mtDNA segregation in human placenta suggests studies of relevance to placental evolution and to developmental biology.

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Section: Discussionsupporting

confidence: 92%

Mosaicism for mitochondrial DNA polymorphic variants in placenta has implications for the feasibility of prenatal diagnosis in mtDNA diseases

et al. 2006

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“…These sequences represent all European population samples we could locate for the specified regions. In addition to sequences analysed in Helgason et al (2000aHelgason et al ( , 2001, data from the following sources are incorporated: 254 Yugoslavians (M. Harvey, K. Gordon, K. Owens, M. Lee & M.-C. King, GenBank accession numbers AY005495-AY005795), 199 Russians and 436 Poles (Malyarchuk et al 2002), 118 Spanish (Crespillo et al 2001), 241 Portuguese (Pereira et al 2000), 83 Italians (Tagliabracci et al 2001 Abbreviations in column titles are N = sample size, k = number of distinct haplotypes and S = number of polymorphic sites. MPD = mean pairwise differences between all pairs of sequences.…”

Section: Genetic Systems and Population Samplesmentioning

confidence: 99%

“…A set of 7245 HVS1 sequences was analysed between sites 16090-16365 (276 base-pairs). In addition to sequences analysed in Helgason et al (2000aHelgason et al ( , 2001, the following are added: 50 Germans (Baasner et al 1998), 106 Sicilians (Cali et al 2001), 118 Spanish (Crespillo et al 2001), 154 Swiss (DimoSimonin et al 2000, 300 Yugoslavian (see Table 2), 20 Finns and 10 Polish (Jorde et al 2000), 50 Russians, (Malyarchuk & Derenko, 2001), 436 Poles and 201 Russians (Malyarchuk et al 2002), 129 Slovakians (E. Metspalu, T. Kivisild, K. Kaldma, M. Reidla & R. Villems, GenBank accession numbers AJ240164-AJ240292), 74 Norwegians (Passarino et al 2002), 241 Portuguese (Pereira et al 2000), 300 Canary Islanders (Rando et al 1999), 83 Italians (Tagliabracci et al 2001) and 186 Cretans (R. Villems, GenBank accession numbers AJ274757-AJ274942). Sequences that did not completely span the regions defined above were omitted from analysis, and population samples analysed in Helgason et al (2000a) with sample sizes below 70 were excluded.…”

Section: Genetic Systems and Population Samplesmentioning

confidence: 99%

A Reassessment of Genetic Diversity in Icelanders: Strong Evidence from Multiple Loci for Relative Homogeneity Caused by Genetic Drift

Helgason

Nicholson

Stefánsson

et al. 2003

Annals of Human Genetics

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SummaryThere has been some controversy in the literature concerning whether Icelanders are genetically homogenous or heterogeneous relative to other European populations. We reassess this question in the light of large data sets spanning 83 autosomal SNP loci, 14 serogenetic loci, 6622 Y-chromosomes and 3214 sequences from mtDNA hypervariable segments 1 and 2 (HVS1 and HVS2). Our results strongly support the hypothesis that genetic drift, with a consequent loss of variation, has had a greater impact on Icelanders than most other Europeans. We also analyse 7245 HVS1 sequences from 25 European populations. In line with other studies, we observe a deficit of rare HVS1 haplotypes and an excess of intermediate frequency haplotypes in Icelanders compared to most European populations, with some measures of genetic diversity indicating relative heterogeneity and others indicating relative homogeneity of Icelanders. Simulations indicate that genetic drift, and not admixture (as proposed byÁrnason , 2003) is the most likely cause of the atypical Icelandic HVS1 frequency spectrum. These simulations reveal that gene diversity (heterozygosity) and mean pairwise differences are largely insensitive to events in recent population history, while statistics based on the number of haplotypes or segregating sites are much more sensitive. Overall, our analyses strongly indicate that the Icelandic gene pool is less heterogeneous than those of most other European populations.

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“…Data from the following populations were used: 436 Poles and 201 Russians (Malyarchuk et al 2002); 200 Southern Germans (Lutz et al 1998); 101 Austrians (Parson et al 1998); 150 Western Germans (Baasner et al 1998;Baasner & Madea, 2000); 109 North-Western Germans (Pfeiffer et al 1999);192 Finns (Finnilä et al 2001); 30 Bulgarians (Calafell et al 1996); 83 Italians (Tagliabracci et al 2001); 204 French-speaking individuals from France and Switzerland (Rousselet & Mangin, 1998;Dimo-Simonin et al 2000); and 241 Portuguese (Pereira et al 2000).…”

Section: Phylogenetic and Statistical Analysismentioning

confidence: 99%