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Sephardic signature in haplogroup T mitochondrial DNA.

ABSTRACT: A rare combination of mutations within mitochondrial DNA subhaplogroup T2e is identified as affiliated with Sephardic Jews, a group that has received relatively little attention. Four investigations were pursued: Search of the motif in 250?000 control region records across 8 databases, comparison of frequencies of T subhaplogroups (T1, T2b, T2c, T2e, T4, T(*)) across 11 diverse populations, creation of a phylogenic median-joining network from public T2e control region entries, and analysis of one Sephardic mitochondrial full genomic sequence with the motif. It was found that the rare motif belonged only to Sephardic descendents (Turkey, Bulgaria), to inhabitants of North American regions known for secret Spanish-Jewish colonization, or were consistent with Sephardic ancestry. The incidence of subhaplogroup T2e decreased from the Western Arabian Peninsula to Italy to Spain and into Western Europe. The ratio of sister subhaplogroups T2e to T2b was found to vary 40-fold across populations from a low in the British Isles to a high in Saudi Arabia with the ratio in Sephardim more similar to Saudi Arabia, Egypt, and Italy than to hosts Spain and Portugal. Coding region mutations of 2308G and 14499T may locate the Sephardic signature within T2e, but additional samples and reworking of current T2e phylogenetic branch structure is needed. The Sephardic Turkish community has a less pronounced founder effect than some Ashkenazi groups considered singly (eg, Polish), but other comparisons of interest await comparable averaging. Registries of signatures will benefit the study of populations with a large number of smaller-size founders.

SUBMITTER: Bedford FL

PROVIDER: S-EPMC3306851 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Sephardic signature in haplogroup T mitochondrial DNA.

Bedford Felice L FL

European journal of human genetics : EJHG 20111123 4

A rare combination of mutations within mitochondrial DNA subhaplogroup T2e is identified as affiliated with Sephardic Jews, a group that has received relatively little attention. Four investigations were pursued: Search of the motif in 250 000 control region records across 8 databases, comparison of frequencies of T subhaplogroups (T1, T2b, T2c, T2e, T4, T(*)) across 11 diverse populations, creation of a phylogenic median-joining network from public T2e control region entries, and analysis of on ...[more]

PMID: 22108605

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Project description:BackgroundThe Strait of Gibraltar separating the Iberian Peninsula from North Africa is thought to be a stronger barrier to gene flow for male than for female lineages. However, the recent subdivision of the haplogroup H at mitochondrial DNA (mtDNA) level has revealed greater genetic differentiation among geographic regions than previously detected. The dissection of the mtDNA haplogroup H in North Africa, and its comparison with the Iberian Peninsula and Near-East profiles would help clarify the relative affinities among these regions.ResultsLike the Iberian Peninsula, the dominant mtDNA haplogroup H subgroups in North Africa are H1 (42%) and H3 (13%). The similarity between these regions is stronger in the North-West edge affecting mainly Moroccan Arabs, West Saharans and Mauritanians, and decreases eastwards probably due to gene flow from Near East as attested for the higher frequencies of H4, H5, H7, H8 and H11 subgroups. Moroccan Berbers show stronger affinities with Tunisian and Tunisian Berbers than with Moroccan Arabs. Coalescence ages for H1 (11 +/- 2 ky) and H3 (11 +/- 4 ky) in North Africa point to the possibility of a late Palaeolithic settlement for these lineages similar to those found for other mtDNA haplogroups. Total and partial mtDNA genomic sequencing unveiled stronger mtDNA differentiation among regions than previously found using HVSI mtDNA based analysis.ConclusionThe subdivision of the mtDNA haplogroup H in North Africa has confirmed that the genetic differentiation found among Western and Eastern populations is mainly due to geographical rather than cultural barriers. It also shows that the historical Arabian role on the region had more a cultural than a demic effect. Whole mtDNA sequencing of identical H haplotypes based on HVSI and RFLP information has unveiled additional mtDNA differences between North African and Iberian Peninsula lineages, pointing to an older mtDNA genetic flow between regions than previously thought. Based on this new information, it seems that the Strait of Gibraltar barrier affected both male and female gene flow in a similar fashion.

Project description:Importance:Autism spectrum disorders (ASD) are characterized by impairments in social interaction, communication, and repetitive or restrictive behavior. Although multiple physiologic and biochemical studies have reported defects in mitochondrial oxidative phosphorylation in patients with ASD, the role of mitochondrial DNA (mtDNA) variation has remained relatively unexplored. Objective:To assess what impact mitochondrial lineages encompassing ancient mtDNA functional polymorphisms, termed haplogroups, have on ASD risk. Design, Setting, and Participants:In this cohort study, individuals with autism and their families were studied using the Autism Genetic Resource Exchange cohort genome-wide association studies data previously generated at the Children's Hospital of Philadelphia. From October 2010 to January 2017, we analyzed the data and used the mtDNA single-nucleotide polymorphisms interrogated by the Illumina HumanHap 550 chip to determine the mtDNA haplogroups of the individuals. Taking into account the familial structure of the Autism Genetic Resource Exchange data, we then determined whether the mtDNA haplogroups correlate with ASD risk. Main Outcomes and Measures:Odds ratios of mitochondrial haplogroup as predictors of ASD risk. Results:Of 1624 patients with autism included in this study, 1299 were boys (80%) and 325 were girls (20%). Families in the Autism Genetic Resource Exchange collection (933 families, encompassing 4041 individuals: 1624 patients with ASD and 2417 healthy parents and siblings) had been previously recruited in the United States with no restrictions on age, sex, race/ethnicity, or socioeconomic status. Relative to the most common European haplogroup HHV, European haplogroups I, J, K, O-X, T, and U were associated with increased risk of ASD, as were Asian and Native American haplogroups A and M, with odds ratios ranging from 1.55 (95% CI, 1.16-2.06) to 2.18 (95% CI, 1.59-3) (adjusted P < .04). Hence, mtDNA haplogroup variation is an important risk factor for ASD. Conclusions and Relevance:Because haplogroups I, J, K, O-X, T, and U encompass 55% of the European population, mtDNA lineages must make a significant contribution to overall ASD risk.

Project description:Previous studies have suggested that mitochondrial DNA (mtDNA) variants are associated with multiple sclerosis (MS), a complex neurodegenerative immune-mediated disease of the central nervous system. Since mtDNA is maternally inherited without recombination, specific mtDNA variants defining genetic background are associated with the susceptibility to human diseases. To assess the contribution of mtDNA haplogroups to the predisposition of MS in an Arab population, we analysed sequencing data of mitochondrial genomes from 47 native Saudi Arab individuals including 23 patients with relapsing-remitting MS (RRMS) and 24 healthy controls. All patients and controls could be classified into ten haplogroups. The European-specific haplogroup U was more prevalent in patients than in the controls (26.1% vs. 4.2%), whereas haplogroup T was only present in patients and haplogroups HV and N were only found in controls. Haplogroup U was significantly association with increased risk of MS (odds ratio = 6.26, p<0.05), although the association did not maintain significance after adjustment for multiple comparisons. Haplotype U was more prevalent in patients with younger age of onset (p = 0.006), but there was no relationship between haplotype U and disease severity, disease duration or EDSS and age-matched carriers and non-carriers of haplogroup U (p>0.05). Definition site of haplogroup U include the variant m.12308A>G in MT-TL2 gene which was found to affect highly conserved position within the variable arm of tRNALeu(CUN) and thus may impact mitochondrial protein synthesis, and two other variants namely m.11467A>G in MT-ND4 gene and m.12372G>A in MT-ND5 gene which were previously linked with mitochondrial function. Despite the small number of subjects, which may limit the statistical power of the study, our results showed for the first time a possible contribution of haplogroup U to the predisposition to MS in an Arab population. These findings warrant further validation in a large cohort to distinguish a genuine effect specific to MS from a chance finding due to small sampling.

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Sephardic signature in haplogroup T mitochondrial DNA.

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Sephardic signature in haplogroup T mitochondrial DNA.

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