Genotypic Disequilibrium Research Articles

Genetic associations and parent-of-origin effects of PVRL1 in non-syndromic cleft lip with or without cleft palate across multiple ethnic populations.

This study investigated the associations of PVRL1 gene variants with non-syndromic cleft lip with or without cleft palate (NSCL/P) by evaluating transmission distortion and parent-of-origin (POO) effects in multiple ethnic populations. We conducted allelic and genotypic transmission disequilibrium tests (TDT) on 10 single-nucleotide variants (SNVs) in PVRL1 using data from 142 Korean families with an affected child. POO effects were analyzed using the POO likelihood ratio test, comparing transmission rates of maternally and paternally inherited alleles. To assess generalizability and ethnic heterogeneity, we compared results from Korean families with data from the Center for Craniofacial and Dental Genetics, which included 2,226 individuals from 497 European and 245 Asian trios. TDT analysis identified significant over-transmission of the rs7940667 (G361V) C allele in Korean families (p=0.007), a finding replicated in both Asian (p=6.5×10-7) and European families (p=1.6×10-10). Eight SNVs showed strong TDT evidence in larger Asian and European datasets after multiple comparison corrections (p<0.0073). Of these, 4 SNVs (rs7940667, rs7103685, rs7129848, and rs4409845) showed particularly robust association (p<5×10-8). POO analysis revealed significant maternal over-transmission of the rs10790330-A allele in Korean families (p=0.044). This finding was replicated in European families (p=9.0×10-4). Additionally, 3 other SNVs, rs7129848 (p=0.001) and the linked SNVs rs3935406 and rs10892434 (p=0.025), exhibited maternal over-transmission in the validation datasets. Our findings provide robust evidence supporting the associations of PVRL1 variants with NSCL/P susceptibility. Further research is necessary to explore the potential clinical applications of these findings.

First report of structural characteristics and polymorphisms of the prion protein gene in raccoon dogs: The possibility of prion disease-resistance.

Prion diseases are fatal degenerative encephalopathies caused by misfolded prion protein (PrPSc) converted from normal prion protein (PrPC). Previous studies have reported that genetic polymorphisms of the prion protein gene (PRNP) play a critical role in susceptibility to prion diseases. In addition, prion disease-resistant animals showed unique structural features of prion protein (PrP) related to species-specific amino acids. However, investigations of genetic polymorphisms of the PRNP gene and structural characteristics of PrP have not been performed in raccoon dogs thus far. We investigated genetic polymorphisms of PRNP in 87 raccoon dogs using amplicon sequencing and analyzed the genotype, allele, haplotype frequencies, and linkage disequilibrium (LD) using Haploview version 4.2. In addition, we performed phylogenetic analysis and multiple sequence alignment (MSA) using MEGA X version 10.1.8 and Clustal X version 2.1, respectively. We estimated the impact of raccoon dog and Canidae family-specific amino acids using PolyPhen-2, PROVEAN, and AMYCO. Furthermore, we analyzed the effect of raccoon dog and Canidae family-specific amino acids using the AlphaFold2 and Swiss-PdbViewer programs. We found 4 novel single nucleotide polymorphisms (SNPs) of the raccoon dog PRNP gene. In addition, the raccoon dog PrP showed 99.61% identity and the closest genetic distance to dog PrP. Among the substitutions of Canidae-specific amino acids with interspecific amino acids, D163N showed increased amyloidogenic propensity, and R181H showed alterations of hydrogen bonds. Furthermore, electrostatic potentials were changed according to the substitutions of D163N and R181H. By comparing PrP between raccoon dogs and raccoons, R168K and K224R were found to be related to changes in hydrogen bonds, and K224R altered the electrostatic potential of raccoon dog PrP. In the present study, we first reported 4 novel synonymous SNPs of the raccoon dog PRNP gene. We also identified that the PrP of raccoon dog has high homology (99.61%) with PrP of dog, which is a prion-resistant animal. In addition, raccoon dog PrP-specific amino acids are related to low amyloid propensity and inherent characteristics of 3D structure of raccoon dog PrP compared to the PrP of prion-susceptible species.

Pathway analysis identified a significant association between cell-cell adherens junctions-related genes and non-syndromic cleft lip/palate in 895 Asian case-parent trios

ObjectivesTo study the association between the seven cell-cell adherens junctions (AJs) -related genes (CDH1, CTNND1, CTNNA1, ESRP1, ESRP2, PLEKHA5, and PLEKHA7) and non-syndromic cleft lip with or without cleft palate (NSCL/P) in the Asian population. DesignThe study included 895 NSCL/P case-parent trios of Asian ethnicity drawn from an international consortium established for a genome-wide association study. We performed association analysis by applying the genotypic transmission disequilibrium test for each of the 144 single nucleotide polymorphisms (SNPs), the versatile gene-based association study for the combined effects of all SNPs, all in or around the seven target genes, and the versatile pathway-based approach for the combined effects of these seven target genes, consecutively. ResultsIn our analysis, we found neither a significant SNP-based nor gene-based association with NSCL/P for any of the 144 relevant SNPs or the seven target genes. However, novel evidence of a significant association (P = 6.00 × 10−6) with NSCL/P was observed in the combined effects of these seven target genes in the versatile pathway-based analysis. ConclusionsOur results were consistent with the findings of previously published human sequencing studies and reinforced the role of these cell-cell AJs-related genes in the pathogenesis of NSCL/P that may be replicated using data from other genome-wide association studies. This pathway approach better reflects our current understanding of the biological mechanisms underlying the aetiology of NSCL/P.

Isolation of 27 polymorphic nuclear microsatellite markers for Roupala montana var. brasiliensis (Proteaceae).

Microsatellite primers pairs were developed for the Neotropical tree Roupala montana var. brasiliensis for use in studies on genetic diversity, mating system, and gene flow. Forty-two primer pairs were developed, resulting in 27 polymorphic loci, with two to 27 alleles per locus. The primer pairs were validated against 34 R. montana var. brasiliensis adult trees from four populations. The observed (H o) and expected (H e)heterozygosities ranged among loci from 0.061 to 0.930 (mean of 0.544) and from 0.116 to 0.950 (mean of 0.700), respectively. Null alleles were observed for ten loci. No genotypic linkage disequilibrium was detected in any pair of loci. This set of loci is suitable for population genetic studies of the species.

Polygene: Population genetics analyses for autopolyploids based on allelic phenotypes

Abstract Polyploidy has appeared in almost every ancestral plant lineage, and in extant species, occurs frequently. When present, polyploidy presents problems for genetic data analysis, which are caused by both genotypic ambiguities and double‐reduction. To address these problems, we developed a new software package, polygene, which enables the estimation of genotypic frequencies for a number of polysomic inheritance models. Specifically, polygene obtains posterior probabilities for genotypes hidden within allelic phenotypes. Comprehensive modes of genetic analyses are provided by polygene, which include genetic diversity analysis, tests for allelic phenotypic or genotypic distributions, linkage disequilibrium and genetic differentiation, genetic distance analysis, principal coordinates analysis, hierarchical clustering analysis, individual inbreeding coefficient estimation, individual heterozygosity index estimation, population assignment, pairwise relatedness estimation, parentage analysis, analysis of molecular variance and Bayesian clustering. polygene enables easy and convenient allelic phenotype‐ or genotype‐based analysis for both autopolyploids and diploids. polygene will thus facilitate molecular ecology research involving autopolyploids.

Genetic variation in KRTAP11.1 gene of suri alpaca (Vicugna pacos) from Puno - Peru

The objective of this study was to identify genetic single nucleotide polymorphisms (SNPs) in the coding region of the KRTAP11.1 gene from the Suri alpaca population from Puno, Peru. Genomic DNA (n = 119) was used to amplify the 636 bp fragment of the coding region from the KRTAP11.1 gene. The polymerase chain reaction products of the KRTAP11.1 gene were sequenced by both strands and polymorphism type SNPs were identified. All SNPs (n = 3) were in Hardy-Weinberg equilibrium and had a high level of genotypic linkage disequilibrium with the presence of two haplotypes. All genetic polymorphisms generate non-synonymous amino acids changes: SNP 110 T>G (Ser>Ala), SNP 363 T>G (Phe>Cys) and SNP 375 A>C (Tyr>Ser). The results indicated the presence of moderate genetic diversity in the coding region of the KRTAP11.1 gene from the Suri alpaca population.

Validation of microsatellite loci for Balfourodendron riedelianum through analysis of Mendelian inheritance, genetic linkage, and genotypic linkage disequilibrium

Abstract Balfourodendron riedelianum is a tropical tree endemic to the Atlantic Forest biome that is currently endangered due to forest fragmentation and extensive exploitation. Three populations of the species are conserved ex situ in a provenance and progeny test at the Luiz Antônio Experimental Station, São Paulo State, Brazil. To verify if seven microsatellite loci developed for the species can be used as genetic markers in analyses focused on conservation and sustainable use strategies, leaf tissue samples were collected from the three provenances and from 17 seed trees in one provenance. We analyzed Mendelian inheritance and genetic linkage for the 17 seed trees and genotypic linkage disequilibrium for individuals from the three provenances. For six of the seven loci analyzed, all 17 seed trees showed heterozygosity. The inheritance and genetic linkage analyses were performed using respective locus, while the genotypic linkage disequilibrium analysis was performed for the seven loci. After Bonferroni correction, none of the 75 tests showed deviation from Mendelian segregation and genetic linkage, nor did we detect genotypic linkage disequilibrium. The results suggest that six of the seven loci can be used for population genetics studies on B. riedelianum.

GENETIC DIVERSITY AND MATING SYSTEM OF Rhizophora mangle L. (RHIZOPHORACEAE) IN NORTHERN BRAZIL REVEALED BY MICROSATELLITE ANALYSIS

ABSTRACT Rhizophora mangle L. (Rhizophoraceae) grows on aerial roots, which emerge above the water level, giving stands of this tree the characteristic “mangrove” appearance. To produce in situ and ex situ information for genetic conservation programs for this species, we investigated the genetic diversity and mating system of one R. mangle population. We sampled 30 adult trees and a total of 349 seeds in Northern Brazil. We genotyped all adult trees and seeds with four microsatellite loci. The average fixation index was -0.222 for adult trees and 0.030 for seeds. The multilocus outcrossing rate (t m =0.921) was significantly lower than unity (1.0). There was no substantial evidence of null alleles nor genotypic disequilibrium among the loci. The combined power to exclude the first parent probability was 0.921. The average coancestry coefficient (=0.180) was similar to that expected for half-sib progenies (=0.125). Thus, the number of adult trees necessary for seed collection to obtain progeny arrays with an effective size of 150 was estimated to be 62. In conclusion, this study produced important information for the management and conservation of R. mangle and will contribute to conservation and management programs for this species.

Mendelian inheritance, genetic linkage, and genotypic disequilibrium for nine microsatellite loci in Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae).

Cariniana estrellensis is one of the largest trees found in Brazilian tropical forests. The species is typical of advanced stages of succession, characteristic of climax forests, and essential in genetic conservation and environmental restoration plans. In this study, we assessed Mendelian inheritance, genetic linkage, and genotypic disequilibrium in nine microsatellite loci for a C. estrellensis population. We sampled and genotyped 285 adult trees and collected seeds from 20 trees in a fragmented forest landscape in Brazil. Based on maternal genotypes and their seeds, we found no deviation from the expected 1:1 Mendelian segregation and no genetic linkage between pairwise loci. However, for adults, genotypic disequilibrium was detected for four pairs of loci, suggesting that this result was not caused by genetic linkage. Based on these results, we analyzed microsatellite loci that are suitable for use in population genetic studies assessing genetic diversity, mating system, and gene flow in C. estrellensis populations.

Analysis of Mendelian inheritance and genetic linkage in microsatellite loci of Eucalyptus urophylla S.T. Blake.

Eucalyptus urophylla is an important species in the Brazilian forest sector due to its rapid growth rates and resistance to disease. The aim of this study was to verify Mendelian inheritance, genetic linkage, and genotypic disequilibrium for 15 microsatellite loci, with the goal of producing a robust set of genetic markers. Mendelian inheritance and genetic linkage analyses were carried out using genotypes from maternal trees, and their open-pollinated seeds and genotypic disequilibrium were assessed using adult trees. By comparing heterozygous maternal genotypes and their seeds, we found no significant deviations from the expected 1:1 Mendelian segregation and the expected 1:1:1:1 segregation hypothesis for pairwise loci. For adult trees, we did not find strong evidence of genotypic imbalance for pairwise loci. Our results indicated that the analyzed set of microsatellite loci could be used to carry out analyses of genetic diversity, mating system, and parentage in E. urophylla.

Development and characterization of microsatellite loci for the Neotropical orchid Trichocentrum pumilum

Abstract Studies of genetic diversity and structure are key elements in designing effective in situ and ex situ management plans, especially for species experiencing forest fragmentation. To investigate the level of genetic diversity in populations of Trichocentrum pumilum, eight polymorphic microsatellite loci were developed and used for genotyping 96 specimens from four disturbed populations. Low genetic diversity within populations was found (average number of alleles per locus ranging from 3.75 to 4.25, observed and expected heterozygosities from 0.238 to 0.333 and from 0.450 to 0.482, respectively). The fixation index () ranged from 0.35 to 0.47, with significant values for all populations. No genotypic disequilibrium was detected. A mixed breeding system was found through an apparent outcrossing rate estimate. Our results suggest that these microsatellite loci are suitable for genetic studies of this species, showing low within population genetic diversity and moderate structure for T. pumilum populations.

The algorithm for Alzheimer risk assessment based on APOE promoter polymorphisms.

BackgroundOver the past two decades, the APOE gene and its polymorphisms have been among the most studied risk factors of Alzheimer disease (AD) development; yet, there are discrepancies between various studies regarding their impact. For this reason, the evaluation of the APOE genotype has not been included in the current European Federation of Neurological Societies guidelines for AD diagnosis and management. This aim of this study was to add to this discussion by assessing the possible influence of multiple polymorphisms in the promoter region of the APOE gene and genotypes of its allele E on the risk for dementia.MethodsWe performed a comprehensive analysis of APOE gene polymorphisms, assessed the detected genotypes and correlated molecular findings with serum apolipoprotein E concentrations. The study comprised 110 patients with AD and 110 age-matched healthy individuals from the Polish population.ResultsFour polymorphisms of the APOE gene had minor allele frequency exceeding 5 % and were included in the analysis: −491A/T (rs449647), −427T/C (rs769446), −219T/G (rs405509) in the promoter region and +113G/C (rs440446) in intron 1. A protective effect of the −219G allele on AD development was observed. Also, the −491T and −219G alleles were found to be underrepresented in the carriers of the APOE E4 variant. On the basis of the genotype and linkage disequilibrium studies, a relative score was attributed to given genotypes with respect to the estimated probability of their protective effects against AD, giving rise to the ‘preventive score’. This ‘preventive score’, based on the total sums of the relative scores, expresses the protective effect deriving from the synergistic action of individual single-nucleotide polymorphisms. The ‘preventive score’ was identified as an independent predictive factor.ConclusionsWe propose a novel, more complex approach to AD risk assessment based on the additive effect of multiple polymorphic loci within the APOE promoter region, which on their own may have too weak an impact to reach the level of significance. This has potentially practical implications, as it may help to improve the informative potential of APOE testing in a clinical setting. Subsequent studies of the proposed system in large, multi-ethnic cohorts are necessary for its validation and to assess its potential practical value for clinical applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s13195-016-0187-9) contains supplementary material, which is available to authorized users.

Characterization of nine microsatellite loci for Dicrocoelium dendriticum, an emerging liver fluke of ungulates in North America, and their use to detect clonemates and random mating

This study characterizes polymorphic microsatellite loci from adults of the liver fluke Dicrocoelium dendriticum sampled from a population of sympatric beef cattle and wapiti in a region of emergence in southern Alberta, Canada. We also scrutinized the markers to validate their use in studying the population genetics of this complex life cycle parasite. Among the nine loci described, four deviated significantly from Hardy Weinberg Equilibrium (HWE) due to technical artefacts. The remaining five loci were in HWE. These five provided sufficient resolution to identify clonemates produced from the obligate asexual reproduction phase of the life cycle in snails and to assess the impact of non-random transmission of clonemates on measures of FIS, FST and genotypic disequilibrium. Excluding clonemates, we show that the sub-population of worms was in HWE, that average FIS within hosts was 0.003 (p=0.4922) and that there was no population genetic structure among hosts FST=0.001 (p=0.3243). These markers will be useful for studies of Dicrocoelium dendriticum ecology, transmission, and evolution.

Short Communication Mendelian inheritance, linkage, and genotypic disequilibrium in microsatellite loci of Hymenaea stigonocarpa Mart. ex Hayne (Fabaceae-Caesalpinioideae).

Hymenaea stigonocarpa is a deciduous and monoecious Neotropical tree species pollinated by bats. Due to overexploitation and habitat destruction, the population size has drastically diminished in nature. No previous study has investigated Mendelian inheritance, linkage, and genotypic disequilibrium in the available microsatellite markers in this species. So, our aim was to estimate these parameters using six microsatellite loci in a sample of 470 adults and 219 juveniles from two populations of H. stigonocarpa. In addition, 30 seeds per tree from 35 seed-trees were collected. Each seed was kept record of the seed-trees and fruit origin. Based on the six microsatellite loci, we found that only 10.6% of the cases showed significant deviations from Mendelian segregation and 15.3% showed linkage. We detected no evidence of genotypic disequilibrium between the loci in the adult trees or juveniles. Thus, our results suggest that these loci can be used with great accuracy in future genetic analyses of H. stigonocarpa populations.

Characterization of 17 novel microsatellite loci in the Nile monitor (Varanus niloticus) via 454 pyrosequencing

We used 454 pyrosequencing to characterize 17 novel microsatellite loci from the Nile monitor (Varanus niloticus), using samples from an invasive population in the US state of Florida. These markers were screened for variation in 40 individuals from the City of Cape Coral. Observed heterozygosity ranged from 0.18 to 0.73 (mean ± SE = 0.46 ± 0.06) and the number of alleles per locus ranged from 1 to 4 (mean ± SE = 2.5 ± 0.2). Preliminary genotyping of samples from populations in West Palm Beach and Homestead revealed two loci (Mon6andMon15) that are monomorphic in Cape Coral, but polymorphic in these other two populations. We found no statistical departures from Hardy-Weinberg equilibrium or evidence of null alleles. However, there was statistical evidence for genotypic disequilibrium betweenMon1-Mon14andMon3-Mon8. BLASTn searches of NCBI’s nr/nt database identified four microsatellites containing 454 fragments that exhibit substantial sequence similarity to loci in other reptilian genomes, suggesting these markers should be prioritized by researchers interested in cross-amplification in other varanids. The resources we have developed will enable investigations of the population genetic dynamics of invasive Nile monitors in Florida and may facilitate studies within this species native range.

Development of twelve novel microsatellite markers in the medicinal mushroom Cordyceps militaris (Ascomycota: Clavicipitaceae) for its strain identification and genetic analysis

AbstractCordyceps militaris (a caterpillar fungus), which belongs to the class Ascomycetes, has extensively been used for medicinal purposes in East Asia. Here, we isolated and characterized 12 microsatellite loci from the medicinal mushroom, C. militaris. Twenty‐nine individual samples were taken from a single locality in southwestern Korea and used to characterize the developed markers. The number of alleles of these loci ranged from two to 13 (mean allelic richness = 6.44). Observed heterozygosity and expected heterozygosity in the population ranged from 0.035 to 0.880 and from 0.035 to 0.886, respectively. Five of 12 loci significantly deviated from Hardy–Weinberg Equilibrium, most likely due to heterozygote deficiency caused by inbreeding. Tests of genotypic linkage disequilibrium between the 12 loci showed no significant association of alleles. These microsatellite markers will provide valuable tools for genetic analyses for the strain identification of C. militaris as well as for its resource conservation.

Mendelian inheritance, genetic linkage, and genotypic disequilibrium at microsatellite loci in Genipa americana L. (Rubiaceae).

Genipa americana is a tropical tree species that is widely distributed in the humid tropical and subtropical regions of Central and South America. This study investigated Mendelian inheritance, genetic linkage, and genotypic disequilibrium at six microsatellite loci developed for G. americana. Adult trees (188) and regenerants (163) were sampled and genotyped in a fragmented population of the species. We also genotyped open-pollinated seeds from 12 seed-trees during reproductive events in 2010 and 2011. Significant deviations from the expected 1:1 Mendelian segregation were detected in 29.5% of the tests. Significant genetic linkage between pairwise loci was detected in 54.4% of the tests, but no genotypic disequilibrium was detected between pairwise loci for adult trees and regenerants. Overall, the results indicate that the six loci analyzed may be used in studies of G. americana's genetic diversity and structure, its mating system, and in parentage analyses.

Development of polymorphic microsatellite markers of Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae), a North American pest invading Asia.

Microsatellite markers were developed for epidemiological studies on the black locust gall midge Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae), a native North America pest introduced to Europe and Asia. Polymorphism at each locus was tested on 68 individuals from six populations reared from infected host leaves of Robinia pseudoacacia L. collected in China. Fourteen loci were found to be polymorphic, with the number of alleles ranging from 3 to 10. The observed heterozygosity varied evenly from 0.2667 to 0.6540. For populations, the observed heterozygosity ranged from 0.1429 to 1.000. The allele frequency of the predominant allele varied from 0.250 to 0.500. All loci with negative FST values indicated heterozygote excess in each locus with six populations. Of 14 loci, four were observed to have FST values up to 0.05, which indicated negligible genetic differentiation within the population. Significant deviations (P < 0.05) from the expected Hardy–Weinberg equilibrium, as evaluated using the Markov chain algorithm for each locus and for all six populations, were observed, and genotypic linkage disequilibrium was clearly detected. These markers represent a useful tool to design strategies for integrated pest management and in the study of population evolution in this important introduced pest.

Characterization of 14 novel microsatellite loci in the Argentine black and white tegu (Salvator merianae) via 454 pyrosequencing

We have developed 14 novel microsatellite loci for the Argentine black and white tegu (Salvator merianae), using samples from invasive populations from the US state of Florida. Pyrosequencing was used to identify 3154 potentially amplifiable microsatellite loci and to subsequently develop 14 informative markers. These 14 markers were screened for variation in 40 individuals from Miami-Dade County, Florida. All loci were polymorphic and contained between 2 and 4 alleles per locus (mean ± SE = 2.71 ± 0.24), with observed heterozygosity ranging from 0.00 to 0.88 (mean ± SE = 0.38 ± 0.07). Four of the loci (Teg4, Teg5, Teg17, Teg19) significantly deviated from Hardy-Weinberg proportions and three of these loci (Teg4, Teg5, Teg19) showed evidence of null alleles. In addition, there was statistical evidence for genotypic disequilibrium between Teg14 and Teg19. BLASTn searches of NCBI’s ‘nr/nt’ database using microsatellite containing 454 fragments as queries were largely uninformative; however, it is likely that some of these markers will be of utility in S. merinae’s native range.

Investigating the Mendelian inheritance, genetic linkage, and genotypic disequilibrium for ten microsatellite loci of Araucaria angustifolia

Abstract Araucaria angustifolia is a dioecious and wind pollinated conifer that typically occurs in higher attitudes of Southern Brazil. After a significant reduction of its population during the twentieth century, public policies have enabled natural populations to recover. As new studies focus on the genetics of the species it is important to investigate Mendelian inheritance, genetic linkage, and genotypic disequilibrium for the microsatellite loci developed for the species. Here we analyze ten microsatellite loci developed for A. angustifolia by genotyping 295 adult trees and 13 open pollinated progenies from a forest fragment in Santa Catarina, Brazil. The likelihood G-test shows a perfect 1:1 Mendelian segregation for all ten loci, indicating that these molecular markers are genetic markers. Significant genetic linkage between pairwise loci was detected in only 3% of the tests, suggesting that these loci are not located in the same linkage groups within the chromosomes. However, genotypic disequilibrium was detected in 51% of pairwise loci for adult trees, probably due to the strong spatial genetic structure of the population. Our results indicate that the ten loci analyzed can be used in studies on genetic diversity and structure, mating system, and gene flow of the species.