Low Genetic Variations Research Articles

Draft Genome of Akame (Lates Japonicus) Reveals Possible Genetic Mechanisms for Long-Term Persistence and Adaptive Evolution with Low Genetic Diversity.

It is known that some endangered species have persisted for thousands of years despite their very small effective population sizes and low levels of genetic polymorphisms. To understand the genetic mechanisms of long-term persistence in threatened species, we determined the whole genome sequences of akame (Lates japonicus), which has survived for a long time with extremely low genetic variations. Genome-wide heterozygosity in akame was estimated to be 3.3 to 3.4 × 10-4/bp, one of the smallest values in teleost fishes. Analysis of demographic history revealed that the effective population size in akame was around 1,000 from 30,000 years ago to the recent past. The relatively high ratio of nonsynonymous to synonymous heterozygosity in akame indicated an increased genetic load. However, a detailed analysis of genetic diversity in the akame genome revealed that multiple genomic regions, including genes involved in immunity, synaptic development, and olfactory sensory systems, have retained relatively high nucleotide polymorphisms. This implies that the akame genome has preserved the functional genetic variations by balancing selection, to avoid a reduction in viability and loss of adaptive potential. Analysis of synonymous and nonsynonymous nucleotide substitution rates has detected signs of positive selection in many akame genes, suggesting adaptive evolution to temperate waters after the speciation of akame and its close relative, barramundi (Lates calcarifer). Our results indicate that the functional genetic diversity likely contributed to the long-term persistence of this species by avoiding the harmful effects of the population size reduction.

Genetic variations in NLRP3 and NLRP12 genes in adult-onset patients with autoinflammatory diseases: a comparative study.

Cryopyrin-associated periodic syndrome or NLRP3-associated autoinflammatory disease (NLRP3-AID) and NLRP12-AID are both Mendelian disorders with autosomal dominant inheritance. Both diseases are rare, primarily reported in the pediatric population, and are thought to be phenotypically indistinguishable. We provide the largest cohort of adult-onset patients and compared these diseases and the gene variant frequency to population controls. A cohort of adult patients with AIDs were retrospectively studied. All underwent molecular testing for periodic fever syndrome gene panels after extensive and negative workups for systemic autoimmune and other related diseases. Patients were divided into Group 1- NLRP3-AID patients with NLRP3 variants (N=15), Group 2- NLRP12-AID with NLRP12 variants (N=14) and Group 3- both NLRP3 and NLRP12 (N=9) variants. Exome sequence data of two large control populations including the ARIC study were used to compare gene variant distribution and frequency. All 38 patients were Caucasian with women accounting for 82%. Median age at diagnosis was 41 ± 23 years and the disease duration at diagnosis was 14 ± 13 years. We identified statistically significant differences between the groups, notably that gastrointestinal symptoms as well as evaluations for same were significantly more frequent in patients with NLRP12 variants, and headaches/dizziness were less common among the NLRP12 patients. Livedo reticularis was noted in four patients, exclusively among NLRP12 carriers. Over 50% of patients in Groups 1 and 2 carry low-frequency disease-associated variants, while the remaining carry rare variants. We unprecedently identified digenic variants, i.e.,the coexistence of NLRP3 and NLRP12, which were either both low frequency or low frequency/rare. Allele frequencies of all variants identified in our cohort were either absent or significantly lower in the control populations, further strengthening the evidence of susceptibility of these variants to SAID phenotypes. Our comparative study shows that both NLRP3-AID and NLRP12-AID share similar clinical phenotypes, yet there are significant differences between them with regard to gastrointestinal and neurological symptoms. A spectrum of high to low genetic variations in both genes can contribute to SAID individually or in combination.

Decreasing genetic connectivity in the endangered tree Magnolia patungensis in fragmented forests

Knowledge of genetic variation and connectivity is of great importance to protect endangered species. The region of East Sichuan and West Hubei in China is the biodiversity center of broad-leaved trees in the world, which experienced severe forest fragmentation during the past several decades. Magnolia patungensis is an endangered horticultural tree species endemic to this area. For 16 microsatellite markers, low genetic variations (HE = 0.228–0.364) and high genetic differentiation (FST = 34.0%, G″ST = 53.4%) were found in the four extant M. patungensis populations. These were explained by the genetic bottleneck, genetic drift, inbreeding and restricted gene flow. The low level of historical gene flow (Nmhis = 0.762) among M. patungensis populations was attributed to its limited dispersal ability of pollens and seeds, and the complex terrains of habitats (high mountains, deep valleys, and dense forests). Lower contemporary gene flow (Nmcon = 0.474) suggested that the gene flow was further hindered by recent habitat fragmentations. As for conservation strategies, all remaining populations should be protected to maximize gene representation of the tree species; the artificial pollination is recommended within each population in order to increase seed setting.

Molecular analysis of mitochondrial cytochrome oxidase I gene of Aedes aegypti L. mosquitoes

Abstract Aedes aegypti is the most important arboviral vector worldwide. Recent studies reported that genetic variations and gene flow among same mosquito species is responsible for different disease transmission rate. Hence, to understand the relationship between genetic diversity and disease transmission potential, study on genetic variations among mosquito populations is essential. The aim of present study was to investigate the genetic variations of Ae. aegypti targeting COI gene from nine villages of Jalna District, Maharashtra and three laboratory strains originated from Aurangabad, Delhi and transgenic OX513A strain imported from OXITEC, UK. OX513A strain consists of a self-limiting dominant lethal gene construct intended for its use in suppression of Ae. aegypti population by sustained male adult releases in the environment. Mosquito eggs from field and laboratory strains were reared to adults and identified on the basis of morphological characteristics followed by COI gene sequence. Result of MSA and haplotype analysis revealed low genetic variations among field samples and Aurangabad strain, belonged to two haplotypes (H1 and H2) except Ramkheda village represented by separate haplotype H3. Other laboratory DEL strain and transgenic OX513A have great genetic variability to all isolates and have a separate haplotypes H4 and H5. Similar results were observed in phylogenetic analysis. Our observation of phylogenies revealed close relationship among the DEL and transgenic strain OX513A with few Indian and worldwide isolates. The information on genetic variability of mosquito population could help to understand and design the strategies for risk mitigation and effective implementation of new vector control tools like genetically modified mosquitoes.

Abstract CT148: Small molecule immune-modulator icaritin: Safety, durable survival and inflammation-immune biomarkers in advanced hepatocellular carcinoma

Abstract Objectives: Hepatocellular carcinoma (HCC) was characterized with high heterogeneity and immune “tolerogenic”. Despite of immune checkpoint inhibitors have demonstrated promising results with improved overall survival. Novel small molecule-based immune therapies with high safety profiles might be particularly needed for advanced HCC patients. The purpose of this Phase II study is to explore the safety, clinical activities and treatment associated inflammation-immune biomarkers of icaritin in advanced HCC. Methods: Major eligibility criteria include histologically confirmed unresectable, HCC patients with Child-Pugh Class A or B liver function. Total of 70 advanced HCC patients were enrolled and administrated with 600 mg b.i.d. Primary endpoints were TTP, and secondary endpoints were safety, OS, and DCR. Local disease control was defined as no progressive disease (PD) by RECIST. Kaplan-Meier analysis was utilized for OS assessment. Inflammation-Immune biomarkers NLR, PLR, cytokines, baseline expression of checkpoint/immune gene panel including PD-L1/L2, TIM3, IDO, HLA were evaluated by Nanostring and NGS technologies, retrospectively. Results: There was no ≥ grade III drug related AE observed in all enrolled 70 advanced HCC patients. Objective response evaluation in per-protocol population showed PR (1.6%), SD (32.8%) and PD (59.0%) and median overall survival (OS) 254day (95% CI, 172-296). DCR was achieved 34.4% (95% CI, 22.7-47.7%); Median OS for the PD-L1-positive (n=9) and negative (n=24) subgroups were 389 (95% CI, 80-522) vs. 286.5days (95%CI, 135-482), for IL-6-advantage (n=28) and disadvantage (n=16) subgroups were 328.5 (95% CI, 277-566) vs. 168 days (95% CI, 135-482), for IL-8 low (n=22) and high (n=22) subgroups were 475.5(95% CI, 309-NA) vs. 175days (95% CI, 135-295), respectively. Overall survival was significantly associated with patient genetic profiles such as neo-antigen, bacterial and viral DNA inserts. Conclusion: Icaritin has demonstrated its favorable clinical safety and preliminary immune-modulation efficacy. Potential baseline immune biomarkers to predict the improved OS were suggested including immune cell PD-L1 expression, low level peripheral IL-8, PLR, neoantigen and infection-associated genetic variations. Both safety and immune-response efficacy are warranted for the further Phase III validation. Citation Format: Shu-Kui Qin, Qing Li, Jianmin Xu, Jun Liang, Ying Cheng, Shu Li, Limin Zheng, Bin Ye, Kun Meng, Yan Sun. Small molecule immune-modulator icaritin: Safety, durable survival and inflammation-immune biomarkers in advanced hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT148.

Evaluation of non-linear models for genetic parameters estimation of growth curve traits in Kermani sheep.

In the present study, 10,116 body weight-age records were measured on 2537 Kermani lambs. The records were collected from Kermani Sheep Breeding Station, located in Shahrbabak city, Kerman Province, south-eastern part of Iran, between 1993 and 2013 and used for evaluation of non-linear models describing growth curve from birth to yearling age and estimation of genetic parameters for growth curve traits in Kermani sheep. Six non-linear models including Brody, negative exponential, von Bertalanffy, Richards, Verhulst, and Gompertz were compared applying Akaike's information criterion (AIC), root mean square error (RMSE) and Durbin-Watson statistic (DW) for determining the most appropriate model describing the growth curve in Kermani sheep. The von Bertalanffy model showed the lowest AIC and RMSE among the tested models. Furthermore, positive autocorrelations were found between residuals under the all tested model with the lowest value under the von Bertalanffy model. Therefore, von Bertalanffy model was selected as the best one for describing growth curve in Kermani sheep. A multivariate animal model was used for genetic analysis of the growth curve traits including parameters A (estimated mature weight), B (an integration constant related to initial animal weight), K (maturation rate), inflection age (IA), and inflection weight (IW) under a Bayesian approach. Posterior means for heritability estimates of A, B, K, IA, and IW were significant values of 0.10, 0.03, 0.04, 0.15, and 0.10, respectively. The parameter A had significant and positive genetic and phenotypic correlations with parameters B, IA, and IW. The posterior means for genetic and phenotypic correlations between parameters A and K were negative estimates of - 0.32 and - 0.22, respectively, implied that the lambs with slower maturation rate had higher mature weight. Positive and medium estimates were obtained for posterior means of phenotypic (0.31) and genetic (0.35) correlations between B and K. The posterior means for phenotypic and genetic correlations of B with IA and IW were not statistically significant. High and positive estimates were obtained for posterior means of genetic (0.6) and phenotypic (0.84) correlations between IA and IW. Generally, von Bertalanffy model showed high level of adequacy for describing the growth curve in Kermani sheep. Low additive genetic variations were found for all the studied growth curve traits. Therefore, the traits highly influenced by environmental which necessitate improving environmental influencing factors on the studied traits for achieving desired shape of growth curve and developing an efficient breeding strategy in Kermani sheep.

Prioritizing candidate genes post-GWAS using multiple sources of data for mastitis resistance in dairy cattle

BackgroundImproving resistance to mastitis, one of the costliest diseases in dairy production, has become an important objective in dairy cattle breeding. However, mastitis resistance is influenced by many genes involved in multiple processes, including the response to infection, inflammation, and post-infection healing. Low genetic heritability, environmental variations, and farm management differences further complicate the identification of links between genetic variants and mastitis resistance. Consequently, studies of the genetics of variation in mastitis resistance in dairy cattle lack agreement about the responsible genes.ResultsWe associated 15,552,968 imputed whole-genome sequencing markers for 5147 Nordic Holstein cattle with mastitis resistance in a genome-wide association study (GWAS). Next, we augmented P-values for markers in genes in the associated regions using Gene Ontology terms, Kyoto Encyclopedia of Genes and Genomes pathway analysis, and mammalian phenotype database. To confirm results of gene-based analyses, we used gene expression data from E. coli-challenged cow udders. We identified 22 independent quantitative trait loci (QTL) that collectively explained 14% of the variance in breeding values for resistance to clinical mastitis (CM). Using association test statistics with multiple pieces of independent information on gene function and differential expression during bacterial infection, we suggested putative causal genes with biological relevance for 12 QTL affecting resistance to CM in dairy cattle.ConclusionCombining information on the nearest positional genes, gene-based analyses, and differential gene expression data from RNA-seq, we identified putative causal genes (candidate genes with biological evidence) in QTL for mastitis resistance in Nordic Holstein cattle. The same strategy can be applied for other traits.

Novel risk genes identified in a genome-wide association study for coronary artery disease in patients with type 1 diabetes

BackgroundPatients with type 1 diabetes are more at risk of coronary artery disease than the general population. Although evidence points to a genetic risk there have been no study investigating genetic risk factors of coronary artery disease specific to individuals with type 1 diabetes. To identify low frequency and common genetic variations associated with coronary artery disease in populations of individuals with type 1 diabetes.MethodsA two-stage genome wide association study was conducted. The discovery phase involved the meta-analysis of three genome-wide association cohorts totaling 434 patients with type 1 diabetes and coronary artery disease (cases) and 3123 T1D individuals with no evidence of coronary artery disease (controls). Replication of the top association signals (p < 10−5) was performed in five additional independent cohorts totaling 585 cases and 2612 controls.ResultsOne locus (rs115829748, located upstream of the MAP1B gene) reached the statistical threshold of 5 × 10−8 for genome-wide significance but did not replicate. Nevertheless, three single nucleotide polymorphisms provided suggestive evidence for association with coronary artery disease in the combined studies: CDK18 rs138760780 (OR = 2.60 95% confidence interval [1.75–3.85], p = 2.02 × 10−6), FAM189A2 rs12344245 (OR = 1.85 [1.41–2.43], p = 8.52 × 10−6) and PKD1 rs116092985 (OR = 1.53 [1.27–1.85], p = 1.01 × 10−5). In addition, our analyses suggested that genetic variations at the ANKS1A, COL4A2 and APOE loci previously found associated with coronary artery disease in the general population could have stronger effects in patients with type 1 diabetes.ConclusionsThis study suggests three novel candidate genes for coronary artery disease in the subgroup of patients affected with type 1 diabetes. The detected associations deserve to be definitively validated in additional epidemiological studies.

Abstract 3628: Improving sequencing quality of libraries prepared from FFPE DNA

Abstract Targeted cancer therapy based on genomic alterations can be remarkably effective, and has made significant strides with the recent advances in next-generation sequencing (NGS) technology. Although samples of blood and other bodily fluids are being actively explored for early disease diagnosis and treatment monitoring, DNA isolated from FFPE samples is currently the main source for NGS-based cancer profiling in clinical settings. Unfortunately, sequencing DNA from FFPE samples is challenging due to limited quantities and poor quality, a result of DNA damage incurred during fixation and storage. Artifacts associated with FFPE DNA have limited the mutation detection sensitivity to ≥ 5% mutant allele frequency (Frampton et al, Nature Biotechnology 2013), which would unfortunately leave many low-abundance genetic variants of clinical significance undetected. For example, clinical resistance-causing KIT and EGFR mutations can be present in tumors at levels &amp;lt;&amp;lt; 1% (Milbury et al, Clin. Chem. 2012). In this study, we investigated the effects of DNA repair and different sample handling workflows on sequencing quality of libraries prepared from FFPE samples. Careful analysis of sequencing data showed that base calling qualities for all 4 bases are improved, and aberrant G:C to A:T mutations were significantly reduced upon DNA repair. Because the large majority of mutations encountered in human tumors are G:C to A:T mutations (Greenman, C. Nature 2007), we expect that lowering the damage induced background noise of FFPE DNA would allow more reliable detection of clinically important, actionable mutations at lower abundance. In addition, we observed specific sequencing artifacts associated with the method of handling FFPE samples and have since identified effective measurements to avoid such artifacts. We expect that these improvements in sequencing quality of FFPE samples would ultimately enable more sensitive and robust detection of many low level genetic variations in clinically and biologically relevant cancer genes. Citation Format: pingfang liu, Lixin Chen, Laurence Ettwiller, Christine Sumner, Fiona J. Stewart, Eileen T. Dimalanta, Theodore B. Davis, Evans C. Thomas. Improving sequencing quality of libraries prepared from FFPE DNA. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3628.

Molecular identification of mango hoppers infesting mango trees in Punjab through DNA barcoding

Hoppers belonging to Amritodus spp. and Idioscopus spp. have been reported infesting mango trees in India. In this study, the mango hoppers were collected from Patiala (Nabha), Jalandhar and Ludhiana districts of Punjab for their molecular identification using DNA barcoding. The mitochondrial cytochrome oxidase I (mtCOI) gene from these samples was PCR amplified, cloned in vector and sequenced. The DNA sequences obtained were subjected to analysis through BLASTn programme of NCBI and all three samples were identified as Amritodus atkinsoni with 99% similarity of mtCOI gene sequence. Sequence alignment of 624 bp mtCOI of Amritodus populations showed the changes in nucleotides at 4 different positions. The phylogenetic tree was prepared for mtCOI gene sequences of different populations (number) of A. atkinsoni (1), A. brevistylus (2), Idioscopus niveosparus (1), I. nagpurensis (3) and I. clypealis (1) and populations from Punjab. The tree revealed two Clades, i.e. first corresponding to A. atkinsonii and A. brevistylus, while, Clade 2 consist of three species of Idioscopus with three sub-clusters for each I. clypealis, I. niveosparus and I. nagpurensis. Nucleotide pairwise distances ranged from 0.002 to 0.199. The analysis revealed very low genetic variations among the south and north Indian populations of A. atkinsoni.

Genome-Wide Association Study on Male Genital Shape and Size in Drosophila melanogaster.

Male genital morphology of animals with internal fertilization and promiscuous mating systems have been one of the most diverse and rapidly evolving morphological traits. The male genital morphology in general is known to have low phenotypic and genetic variations, but the genetic basis of the male genital variation remains unclear. Drosophila melanogaster and its closely related species are morphologically very similar, but the shapes of the posterior lobe, a cuticular projection on the male genital arch are distinct from each other, representing a model system for studying the genetic basis of male genital morphology. In this study, we used highly inbred whole genome sequenced strains of D. melanogaster to perform genome wide association analysis on posterior lobe morphology. We quantified the outline shape of posterior lobes with Fourier coefficients obtained from elliptic Fourier analysis and performed principal component analysis, and posterior lobe size. The first and second principal components (PC1 and PC2) explained approximately 88% of the total variation of the posterior lobe shape. We then examined the association between the principal component scores and posterior lobe size and 1902142 single nucleotide polymorphisms (SNPs). As a result, we obtained 15, 14 and 15 SNPs for PC1, PC2 and posterior lobe size with P-values smaller than 10-5. Based on the location of the SNPs, 13, 13 and six protein coding genes were identified as potential candidates for PC1, PC2 and posterior lobe size, respectively. In addition to the previous findings showing that the intraspecific posterior shape variation are regulated by multiple QTL with strong effects, the present study suggests that the intraspecific variation may be under polygenic regulation with a number of loci with small effects. Further studies are required for investigating whether these candidate genes are responsible for the intraspecific posterior lobe shape variation.

Genetic Variation and Population Differentiation in a Medical Herb Houttuynia cordata in China Revealed by Inter-Simple Sequence Repeats (ISSRs)

Houttuynia cordata is an important traditional Chinese herb with unresolved genetics and taxonomy, which lead to potential problems in the conservation and utilization of the resource. Inter-simple sequence repeat (ISSR) markers were used to assess the level and distribution of genetic diversity in 226 individuals from 15 populations of H. cordata in China. ISSR analysis revealed low genetic variations within populations but high genetic differentiations among populations. This genetic structure probably mainly reflects the historical association among populations. Genetic cluster analysis showed that the basal clade is composed of populations from Southwest China, and the other populations have continuous and eastward distributions. The structure of genetic diversity in H. cordata demonstrated that this species might have survived in Southwest China during the glacial age, and subsequently experienced an eastern postglacial expansion. Based on the results of genetic analysis, it was proposed that as many as possible targeted populations for conservation be included.

MOLECULAR GENETIC CHARACTERIZATION FOR TWO EGYPATIAN GOAT BREEDS

Two Egyptian goat breeds (Baladi and Barki) were characterized using biochemical (SDS-PAGE and Native-PAGE) and molecular genetics (RAPD-PCR) techniques. Ten individuals from each breed were blood sampled. SDS-protein profiles for Barki breed showed lower percentage of similarity (82%) than Baladi breed (91%) within each one of them, while Native-PAGE analysis showed a high homogeneity value within each of the studied goat breeds. Moreover, the mean of the band frequencies averages within Baladi and Barki goat breeds based on SDS-PAGE were 0.88 and 0.77, respectively. RAPD analysis using 10 random primers showed high similarity average values of each breed for all used primers which were 0.85 and 0.83 for Baladi and Barki breeds, respectively, which indicates the presence of low genetic variations within the studied breeds. However, the similarity average value of the two tested breeds for all used primers was 0.84, which also indicating the presence of low genetic variations within the studied breeds.

GENETIC CHARACTERIZATION OF SYRIAN ERWINIA AMYLOVORA STRAINS BY AMPLIFIED FRAGMENT LENGTH POLYMORPHISM TECHNIQUE

Thirty Erwinia amylovora strains, collected from the main rosaceous crop-growing regions of Syria, were chosen as representatives of all major pathogenicity groups and were genetically studied by AFLP. Eight primer combinations were utilized and approximately 300 scorable bands in total were generated. Based on similarity coefficient, E. amylovora strains were placed into a main cluster containing two sub-clusters, indicating very low genetic variations among the studied pathogen. The existence of two plasmids, pEA29 (present in nearly all E. amylovora isolates) and pEL60 (present mainly in Lebanese strains), was confirmed using multiplex PCR in all tested Syrian E. amylovora strains, indicating that Lebanese and Syrian isolates may share a common origin.

Molecular epidemiological investigation of infectious hypodermal and hematopoietic necrosis virus and Taura syndrome virus in Penaeus Vannamei cultured in China

The Infectious hypodermal and hematopoietic necrosis virus (IHHNV) and Taura syndrome virus (TSV) are two important shrimp viruses in cultured shrimp in America. These two viruses were transmitted to China at the beginning of the 21st century. In this study, 214 shrimp samples of Penaeus vannamei were collected from seven different areas of China and tested by PCR for IHHNV and TSV infection. The results showed that there were a high prevalence of IHHNV (65.42%) and low prevalence of TSV (3.27%) in the tested samples. Several samples were found to be co-infected with these two viruses. A 3 kb fragment of 7 positive IHHNV samples and a structure protein region (ORF2) of three TSV positive samples were amplified and sequenced. The sequence comparison indicated that both IHHNV and TSV sequenced in China have a low genetic variations compared with the prototype IHHNV and TSV from Hawaii. Phylogenetic analysis showed that TSV isolates were clustered into two groups, Asia and America group, which was genetically correlated to geographic distribution.

Genome-Wide Linkage Scan of Common Stroke in Families From Northern Sweden

Taking advantage of low genetic variations in northern Sweden, we performed a genome-wide linkage scan to investigate the susceptibility loci for common forms of stroke. Fifty-six families, containing multiple cases of stroke and whose data had been previously used to replicate linkage to the phosphodiesterase 4D locus on chromosome 5q, were genotyped in a genome-wide scan. Fine mapping was performed, and subsequently 53 additional families from the same region were genotyped over the candidate regions. Linkage calculations were performed by using 3 different disease models, from a very broad (all stroke cases defined by World Health Organization MONICA criteria) to a narrower (ischemic stroke only) stroke phenotype. With all models, nonparametric multipoint linkage analysis yielded allele-sharing log of the odds (LOD) scores >1.2 at 9 locations: 1p34, 5q13, 7q35, 9q22, 9q34, 13q32, 14q32, 18p11, and 20q13. The highest allele-sharing LOD scores were obtained on chromosomes 5q (previously reported), 1p (LOD=2.09), and 18p (LOD=2.14). Fine mapping resulted in increased allele-sharing LOD scores for chromosome 5q (previously reported) and 9q22 (LOD=1.56), but all others decreased. Combining these initial results with a subsequent analysis of 53 additional families, we obtained the highest allele-sharing LOD scores on chromosomes 5q, 13q, and 18p, although none reached the initial genome-wide allele-sharing LOD scores. Genetic analysis of stroke in families from northern Sweden did not identify any new major stroke loci. This indicates that multiple minor susceptibility loci in addition to the previously known locus on chromosome 5 could contribute to the disease.

Sequence variation and genetic diversity in the giant panda

About 336-444 bp mitochondrial D-loop region and tRNA gene were sequenced for 40 individuals of the giant panda which were collected from Mabian, Meigu, Yuexi, Baoxing, Pingwu, Qingchuan, Nanping and Baishuijiang, respectively. 9 haplotypes were found in 21 founders. The results showed that the giant panda has low genetic variations, and that there is no notable genetic isolation among geographical populations. The ancestor of the living giant panda population perhaps appeared in the late Pleistocene, and unfortunately, might have suffered bottleneck attacks. Afterwards, its genetic diversity seemed to recover to some extent.