Distributions of 4-subtree patterns for uniform random unrooted phylogenetic trees.

Tree shape statistics based on peripheral structures have been utilized to study evolutionary mechanisms and inference methods. Partially motivated by a recent study by Pouryahya and Sankoff on modeling the accumulation of subgenomes in the evolution of polyploids, we present the distribution of subtree patterns with four or fewer leaves for the unrooted Proportional to Distinguishable Arrangements (PDA) model. We derive a recursive formula for computing the joint distributions, as well as a Strong Law of Large Numbers and a Central Limit Theorem for the joint distributions. This enables us to confirm several conjectures proposed by Pouryahya and Sankoff, as well as provide some theoretical insights into their observations. Based on their empirical datasets, we demonstrate that the statistical test based on the joint distribution could be more sensitive than those based on one individual subtree pattern to detect the existence of evolutionary forces such as whole genome duplication.

Integrated genomic analyses of cutaneous T-cell lymphomas reveal the molecular bases for disease heterogeneity.

Cutaneous T-cell lymphomas (CTCLs) are a clinically heterogeneous collection of lymphomas of the skin-homing T cell. To identify molecular drivers of disease phenotypes, we assembled representative samples of CTCLs from patients with diverse disease subtypes and stages. Via DNA/RNA-sequencing, immunophenotyping, and ex vivo functional assays, we identified the landscape of putative driver genes, elucidated genetic relationships between CTCLs across disease stages, and inferred molecular subtypes in patients with stage-matched leukemic disease. Collectively, our analysis identified 86 putative driver genes, including 19 genes not previously implicated in this disease. Two mutations have never been described in any cancer. Functionally, multiple mutations augment T-cell receptor-dependent proliferation, highlighting the importance of this pathway in lymphomagenesis. To identify putative genetic causes of disease heterogeneity, we examined the distribution of driver genes across clinical cohorts. There are broad similarities across disease stages. Many driver genes are shared by mycosis fungoides (MF) and Sezary syndrome (SS). However, there are significantly more structural variants in leukemic disease, leading to highly recurrent deletions of putative tumor suppressors that are uncommon in early-stage skin-centered MF. For example, TP53 is deleted in 7% and 87% of MF and SS, respectively. In both human and mouse samples, PD1 mutations drive aggressive behavior. PD1 wild-type lymphomas show features of T-cell exhaustion. PD1 deletions are sufficient to reverse the exhaustion phenotype, promote a FOXM1-driven transcriptional signature, and predict significantly worse survival. Collectively, our findings clarify CTCL genetics and provide novel insights into pathways that drive diverse disease phenotypes.

Distributions of cherries and pitchforks for the Ford model.

Distributional properties of tree shape statistics under random phylogenetic tree models play an important role in investigating the evolutionary forces underlying the observed phylogenies. In this paper, we study two subtree counting statistics, the number of cherries and that of pitchforks for the Ford model, the alpha model introduced by Daniel Ford. It is a one-parameter family of random phylogenetic tree models which includes the proportional to distinguishable arrangement (PDA) and the Yule models, two tree models commonly used in phylogenetics. Based on a non-uniform version of the extended Pólya urn models in which negative entries are permitted for their replacement matrices, we obtain the strong law of large numbers and the central limit theorem for the joint distribution of these two statistics for the Ford model. Furthermore, we derive a recursive formula for computing the exact joint distribution of these two statistics. This leads to exact formulas for their means and higher order asymptotic expansions of their second moments, which allows us to identify a critical parameter value for the correlation between these two statistics. That is, when the number of tree leaves is sufficiently large, they are negatively correlated for 0≤α≤1/2 and positively correlated for 1/2<α<1.

Comprehensive Analysis of Human Subtelomeres by Whole Genome Mapping.

Detailed comprehensive knowledge of the structures of individual long-range telomere-terminal haplotypes are needed to understand their impact on telomere function, and to delineate the population structure and evolution of subtelomere regions. However, the abundance of large evolutionarily recent segmental duplications and high levels of large structural variations have complicated both the mapping and sequence characterization of human subtelomere regions. Here, we use high throughput optical mapping of large single DNA molecules in nanochannel arrays for 154 human genomes from 26 populations to present a comprehensive look at human subtelomere structure and variation. The results catalog many novel long-range subtelomere haplotypes and determine the frequencies and contexts of specific subtelomeric duplicons on each chromosome arm, helping to clarify the currently ambiguous nature of many specific subtelomere structures as represented in the current reference sequence (HG38). The organization and content of some duplicons in subtelomeres appear to show both chromosome arm and population-specific trends. Based upon these trends we estimate a timeline for the spread of these duplication blocks.

Towards a global partnership model in interprofessional education for cross-sector problem-solving.

OBJECTIVES: A partnership model in interprofessional education (IPE) is important in promoting a sense of global citizenship while preparing students for cross-sector problem-solving. However, the literature remains scant in providing useful guidance for the development of an IPE programme co-implemented by external partners. In this pioneering study, we describe the processes of forging global partnerships in co-implementing IPE and evaluate the programme in light of the preliminary data available. METHODS: This study is generally quantitative. We collected data from a total of 747 health and social care students from four higher education institutions. We utilized a descriptive narrative format and a quantitative design to present our experiences of running IPE with external partners and performed independent t-tests and analysis of variance to examine pretest and posttest mean differences in students' data. RESULTS: We identified factors in establishing a cross-institutional IPE programme. These factors include complementarity of expertise, mutual benefits, internet connectivity, interactivity of design, and time difference. We found significant pretest-posttest differences in students' readiness for interprofessional learning (teamwork and collaboration, positive professional identity, roles, and responsibilities). We also found a significant decrease in students' social interaction anxiety after the IPE simulation. CONCLUSIONS: The narrative of our experiences described in this manuscript could be considered by higher education institutions seeking to forge meaningful external partnerships in their effort to establish interprofessional global health education.

Whole-exome sequencing reveals damaging gene variants associated with hypoalphalipoproteinemia.

Low levels of high density lipoprotein-cholesterol (HDL-C) are associated with an elevated risk of arteriosclerotic coronary heart disease. Heritability of HDL-C levels is high. In this research discovery study, we used whole-exome sequencing to identify damaging gene variants that may play significant roles in determining HDL-C levels. We studied 204 individuals with a mean HDL-C level of 27.8 ± 6.4 mg/dl (range: 4-36 mg/dl). Data were analyzed by statistical gene burden testing and by filtering against candidate gene lists. We found 120 occurrences of probably damaging variants (116 heterozygous; four homozygous) among 45 of 104 recognized HDL candidate genes. Those with the highest prevalence of damaging variants were ABCA1 (n = 20), STAB1 (n = 9), OSBPL1A (n = 8), CPS1 (n = 8), CD36 (n = 7), LRP1 (n = 6), ABCA8 (n = 6), GOT2 (n = 5), AMPD3 (n = 5), WWOX (n = 4), and IRS1 (n = 4). Binomial analysis for damaging missense or loss-of-function variants identified the ABCA1 and LDLR genes at genome-wide significance. In conclusion, whole-exome sequencing of individuals with low HDL-C showed the burden of damaging rare variants in the ABCA1 and LDLR genes is particularly high and revealed numerous occurrences in HDL candidate genes, including many genes identified in genome-wide association study reports. Many of these genes are involved in cancer biology, which accords with epidemiologic findings of the association of HDL deficiency with increased risk of cancer, thus presenting a new area of interest in HDL genomics.

Analysis of putative cis-regulatory elements regulating blood pressure variation.

Hundreds of loci have been associated with blood pressure (BP) traits from many genome-wide association studies. We identified an enrichment of these loci in aorta and tibial artery expression quantitative trait loci in our previous work in ~100 000 Genetic Epidemiology Research on Aging study participants. In the present study, we sought to fine-map known loci and identify novel genes by determining putative regulatory regions for these and other tissues relevant to BP. We constructed maps of putative cis-regulatory elements (CREs) using publicly available open chromatin data for the heart, aorta and tibial arteries, and multiple kidney cell types. Variants within these regions may be evaluated quantitatively for their tissue- or cell-type-specific regulatory impact using deltaSVM functional scores, as described in our previous work. We aggregate variants within these putative CREs within 50 Kb of the start or end of 'expressed' genes in these tissues or cell types using public expression data and use deltaSVM scores as weights in the group-wise sequence kernel association test to identify candidates. We test for association with both BP traits and expression within these tissues or cell types of interest and identify the candidates MTHFR, C10orf32, CSK, NOV, ULK4, SDCCAG8, SCAMP5, RPP25, HDGFRP3, VPS37B and PPCDC. Additionally, we examined two known QT interval genes, SCN5A and NOS1AP, in the Atherosclerosis Risk in Communities Study, as a positive control, and observed the expected heart-specific effect. Thus, our method identifies variants and genes for further functional testing using tissue- or cell-type-specific putative regulatory information.

The 22q11 low copy repeats are characterized by unprecedented size and structural variability.

Low copy repeats (LCRs) are recognized as a significant source of genomic instability, driving genome variability and evolution. The Chromosome 22 LCRs (LCR22s) mediate nonallelic homologous recombination (NAHR) leading to the 22q11 deletion syndrome (22q11DS). However, LCR22s are among the most complex regions in the genome, and their structure remains unresolved. The difficulty in generating accurate maps of LCR22s has also hindered localization of the deletion end points in 22q11DS patients. Using fiber FISH and Bionano optical mapping, we assembled LCR22 alleles in 187 cell lines. Our analysis uncovered an unprecedented level of variation in LCR22s, including LCR22A alleles ranging in size from 250 to 2000 kb. Further, the incidence of various LCR22 alleles varied within different populations. Additionally, the analysis of LCR22s in 22q11DS patients and their parents enabled further refinement of the rearrangement site within LCR22A and -D, which flank the 22q11 deletion. The NAHR site was localized to a 160-kb paralog shared between the LCR22A and -D in seven 22q11DS patients. Thus, we present the most comprehensive map of LCR22 variation to date. This will greatly facilitate the investigation of the role of LCR variation as a driver of 22q11 rearrangements and the phenotypic variability among 22q11DS patients.

Investigating rare pathogenic/likely pathogenic exonic variation in bipolar disorder.

Bipolar disorder (BD) is a serious mental illness with substantial common variant heritability. However, the role of rare coding variation in BD is not well established. We examined the protein-coding (exonic) sequences of 3,987 unrelated individuals with BD and 5,322 controls of predominantly European ancestry across four cohorts from the Bipolar Sequencing Consortium (BSC). We assessed the burden of rare, protein-altering, single nucleotide variants classified as pathogenic or likely pathogenic (P-LP) both exome-wide and within several groups of genes with phenotypic or biologic plausibility in BD. While we observed an increased burden of rare coding P-LP variants within 165 genes identified as BD GWAS regions in 3,987 BD cases (meta-analysis OR = 1.9, 95% CI = 1.3-2.8, one-sided p = 6.0 × 10-4), this enrichment did not replicate in an additional 9,929 BD cases and 14,018 controls (OR = 0.9, one-side p = 0.70). Although BD shares common variant heritability with schizophrenia, in the BSC sample we did not observe a significant enrichment of P-LP variants in SCZ GWAS genes, in two classes of neuronal synaptic genes (RBFOX2 and FMRP) associated with SCZ or in loss-of-function intolerant genes. In this study, the largest analysis of exonic variation in BD, individuals with BD do not carry a replicable enrichment of rare P-LP variants across the exome or in any of several groups of genes with biologic plausibility. Moreover, despite a strong shared susceptibility between BD and SCZ through common genetic variation, we do not observe an association between BD risk and rare P-LP coding variants in genes known to modulate risk for SCZ.

The Clinical Sequencing Evidence-Generating Research Consortium: Integrating Genomic Sequencing in Diverse and Medically Underserved Populations.

The Clinical Sequencing Evidence-Generating Research (CSER) consortium, now in its second funding cycle, is investigating the effectiveness of integrating genomic (exome or genome) sequencing into the clinical care of diverse and medically underserved individuals in a variety of healthcare settings and disease states. The consortium comprises a coordinating center, six funded extramural clinical projects, and an ongoing National Human Genome Research Institute (NHGRI) intramural project. Collectively, these projects aim to enroll and sequence over 6,100 participants in four years. At least 60% of participants will be of non-European ancestry or from underserved settings, with the goal of diversifying the populations that are providing an evidence base for genomic medicine. Five of the six clinical projects are enrolling pediatric patients with various phenotypes. One of these five projects is also enrolling couples whose fetus has a structural anomaly, and the sixth project is enrolling adults at risk for hereditary cancer. The ongoing NHGRI intramural project has enrolled primarily healthy adults. Goals of the consortium include assessing the clinical utility of genomic sequencing, exploring medical follow up and cascade testing of relatives, and evaluating patient-provider-laboratory level interactions that influence the use of this technology. The findings from the CSER consortium will offer patients, healthcare systems, and policymakers a clearer understanding of the opportunities and challenges of providing genomic medicine in diverse populations and settings, and contribute evidence toward developing best practices for the delivery of clinically useful and cost-effective genomic sequencing in diverse healthcare settings.

On asymptotic joint distributions of cherries and pitchforks for random phylogenetic trees.

Tree shape statistics provide valuable quantitative insights into evolutionary mechanisms underpinning phylogenetic trees, a commonly used graph representation of evolutionary relationships among taxonomic units ranging from viruses to species. We study two subtree counting statistics, the number of cherries and the number of pitchforks, for random phylogenetic trees generated by two widely used null tree models: the proportional to distinguishable arrangements (PDA) and the Yule-Harding-Kingman (YHK) models. By developing limit theorems for a version of extended Pólya urn models in which negative entries are permitted for their replacement matrices, we deduce the strong laws of large numbers and the central limit theorems for the joint distributions of these two counting statistics for the PDA and the YHK models. Our results indicate that the limiting behaviour of these two statistics, when appropriately scaled using the number of leaves in the underlying trees, is independent of the initial tree used in the tree generating process.

Rubinoboletus ballouii polysaccharides exhibited immunostimulatory activities through toll-like receptor-4 via NF-κB pathway.

The biological activities of water-soluble components of edible mushroom Rubinoboletus ballouii (RB) were seldom reported. Polysaccharides of RB (RBP) were prepared and well-characterized using chemical analyses. The immunomodulatory properties of RBP were investigated using human monocyte-derived dendritic cells (moDC) in vitro, and cyclophosphamide (CTX)-induced immunosuppressive mouse model. Results showed that RBP was found to contain 80.6% (w/w) of neutral sugars including D-fucose, D-mannose, D-glucose and D-galactose (1.7:1.4:1.0:1.8), and 12.5% (w/w) of proteins, which composed of glutamine, threonine, serine, etc. RBP could promote the maturation of moDC and increase the secretion of IL-12p40, IL-10, and TNF-α. Furthermore, the stimulation of IL-12p40 production was inhibited by pretreatment with toll-like receptor (TLR)-4 blocker or NF-κB pathway blocker, suggesting that the activation of moDC by RBP was mediated through NF-κB pathway via TLR-4 receptor. On the other hand, in CTX-treated mice, RBP restored the loss of CD34bright CD45dim hematopoietic stem cells and increased IL-2 production in sera and splenocytes culture supernatant, as well as up-regulated the percentage of CD4+ T helper lymphocyte in mice splenocytes. These findings strongly suggested that RBP are the active ingredients of RB responsible for its immunostimulatory actions and deserved to be further investigated as cancer supplements.

De novo mutation and skewed X-inactivation in girl with BCAP31-related syndrome.

Full genome analysis of a young girl with deafness, dystonia, central hypomyelination, refractory seizure, and fluctuating liver function impairment revealed a heterozygous, de novo variant in the BCAP31 gene on chromosome Xq28 (NM_001256447.2:c.92G>A), mutations of which caused the X-linked recessive severe neurologic disorder deafness, dystonia, and cerebral hypomyelination. Reverse transcription-polymerase chain reaction of the patient's white blood cells showed the absence of wild-type BCAP31 messenger RNA (mRNA) but the presence of two novel BCAP31 mRNAs. The major alternatively spliced mRNA is due to Exon 2 skipping and the utilization of a new initiation site in Exon 3 that leads to a frameshift and truncated transcript while the minor novel mRNA has a 110 nucleotide insertion to Exon 2. Phasing studies showed that the de novo variant arose in the paternal X chromosome. X chromosome inactivation assay was done and confirmed that the patient's maternal X chromosome was preferentially inactivated, providing evidence that the mutated BCAP31 gene was the one predominantly expressed. According to the American College of Medical Genetics and Genomics guideline, this variant is deemed "pathogenic" (PS2, PS3, PM2, PP3, and PP4) and deleterious. This is the first reported female patient in BCAP31-related syndrome resulted from skewed X-inactivation and a de novo mutation in the active X chromosome.

Comparative genome analysis of programmed DNA elimination in nematodes.

Programmed DNA elimination is a developmentally regulated process leading to the reproducible loss of specific genomic sequences. DNA elimination occurs in unicellular ciliates and a variety of metazoans, including invertebrates and vertebrates. In metazoa, DNA elimination typically occurs in somatic cells during early development, leaving the germline genome intact. Reference genomes for metazoa that undergo DNA elimination are not available. Here, we generated germline and somatic reference genome sequences of the DNA eliminating pig parasitic nematode Ascaris suum and the horse parasite Parascaris univalens. In addition, we carried out in-depth analyses of DNA elimination in the parasitic nematode of humans, Ascaris lumbricoides, and the parasitic nematode of dogs, Toxocara canis. Our analysis of nematode DNA elimination reveals that in all species, repetitive sequences (that differ among the genera) and germline-expressed genes (approximately 1000-2000 or 5%-10% of the genes) are eliminated. Thirty-five percent of these eliminated genes are conserved among these nematodes, defining a core set of eliminated genes that are preferentially expressed during spermatogenesis. Our analysis supports the view that DNA elimination in nematodes silences germline-expressed genes. Over half of the chromosome break sites are conserved between Ascaris and Parascaris, whereas only 10% are conserved in the more divergent T. canis. Analysis of the chromosomal breakage regions suggests a sequence-independent mechanism for DNA breakage followed by telomere healing, with the formation of more accessible chromatin in the break regions prior to DNA elimination. Our genome assemblies and annotations also provide comprehensive resources for analysis of DNA elimination, parasitology research, and comparative nematode genome and epigenome studies.

On cherry and pitchfork distributions of random rooted and unrooted phylogenetic trees.

Tree shape statistics are important for investigating evolutionary mechanisms mediating phylogenetic trees. As a step towards bridging shape statistics between rooted and unrooted trees, we present a comparison study on two subtree statistics known as numbers of cherries and pitchforks for the proportional to distinguishable arrangements (PDA) and the Yule-Harding-Kingman (YHK) models. Based on recursive formulas on the joint distribution of the number of cherries and that of pitchforks, it is shown that cherry distributions are log-concave for both rooted and unrooted trees under these two models. Furthermore, the mean number of cherries and that of pitchforks for unrooted trees converge respectively to those for rooted trees under the YHK model while there exists a limiting gap of 1∕4 for the PDA model. Finally, the total variation distances between the cherry distributions of rooted and those of unrooted trees converge for both models. Our results indicate that caution is required for conducting statistical analysis for tree shapes involving both rooted and unrooted trees.

Integrative approach identifies corticosteroid response variant in diverse populations with asthma.

BACKGROUND: Although inhaled corticosteroid (ICS) medication is considered the cornerstone treatment for patients with persistent asthma, few ICS pharmacogenomic studies have involved nonwhite populations. OBJECTIVE: We sought to identify genetic predictors of ICS response in multiple population groups with asthma. METHODS: The discovery group comprised African American participants from the Study of Asthma Phenotypes and Pharmacogenomic Interactions by Race-Ethnicity (SAPPHIRE) who underwent 6 weeks of monitored ICS therapy (n = 244). A genome-wide scan was performed to identify single nucleotide polymorphism (SNP) variants jointly associated (ie, the combined effect of the SNP and SNP × ICS treatment interaction) with changes in asthma control. Top associations were validated by assessing the joint association with asthma exacerbations in 3 additional groups: African Americans (n = 803 and n = 563) and Latinos (n = 1461). RNA sequencing data from 408 asthmatic patients and 405 control subjects were used to examine whether genotype was associated with gene expression. RESULTS: One variant, rs3827907, was significantly associated with ICS-mediated changes in asthma control in the discovery set (P = 7.79 × 10-8) and was jointly associated with asthma exacerbations in 3 validation cohorts (P = .023, P = .029, and P = .041). RNA sequencing analysis found the rs3827907 C-allele to be associated with lower RNASE2 expression (P = 6.10 × 10-4). RNASE2 encodes eosinophil-derived neurotoxin, and the rs3827907 C-allele appeared to particularly influence ICS treatment response in the presence of eosinophilic inflammation (ie, high pretreatment eosinophil-derived neurotoxin levels or blood eosinophil counts). CONCLUSION: We identified a variant, rs3827907, that appears to influence response to ICS treatment in multiple population groups and likely mediates its effect through eosinophils.

Evaluating the quality of the 1000 genomes project data.

BACKGROUND: Data from the 1000 Genomes project is quite often used as a reference for human genomic analysis. However, its accuracy needs to be assessed to understand the quality of predictions made using this reference. We present here an assessment of the genotyping, phasing, and imputation accuracy data in the 1000 Genomes project. We compare the phased haplotype calls from the 1000 Genomes project to experimentally phased haplotypes for 28 of the same individuals sequenced using the 10X Genomics platform. RESULTS: We observe that phasing and imputation for rare variants are unreliable, which likely reflects the limited sample size of the 1000 Genomes project data. Further, it appears that using a population specific reference panel does not improve the accuracy of imputation over using the entire 1000 Genomes data set as a reference panel. We also note that the error rates and trends depend on the choice of definition of error, and hence any error reporting needs to take these definitions into account. CONCLUSIONS: The quality of the 1000 Genomes data needs to be considered while using this database for further studies. This work presents an analysis that can be used for these assessments.

A hybrid approach for de novo human genome sequence assembly and phasing.

Despite tremendous progress in genome sequencing, the basic goal of producing a phased (haplotype-resolved) genome sequence with end-to-end contiguity for each chromosome at reasonable cost and effort is still unrealized. In this study, we describe an approach to performing de novo genome assembly and experimental phasing by integrating the data from Illumina short-read sequencing, 10X Genomics linked-read sequencing, and BioNano Genomics genome mapping to yield a high-quality, phased, de novo assembled human genome.

Whole-Genome Sequencing of Pharmacogenetic Drug Response in Racially Diverse Children with Asthma.

RATIONALE: Albuterol, a bronchodilator medication, is the first-line therapy for asthma worldwide. There are significant racial/ethnic differences in albuterol drug response. OBJECTIVES: To identify genetic variants important for bronchodilator drug response (BDR) in racially diverse children. METHODS: We performed the first whole-genome sequencing pharmacogenetics study from 1,441 children with asthma from the tails of the BDR distribution to identify genetic association with BDR. MEASUREMENTS AND MAIN RESULTS: We identified population-specific and shared genetic variants associated with BDR, including genome-wide significant (P < 3.53 × 10-7) and suggestive (P < 7.06 × 10-6) loci near genes previously associated with lung capacity (DNAH5), immunity (NFKB1 and PLCB1), and ß-adrenergic signaling (ADAMTS3 and COX18). Functional analyses of the BDR-associated SNP in NFKB1 revealed potential regulatory function in bronchial smooth muscle cells. The SNP is also an expression quantitative trait locus for a neighboring gene, SLC39A8. The lack of other asthma study populations with BDR and whole-genome sequencing data on minority children makes it impossible to perform replication of our rare variant associations. Minority underrepresentation also poses significant challenges to identify age-matched and population-matched cohorts of sufficient sample size for replication of our common variant findings. CONCLUSIONS: The lack of minority data, despite a collaboration of eight universities and 13 individual laboratories, highlights the urgent need for a dedicated national effort to prioritize diversity in research. Our study expands the understanding of pharmacogenetic analyses in racially/ethnically diverse populations and advances the foundation for precision medicine in at-risk and understudied minority populations.

High-throughput single-molecule mapping links subtelomeric variants and long-range haplotypes with specific telomeres.

Accurate maps and DNA sequences for human subtelomere regions, along with detailed knowledge of subtelomere variation and long-range telomere-terminal haplotypes in individuals, are critical for understanding telomere function and its roles in human biology. Here, we use a highly automated whole genome mapping technology in nano-channel arrays to analyze large terminal human chromosome segments extending from chromosome-specific subtelomere sequences through subtelomeric repeat regions to terminal (TTAGGG)n repeat tracts. We establish detailed maps for subtelomere gap regions in the human reference sequence, detect many new large subtelomeric variants and demonstrate the feasibility of long-range haplotyping through segmentally duplicated subtelomere regions. These features make the method a uniquely valuable new tool for improving the quality of genome assemblies in complex DNA regions. Based on single molecule mapping of telomere-terminal DNA fragments, we provide proof of principle for a novel method to estimate telomere lengths linked to distinguishable telomeric haplotypes; this single-telomere genotyping method may ultimately enable delineation of human cis elements involved in telomere length regulation.