Pima County COVID-19 vaccine solutions dashboard project: lessons learned

Recent improvements in the accessibility of mapping tools and an increased recognition of the importance of leveraging data to inform public health operations has led to enthusiasm among public health departments to rapidly evolve their ability to analyze and apply data to programs. As the COVID-19 pandemic made evident, many health department data systems have been neglected for decades and data literacy among staff low. Significant federal dollars have been allocated to local health departments to modernize health systems. This case study recounts the effort to equip the Pima County Health Department with a highly sophisticated "COVID-19 Vaccines Solutions Dashboard" in 2021-2022, quantifying community vulnerability in the midst of the COVID-19 pandemic and shares key successes and challenges in process and outcomes that can guide other such dashboard initiatives. The experience informed the development of Pima' County Health Department's Data & Informatics Team as well as efforts to cultivate a more robust data culture throughout the department. Many health departments around the United States are in a similar position, and these lessons learned are widely applicable.

ICF1-Syndrome-Associated DNMT3B Mutations Prevent De Novo Methylation at a Subset of Imprinted Loci during iPSC Reprogramming

Parent-of-origin-dependent gene expression of a few hundred human genes is achieved by differential DNA methylation of both parental alleles. This imprinting is required for normal development, and defects in this process lead to human disease. Induced pluripotent stem cells (iPSCs) serve as a valuable tool for in vitro disease modeling. However, a wave of de novo DNA methylation during reprogramming of iPSCs affects DNA methylation, thus limiting their use. The DNA methyltransferase 3B (DNMT3B) gene is highly expressed in human iPSCs; however, whether the hypermethylation of imprinted loci depends on DNMT3B activity has been poorly investigated. To explore the role of DNMT3B in mediating de novo DNA methylation at imprinted DMRs, we utilized iPSCs generated from patients with immunodeficiency, centromeric instability, facial anomalies type I (ICF1) syndrome that harbor biallelic hypomorphic DNMT3B mutations. Using a whole-genome array-based approach, we observed a gain of methylation at several imprinted loci in control iPSCs but not in ICF1 iPSCs compared to their parental fibroblasts. Moreover, in corrected ICF1 iPSCs, which restore DNMT3B enzymatic activity, imprinted DMRs did not acquire control DNA methylation levels, in contrast to the majority of the hypomethylated CpGs in the genome that were rescued in the corrected iPSC clones. Overall, our study indicates that DNMT3B is responsible for de novo methylation of a subset of imprinted DMRs during iPSC reprogramming and suggests that imprinting is unstable during a specific time window of this process, after which the epigenetic state at these regions becomes resistant to perturbation.

Proceedings from the Melanoma Research Foundation Mucosal Melanoma Meeting (December 16, 2022, New York, USA)

Mucosal melanoma remains a rare cancer with high mortality and a paucity of therapeutic options. This is due in significant part to its low incidence leading to limited patient access to expert care and downstream clinical/basic science data for research interrogation. Clinical challenges such as delayed and at times inaccurate diagnoses, and lack of consensus tumor staging have added to the suboptimal outcomes for these patients. Clinical trials, while promising, have been difficult to activate and accrue. While individual institutions and investigators have attempted to seek solutions to such problems, international, national, and local partnership may provide the keys to more efficient and innovative paths forward. Furthermore, a mucosal melanoma coalition would provide a potential network for patients and caregivers to seek expert opinion and advice. The Melanoma Research Foundation Mucosal Melanoma Meeting (December 16, 2022, New York, USA) highlighted the current clinical challenges faced by patients, providers, and scientists, identified current and future clinical trial investigations in this rare disease space, and aimed to increase national and international collaboration among the mucosal melanoma community in an effort to improve patient outcomes. The included proceedings highlight the clinical challenges of mucosal melanoma, global clinical trial experience, basic science advances in mucosal melanoma, and future directions, including the creation of shared rare tumor registries and enhanced collaborations.

The aberrant epigenome of DNMT3B-mutated ICF1 patient iPSCs is amenable to correction, with the exception of a subset of regions with H3K4me3- and/or CTCF-based epigenetic memory

Bi-allelic hypomorphic mutations in DNMT3B disrupt DNA methyltransferase activity and lead to immunodeficiency, centromeric instability, facial anomalies syndrome, type 1 (ICF1). Although several ICF1 phenotypes have been linked to abnormally hypomethylated repetitive regions, the unique genomic regions responsible for the remaining disease phenotypes remain largely uncharacterized. Here we explored two ICF1 patient-derived induced pluripotent stem cells (iPSCs) and their CRISPR-Cas9-corrected clones to determine whether DNMT3B correction can globally overcome DNA methylation defects and related changes in the epigenome. Hypomethylated regions throughout the genome are highly comparable between ICF1 iPSCs carrying different DNMT3B variants, and significantly overlap with those in ICF1 patient peripheral blood and lymphoblastoid cell lines. These regions include large CpG island domains, as well as promoters and enhancers of several lineage-specific genes, in particular immune-related, suggesting that they are premarked during early development. CRISPR-corrected ICF1 iPSCs reveal that the majority of phenotype-related hypomethylated regions reacquire normal DNA methylation levels following editing. However, at the most severely hypomethylated regions in ICF1 iPSCs, which also display the highest increases in H3K4me3 levels and/or abnormal CTCF binding, the epigenetic memory persists, and hypomethylation remains uncorrected. Overall, we demonstrate that restoring the catalytic activity of DNMT3B can reverse the majority of the aberrant ICF1 epigenome. However, a small fraction of the genome is resilient to this rescue, highlighting the challenge of reverting disease states that are due to genome-wide epigenetic perturbations. Uncovering the basis for the persistent epigenetic memory will promote the development of strategies to overcome this obstacle.

Syllabi collection on diversity and intersectionality in public health: reflecting on the development

Background

Highlighting the intersectionalities between different markers of diversity and health inequities encourages the reconsideration of normativities in public health (PH). We developed an open access collection of syllabi on the relevance of intersectionality and diversity in PH together with the Association of Schools of Public Health in the European Region (ASPHER).

Objectives

We developed the syllabi in a participatory, iterative process guided by transformative teaching pedagogy. We reflect on this process and how this can inform the enhancement of the syllabi themselves, as well as future curriculum development.

Results

We recruited a core group of 9 PH researchers, teachers and professionals from all career levels from participants of introductory session presentations in different settings (e.g., 14th EPHC, ASPHER Retreat). The core group met once a month for one year online, and each meeting took the form of co-working sessions in breakout rooms to develop the syllabi based on interest and expertise. We designed a qualitative online survey to evaluate and ensure the scientific rigor and pedagogical value of the syllabi. We invited critical and constructive input from ASPHER member school professionals with expertise in intersectionality, diversity or curriculum development in PH in terms of content and pedagogy.

Conclusions

Drawing from the expertise of the PH community we combined diverse professional and cultural backgrounds, experiences from different career levels and PH education systems, as well as specialisation in the PH field. The transformative pedagogical approach was considered particularly valuable in strengthening competences such as reflexive strategies and self-, social- and global awareness which are key to teaching on diversity and intersectionality issues. The peer-review structure supports the uptake in PH education and a sustainable implementation. The collection will also allow PH faculty to diversify their pedagogical approaches.

Key messages

• Inclusion of health inequities, diversity and social injustice issues is crucial in public health curricula, since an intersectional perspective is increasingly acknowledged in public health research.

• The syllabi collection will equip public health teachers of all career levels to develop their own course material on social identities and their significance for public health.

MBTPS1 regulates proliferation of colorectal cancer primarily through its action on sterol regulatory element-binding proteins

Among the main metabolic pathways implicated in cancer cell proliferation are those of cholesterol and fatty acid synthesis, both of which are tightly regulated by sterol regulatory element-binding proteins (SREBPs). SREBPs are activated through specific cleavage by membrane-bound transcription factor protease 1 (MBTPS1), a serine protease that cleaves additional substrates (ATF6, BDNF, CREBs and somatostatin), some of which are also implicated in cell proliferation. The goal of this study was to determine whether MBTPS1 may serve as a master regulator in proliferation of colorectal cancer (CRC). Tumors from CRC patients showed variable levels of MBTPS1 mRNA, which were in positive correlation with the levels of SREBPs and ATF6, and in reverse correlation with BDNF levels. Chemical inhibition of MBTPS1 activity in two CRC-derived cell lines resulted in a marked decrease in the levels of SREBPs, but not of its other substrates and a marked decrease in cell proliferation, which suggested that MBTPS1 activity is critical for proliferation of these cells. In accordance, CRISPR/Cas9 targeted knockout (KO) of the MBTPS1 gene resulted in the survival of only a single clone that presented a phenotype of severely attenuated proliferation and marked downregulation of several energy metabolism pathways. We further showed that survival of the MBTPS1 KO clone was dependent upon significant upregulation of the type-1 interferon pathway, the inhibition of which halted proliferation entirely. Finally, rescue of the MBTPS1 KO cells, resulted in partial restoration of MBTPS1 levels, which was in accordance with partial recovery in proliferation and in SREBP levels. These finding suggest that MBTPS1 plays a critical role in regulating colon cancer proliferation primarily through SREBP-associated lipid metabolism, and as such may serve as a possible therapeutic target in CRC.

The drinking water crises of Flint and Havelock North: a failure of public health risk management

Between 2014 and 2016, there were two severe community water system (CWS) failures in Flint, Michigan (MI), USA and Havelock North, Hawkes Bay, New Zealand. These events had profound implications for public health in their respective countries. While the nature of both crises was different, certain aspects of the failings were strikingly similar. These included: failure of authorities to protect the integrity of their source water, 'wait-and-see approach' to address problems if and when they occurred, negligent approach to regulatory oversight and responsibility, substandard facilities and lack of knowledge and training of staff, failure of consultants and advisory services engaged by suppliers, and failure of government agencies to enforce regulations. The lessons from both incidents must be learned, or similar tragic events are likely to reoccur. The six principles identified in the Government Inquiry into the Havelock North outbreak are an essential first step. The next step is to implement them throughout the drinking water sector.

An introductory course on social identities and their importance in public health

Background

Social identities - e.g., sex/gender, ethnicity, ability, sexual orientation - and their intersections shape health inequalities in societies. Yet, a systematic, critical integration into public health curricula is lacking, especially in the European region. To address this gap, we developed a curriculum on social identities and their importance in public health in collaboration with ASPHER.

Objectives

The curriculum enables students to identify mechanisms of privilege and oppression related to social identities, and to learn how to determine biases within public health structures (and oneself). Moreover, it equips them with tools and skills to address and change biases in their practices to ultimately reduce health inequities.

Results

We conceptualized the curriculum in an iterative and participatory process in a group of students, young professionals and senior researchers from different countries in Western Europe and North America. The curriculum covers three core elements: 1) the introduction of concepts and terminology on diversity, equity and social identities in relation to health inequalities, 2) the reflection on the role of public health professionals and their responsibility within this system; and 3) spotlights on specific social identities, e.g., sex/gender or social class. In addition, it provides guidance on teaching methods to empower a broad range of public health professionals to engage with the course materials more easily.

Conclusions

The curriculum has the potential to strengthen the capacities of future public health professionals to acknowledge the relevance of social identities and how to respond effectively to contribute to health equity. After piloting and revisions, the course will be made available on an open access platform.

RBL2 bi-allelic truncating variants cause severe motor and cognitive impairment without evidence for abnormalities in DNA methylation or telomeric function

RBL2/p130, a member of the retinoblastoma family of proteins, is a key regulator of cell division and propagates irreversible senescence. RBL2/p130 is also involved in neuronal differentiation and survival, and eliminating Rbl2 in certain mouse strains leads to embryonic lethality accompanied by an abnormal central nervous system (CNS) phenotype. Conflicting reports exist regarding a role of RBL2/p130 in transcriptional regulation of DNA methyltransferases (DNMTs), as well as the control of telomere length. Here we describe the phenotype of three patients carrying bi-allelic RBL2-truncating variants. All presented with infantile hypotonia, severe developmental delay and microcephaly. Malignancies were not reported in carriers or patients. Previous studies carried out on mice and human cultured cells, associated RBL2 loss to DNA methylation and telomere length dysregulation. Here, we investigated whether patient cells lacking RBL2 display related abnormalities. The study of primary patient fibroblasts did not detect abnormalities in expression of DNMTs. Furthermore, methylation levels of whole genome DNA, and specifically of pericentromeric repeats and subtelomeric regions, were unperturbed. RBL2-null fibroblasts show no evidence for abnormal elongation by telomeric recombination. Finally, gradual telomere shortening, and normal onset of senescence were observed following continuous culturing of RBL2-mutated fibroblasts. Thus, this study resolves uncertainties regarding a potential non-redundant role for RBL2 in DNA methylation and telomere length regulation, and indicates that loss of function variants in RBL2 cause a severe autosomal recessive neurodevelopmental disorder in humans.

Epigenetic Characteristics of Human Subtelomeres Vary in Cells Utilizing the Alternative Lengthening of Telomeres (ALT) Pathway

Most human cancers circumvent senescence by activating a telomere length maintenance mechanism, most commonly involving telomerase activation. A minority of cancers utilize the recombination-based alternative lengthening of telomeres (ALT) pathway. The exact requirements for unleashing normally repressed recombination at telomeres are yet unclear. Epigenetic modifications at telomeric regions were suggested to be pivotal for activating ALT; however, conflicting data exist regarding their exact nature and necessity. To uncover common ALT-positive epigenetic characteristics, we performed a comprehensive analysis of subtelomeric DNA methylation, histone modifications, and TERRA expression in several ALT-positive and ALT-negative cell lines. We found that subtelomeric DNA methylation does not differentiate between the ALT-positive and ALT-negative groups, and most of the analyzed subtelomeres within each group do not share common DNA methylation patterns. Additionally, similar TERRA levels were measured in the ALT-positive and ALT-negative groups, and TERRA levels varied significantly among the members of the ALT-positive group. Subtelomeric H3K4 and H3K9 trimethylation also differed significantly between samples in the ALT-positive group. Our findings do not support a common route by which epigenetic modifications activate telomeric recombination in ALT-positive cells, and thus, different therapeutic approaches will be necessary to overcome ALT-dependent cellular immortalization.

Regulation of telomeric function by DNA methylation differs between humans and mice

The most distal 2 kb region in the majority of human subtelomeres contains CpG-rich promoters for TERRA, a long non-coding RNA. When the function of the de novo DNA methyltransferase DNMT3B is disrupted, as in ICF1 syndrome, subtelomeres are abnormally hypomethylated, subtelomeric heterochromatin acquires open chromatin characteristics, TERRA is highly expressed, and telomeres shorten rapidly. In this study, we explored whether the regulation of subtelomeric epigenetic characteristics by DNMT3B is conserved between humans and mice. Studying the DNA sequence of the distal 30 kb of the majority of murine q-arm subtelomeres indicated that these regions are relatively CpG-poor and do not contain TERRA promoters similar to those present in humans. Despite the lack of human-like TERRA promoters, we clearly detected TERRA expression originating from at least seven q-arm subtelomeres, and at higher levels in mouse pluripotent stem cells in comparison with mouse embryonic fibroblasts (MEFs). However, these differences in TERRA expression could not be explained by differential methylation of CpG islands present in the TERRA-expressing murine subtelomeres. To determine whether Dnmt3b regulates the expression of TERRA in mice, we characterized subtelomeric methylation and associated telomeric functions in cells derived from ICF1 model mice. Littermate-derived WT and ICF1 MEFs demonstrated no significant differences in subtelomeric DNA methylation, chromatin modifications, TERRA expression levels, telomere sister chromatid exchange or telomere length. We conclude that the epigenetic characteristics of murine subtelomeres differ substantially from their human counterparts and that TERRA transcription in mice is regulated by factors others than Dnmt3b.

Persistent epigenetic memory impedes rescue of the telomeric phenotype in human ICF iPSCs following DNMT3B correction

DNA methyltransferase 3B (DNMT3B) is the major DNMT that methylates mammalian genomes during early development. Mutations in human DNMT3B disrupt genome-wide DNA methylation patterns and result in ICF syndrome type 1 (ICF1). To study whether normal DNA methylation patterns may be restored in ICF1 cells, we corrected DNMT3B mutations in induced pluripotent stem cells from ICF1 patients. Focusing on repetitive regions, we show that in contrast to pericentromeric repeats, which reacquire normal methylation, the majority of subtelomeres acquire only partial DNA methylation and, accordingly, the ICF1 telomeric phenotype persists. Subtelomeres resistant to de novo methylation were characterized by abnormally high H3K4 trimethylation (H3K4me3), and short-term reduction of H3K4me3 by pharmacological intervention partially restored subtelomeric DNA methylation. These findings demonstrate that the abnormal epigenetic landscape established in ICF1 cells restricts the recruitment of DNMT3B, and suggest that rescue of epigenetic diseases with genome-wide disruptions will demand further manipulation beyond mutation correction.

Subtelomeric methylation distinguishes between subtypes of Immunodeficiency, Centromeric instability and Facial anomalies syndrome

Human telomeres and adjacent subtelomeres are packaged as heterochromatin. Subtelomeric DNA undergoes methylation during development by DNA methyltransferase 3B (DNMT3B), including the CpG-rich promoters of the long non-coding RNA (TERRA) embedded in these regions. The factors that direct DNMT3B methylation to human subtelomeres and maintain this methylation throughout lifetime are yet unknown. The importance of subtelomeric methylation is manifested through the abnormal telomeric phenotype in Immunodeficiency, Centromeric instability and Facial anomalies (ICF) syndrome type 1 patients carrying mutations in DNMT3B. Patient cells demonstrate subtelomeric hypomethylation, accompanied by elevated TERRA transcription, accelerated telomere shortening and premature senescence of fibroblasts. ICF syndrome can arise due to mutations in at least three additional genes, ZBTB24 (ICF2), CDCA7 (ICF3) and HELLS (ICF4). While pericentromeric repeat hypomethylation is evident in all ICF syndrome subtypes, the status of subtelomeric DNA methylation had not been described for patients of subtypes 2-4. Here we explored the telomeric phenotype in cells derived from ICF2-4 patients with the aim to determine whether ZBTB24, CDCA7 and HELLS also play a role in establishing and/or maintaining human subtelomeric methylation. We found normal subtelomeric methylation in ICF2-4 and accordingly low TERRA levels and unperturbed telomere length. Moreover, depleting the ICF2-4-related proteins in normal fibroblasts did not influence subtelomeric methylation. Thus, these gene products are not involved in establishing or maintaining subtelomeric methylation. Our findings indicate that human subtelomeric heterochromatin has specialized methylation regulation and highlight the telomeric phenotype as a characteristic that distinguishes ICF1 from ICF2-4.

DNA:RNA hybrids at telomeres - when it is better to be out of the (R) loop

R-loops (RLs) are three-stranded nucleic acid structures that contain a DNA:RNA hybrid and a displaced DNA strand. Genomic regions with GC skew and a G-rich transcript are particularly prone to form RLs. RLs play important physiological roles in cells; however, when present at abnormally high levels, they may threaten genome stability. The perfect GC skew of telomeric repeats and the discovery of telomeric repeat-containing RNA (TERRA), a long noncoding transcript that consists of the G-rich telomeric sequence, make telomeric sequences the perfect candidates for generating RLs. Indeed, in the past 5 years, telomere R-loops (TRLs) have been demonstrated in Saccharomyces cerevisiae, Trypanosoma brucei, and human cells. The presence of TRLs in normal human cells that transcribe low levels of TERRA, suggests a physiological role for these nucleic structures in telomere maintenance. Abnormally enhanced TERRA transcription, as found in several human pathological conditions, leads to high TRL levels and various cellular outcomes, depending on the recombinogenic capabilities of the cells. Study of TRLs in various organisms highlights the necessity for tight regulation of these structures, which can switch from beneficial to detrimental under different conditions. Here, we review the current state of knowledge on TRLs, describe several means by which TRLs are regulated, and discuss how findings from yeast are relevant to human pathological scenarios in which TRLs are deregulated.

No Equity, No Triple Aim: Strategic Proposals to Advance Health Equity in a Volatile Policy Environment

Health professionals, including social workers, community health workers, public health workers, and licensed health care providers, share common interests and responsibilities in promoting health equity and improving social determinants of health-the conditions in which people live, work, play, and learn. We summarize the underlying causes of health inequity and comparatively poor health outcomes in the United States. We describe barriers to realizing the hope embedded in the 2010 Patient Protection and Affordable Care Act, that moving away from fee-for-service payments will naturally drive care upstream as providers respond to greater financial risk by undertaking greater prevention efforts for the health of their patients. We assert that health equity should serve as the guiding framework for achieving the Triple Aim of health care reform and outline practical opportunities for improving care and promoting stronger efforts to address social determinants of health. These proposals include developing a dashboard of measures to assist providers committed to health equity and community-based prevention and to promote institutional accountability for addressing socioeconomic factors that influence health.

Non-random length distribution of individual telomeres in immunodeficiency, centromeric instability and facial anomalies syndrome, type I

Mutations in the de novo DNA methyltransferase DNMT3B lead to Immunodeficiency, Centromeric Instability and Facial anomalies (ICF) syndrome, type I. This syndrome is characterized, among other hypomethylated genomic loci, by severe subtelomeric hypomethylation that is associated with abnormally short telomere length. While it was demonstrated that the mean telomere length is significantly shorter in ICF type I cells, it is unknown whether all telomeres are equally vulnerable to shortening. To study this question we determined by combined telomere-FISH and spectral karyotyping the relative length of each individual telomere in lymphoblastoid cell lines (LCLs) generated from multiple ICF syndrome patients and control individuals. Here we confirm the short telomere lengths, and demonstrate that telomere length variance in the ICF patient group is much larger than in the control group, suggesting that not all telomeres shorten in a uniform manner. We identified a subgroup of telomeres whose relatively short lengths can distinguish with a high degree of certainty between a control and an ICF metaphase, proposing that in ICF syndrome cells, certain individual telomeres are consistently at greater risk to shorten than others. The majority of these telomeres display high sequence identity at the distal 2 kb of their subtelomeres, suggesting that the attenuation in DNMT3B methylation capacity affects individual telomeres to different degrees based, at least in part, on the adjacent subtelomeric sequence composition.

Telomeres in ICF syndrome cells are vulnerable to DNA damage due to elevated DNA:RNA hybrids

DNA:RNA hybrids, nucleic acid structures with diverse physiological functions, can disrupt genome integrity when dysregulated. Human telomeres were shown to form hybrids with the lncRNA TERRA, yet the formation and distribution of these hybrids among telomeres, their regulation and their cellular effects remain elusive. Here we predict and confirm in several human cell types that DNA:RNA hybrids form at many subtelomeric and telomeric regions. We demonstrate that ICF syndrome cells, which exhibit short telomeres and elevated TERRA levels, are enriched for hybrids at telomeric regions throughout the cell cycle. Telomeric hybrids are associated with high levels of DNA damage at chromosome ends in ICF cells, which are significantly reduced with overexpression of RNase H1. Our findings suggest that abnormally high TERRA levels in ICF syndrome lead to accumulation of telomeric hybrids that, in turn, can result in telomeric dysfunction.

ICF syndrome cells exhibit shortened telomeres and elevated levels of the noncoding RNA TERRA. Here the authors show this is associated with high levels of DNA damage, suggesting an increase in telomere dysfunction due to the formation of DNA: RNA hybrids

Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects

The analysis of individuals with telomere defects may shed light on the delicate interplay of factors controlling genome stability, premature aging, and cancer. We herein describe two Coats plus patients with telomere and genomic defects; both harbor distinct, novel mutations in STN1, a member of the human CTC1-STN1-TEN1 (CST) complex, thus linking this gene for the first time to a human telomeropathy. We characterized the patients' phenotype, recapitulated it in a zebrafish model and rescued cellular and clinical aspects by the ectopic expression of wild-type STN1 or by thalidomide treatment. Interestingly, a significant lengthy control of the gastrointestinal bleeding in one of our patients was achieved by thalidomide treatment, exemplifying a successful bed-to-bench-and-back approach.

Biology of advanced uveal melanoma and next steps for clinical therapeutics

Uveal melanoma is the most common intraocular malignancy although it is a rare subset of all melanomas. Uveal melanoma has distinct biology relative to cutaneous melanoma, with widely divergent patient outcomes. Patients diagnosed with a primary uveal melanoma can be stratified for risk of metastasis by cytogenetics or gene expression profiling, with approximately half of patients developing metastatic disease, predominately hepatic in location, over a 15-yr period. Historically, no systemic therapy has been associated with a clear clinical benefit for patients with advanced disease, and median survival remains poor. Here, as a joint effort between the Melanoma Research Foundation's ocular melanoma initiative, CURE OM and the National Cancer Institute, the current understanding of the molecular and immunobiology of uveal melanoma is reviewed, and on-going laboratory research into the disease is highlighted. Finally, recent investigations relevant to clinical management via targeted and immunotherapies are reviewed, and next steps in the development of clinical therapeutics are discussed.

Induced pluripotent stem cells as a model for telomeric abnormalities in ICF type I syndrome

Human telomeric regions are packaged as constitutive heterochromatin, characterized by extensive subtelomeric DNA methylation and specific histone modifications. ICF (immunodeficiency, centromeric instability, facial anomalies) type I patients carry mutations in DNA methyltransferase 3B (DNMT3B) that methylates de novo repetitive sequences during early embryonic development. ICF type I patient fibroblasts display hypomethylated subtelomeres, abnormally short telomeres and premature senescence. In order to study the molecular mechanism by which the failure to de novo methylate subtelomeres results in accelerated telomere shortening, we generated induced pluripotent stem cells (iPSCs) from 3 ICF type I patients. Telomeres were elongated in ICF-iPSCs during reprogramming, and the senescence phenotype was abolished despite sustained subtelomeric hypomethylation and high TERRA levels. Fibroblast-like cells (FLs) isolated from differentiated ICF-iPSCs maintained abnormally high TERRA levels, and telomeres in these cells shortened at an accelerated rate, leading to early senescence, thus recapitulating the telomeric phenotype of the parental fibroblasts. These findings demonstrate that the abnormal telomere phenotype associated with subtelomeric hypomethylation is overridden in cells expressing telomerase, therefore excluding telomerase inhibition by TERRA as a central mechanism responsible for telomere shortening in ICF syndrome. The data in the current study lend support to the use of ICF-iPSCs for modeling of phenotypic and molecular defects in ICF syndrome and for unraveling the mechanism whereby subtelomeric hypomethylation is linked to accelerated telomeric loss in this syndrome.

Characterization and rescue of telomeric abnormalities in ICF syndrome type I fibroblasts

Mutations in the human DNA methyltransferase 3B (DNMT3B) gene lead to ICF (immunodeficiency, centromeric region instability, and facial anomalies) syndrome type I. We have previously described a telomere-related phenotype in cells from these patients, involving severe hypomethylation of subtelomeric regions, abnormally short telomeres and high levels of telomeric-repeat-containing RNA (TERRA). Here we demonstrate that ICF-patient fibroblasts carry abnormally short telomeres at a low population doubling (PD) and enter senescence prematurely. Accordingly, we attempted to rescue the senescence phenotype by ectopic expression of human telomerase, which led to elongated telomeres with hypomethylated subtelomeres. The senescence phenotype was overcome under these conditions, thus dissociating subtelomeric-DNA hypomethylation per se from the senescence phenotype. In addition, we examined whether the subtelomeric methylation could be restored by expression of a normal copy of full length DNMT3B1 in ICF fibroblasts. Ectopic expression of DNMT3B1 failed to rescue the abnormal hypomethylation at subtelomeres. However, partial rescue of subtelomeric-hypomethylation was achieved by co-expression of DNMT3B1 together with DNA methyltransferase 3-like (DNMT3L), encoding a protein that functions as a stimulator of DNMT3A and DNMT3B. DNMT3B1 and DNMT3L are predominantly expressed during early embryonic development, suggesting that de novo subtelomeric DNA methylation during crucial stages of human embryonic development may be necessary for setting and maintaining normal telomere length.

Digital image analysis of cells stained with the senescence-associated β-galactosidase assay

Cellular senescence plays important roles in the aging process of complex organisms, in response to stress and in tumor suppression. Several markers can be used to identify senescent cells, of which the most widely used is the senescence-associated β-galactosidase (SABG) activity. Here we describe a procedure for digital image analysis of cells stained by the SABG staining technique at pH 6 or at pH 4. This analysis is highly reproducible and sensitive to subtle differences in staining intensities resulting from diverse cellular senescence pathways in culture.

The effect of acute exercise on undercarboxylated osteocalcin in obese men

SUMMARY

The purpose of this study was to examine if the reduction in glucose post-exercise is mediated by undercarboxylated osteocalcin (unOC). Obese men were randomly assigned to do aerobic or power exercises. The change in unOC levels was correlated with the change in glucose levels post-exercise. The reduction in glucose post-acute exercise may be partly related to increased unOC.

INTRODUCTION

Osteocalcin (OC) in its undercarboxylated (unOC) form may contribute to the regulation of glucose homeostasis. As exercise reduces serum glucose and improves insulin sensitivity in obese individuals and individuals with type 2 diabetes (T2DM), we hypothesised that this benefit was partly mediated by unOC.

METHODS

Twenty-eight middle-aged (52.4 ± 1.2 years, mean ± SEM), obese (BMI = 32.1 ± 0.9 kg m(-2)) men were randomly assigned to do either 45 min of aerobic (cycling at 75% of VO(2peak)) or power (leg press at 75% of one repetition maximum plus jumping sequence) exercises. Blood samples were taken at baseline and up to 2 h post-exercise.

RESULTS

At baseline, unOC was negatively correlated with glucose levels (r = -0.53, p = 0.003) and glycosylated haemoglobin (HbA1c) (r = -0.37, p = 0.035). Both aerobic and power exercises reduced serum glucose (from 7.4 ± 1.2 to 5.1 ± 0.5 mmol L(-1), p = 0.01 and 8.5 ± 1.2 to 6.0 ± 0.6 mmol L(-1), p = 0.01, respectively). Aerobic exercise significantly increased OC, unOC and high-molecular-weight adiponectin, while power exercise had a limited effect on OC and unOC. Overall, those with higher baseline glucose and HbA1c had greater reductions in glucose levels after exercise (r = -0.46, p = 0.013 and r = -0.43, p = 0.019, respectively). In a sub-group of obese people with T2DM, the percentage change in unOC levels was correlated with the percentage change in glucose levels post-exercise (r = -0.51, p = 0.038).

CONCLUSIONS

This study reports that the reduction in serum glucose post-acute exercise (especially aerobic exercise) may be partly related to increased unOC.

Oxygen (O2) kinetics during early recovery from peak exercise in patients with Type 2 diabetes

AIMS

To examine the oxygen (O(2)) kinetics during early recovery from peak exercise in patients with Type 2 diabetes and to examine whether oxygen O(2) recovery is associated with fasting glucose and HbA(1c) in this population.

METHODS

Eighty-nine participants (52 men) aged 51.8 ± 7.1 years (mean ± SD) were divided into three groups: normal weight (BMI ≤ 25.0 kg/m(2)), overweight/obese without diabetes (BMI ≥ 26 kg/m(2)) and overweight/obese with Type 2 diabetes. Participants were assessed for their aerobic power (VO(2peak)) on a cycle ergometer, provided a fasting blood sample and underwent a series of anthropometric measurements. Early recovery period was measured for 60 s from cessation of exercise and expressed as percentage of VO(2peak) (higher percentage represents slower recovery).

RESULTS

No significant differences were observed for age between the three study groups. Both the overweight/obese groups without diabetes and with Type 2 diabetes had higher BMI than the normal weight group, with no significant differences between overweight/obese participants without diabetes and those with diabetes. Participants with Type 2 diabetes had lower VO(2peak) than overweight/obese participants without diabetes and normal weight individuals (19.6 ± 4.8, 22.6 ± 5.4 and 25.7 ± 5.3 ml kg(-1) min(-1), respectively, P < 0.004 for overall trends). Participants with Type 2 diabetes also had slower recovery in oxygen O(2) kinetics after exercise, compared with both normal weight and overweight/obese individuals without diabetes (56.5 ± 7.7, 49.2 ± 7.2, 47.7 ± 7.4%, P < 0.004 for overall trends). Multiple regression analysis revealed that percentage of oxygen O(2) recovery was a stronger predictor than VO(2peak), BMI or age for fasting glucose and HbA(1c).

CONCLUSIONS

Patients with Type 2 diabetes have lower VO(2peak) and prolonged oxygen O(2) recovery from peak exercise. However, only prolonged oxygen O(2) recovery was associated with fasting glucose and HbA(1c).

Quantitative digital in situ senescence-associated β-galactosidase assay

BACKGROUND

Cellular senescence plays important roles in the aging process of complex organisms, in tumor suppression and in response to stress. Several markers can be used to identify senescent cells, of which the most widely used is the senescence-associated β-galactosidase (SABG) activity. The main advantage of SABG activity over other markers is the simplicity of the detection assay and the capacity to identify in situ a senescent cell in a heterogeneous cell population. Several approaches have been introduced to render the SABG assay quantitative. However none of these approaches to date has proven particularly amenable to quantitative analysis of SABG activity in situ. Furthermore the role of cellular senescence (CS) in vivo remains unclear mainly due to the ambiguity of current cellular markers in identifying CS of individual cells in tissues.

RESULTS

In the current study we applied a digital image analysis technique to the staining generated using the original SABG assay, and demonstrate that this analysis is highly reproducible and sensitive to subtle differences in staining intensities resulting from diverse cellular senescence pathways in culture. We have further validated our method on mouse kidney samples with and without diabetes mellitus, and show that a more accurate quantitative SABG activity with a wider range of values can be achieved at a pH lower than that used in the conventional SABG assay.

CONCLUSIONS

We conclude that quantitative in situ SABG assay, is feasible and reproducible and that the pH at which the reaction is performed should be tailored and chosen, depending on the research question and experimental system of interest.

Reprogramming of telomeric regions during the generation of human induced pluripotent stem cells and subsequent differentiation into fibroblast-like derivatives

Human induced pluripotent stem (hiPS) cells provide therapeutic promises, as well as a potent in vitro model for studying biological processes which take place during human embryonic development and subsequent differentiation in normal and disease states. The epigenetic characteristics of iPS cells are reprogrammed to the embryonic state at which they acquire pluripotency. In addition, telomeres in hiPS cell must elongate sufficiently to provide the necessary replicative potential. Recent studies have demonstrated that the epigenetic characteristics of telomeric and subtelomeric regions are pivotal in regulating telomere length. Here we study telomere length, subtelomeric DNA methylation and telomeric-repeat-containing RNA (TERRA) expression in several hiPS cell clones derived from normal neonatal foreskin fibroblasts. We find that telomeres lengthen significantly in hiPS cells in comparison to the parental fibroblast source, and progressively shorten after differentiation back into fibroblast-like cells, concomitantly with telomerase activation and down-regulation, respectively. Subtelomeres in hiPS cells were found to be generally hypermethylated in comparison to the parental source. However bisulfite analysis revealed that at several subtelomeres examined, methylation levels differed between hiPS clones and that both de novo methylation and demethylation processes occurred during telomere reprogramming. Notably, although subtelomeres were in general very highly methylated, TERRA levels were elevated in hiPS cells, albeit to different degrees in the various clones. TERRA elevation may reflect enhanced stability or impaired degradation in hiPS cells, and/or alternatively, increased transcription from the hypomethylated subtelomeres. We suggest that TERRA may play a role in regulation of appropriate telomere function and length in hiPS cells.

Altered chromosomal positioning, compaction, and gene expression with a lamin A/C gene mutation

BACKGROUND

Lamins A and C, encoded by the LMNA gene, are filamentous proteins that form the core scaffold of the nuclear lamina. Dominant LMNA gene mutations cause multiple human diseases including cardiac and skeletal myopathies. The nuclear lamina is thought to regulate gene expression by its direct interaction with chromatin. LMNA gene mutations may mediate disease by disrupting normal gene expression.

METHODS/FINDINGS

To investigate the hypothesis that mutant lamin A/C changes the lamina's ability to interact with chromatin, we studied gene misexpression resulting from the cardiomyopathic LMNA E161K mutation and correlated this with changes in chromosome positioning. We identified clusters of misexpressed genes and examined the nuclear positioning of two such genomic clusters, each harboring genes relevant to striated muscle disease including LMO7 and MBNL2. Both gene clusters were found to be more centrally positioned in LMNA-mutant nuclei. Additionally, these loci were less compacted. In LMNA mutant heart and fibroblasts, we found that chromosome 13 had a disproportionately high fraction of misexpressed genes. Using three-dimensional fluorescence in situ hybridization we found that the entire territory of chromosome 13 was displaced towards the center of the nucleus in LMNA mutant fibroblasts. Additional cardiomyopathic LMNA gene mutations were also shown to have abnormal positioning of chromosome 13, although in the opposite direction.

CONCLUSIONS

These data support a model in which LMNA mutations perturb the intranuclear positioning and compaction of chromosomal domains and provide a mechanism by which gene expression may be altered.

Missense mutations in the APOL1 gene are highly associated with end stage kidney disease risk previously attributed to the MYH9 gene

MYH9 has been proposed as a major genetic risk locus for a spectrum of nondiabetic end stage kidney disease (ESKD). We use recently released sequences from the 1000 Genomes Project to identify two western African-specific missense mutations (S342G and I384M) in the neighboring APOL1 gene, and demonstrate that these are more strongly associated with ESKD than previously reported MYH9 variants. The APOL1 gene product, apolipoprotein L-1, has been studied for its roles in trypanosomal lysis, autophagic cell death, lipid metabolism, as well as vascular and other biological activities. We also show that the distribution of these newly identified APOL1 risk variants in African populations is consistent with the pattern of African ancestry ESKD risk previously attributed to MYH9.

Mapping by admixture linkage disequilibrium (MALD) localized an interval on chromosome 22, in a region that includes the MYH9 gene, which was shown to contain African ancestry risk variants associated with certain forms of ESKD (Kao et al. 2008; Kopp et al. 2008). MYH9 encodes nonmuscle myosin heavy chain IIa, a major cytoskeletal nanomotor protein expressed in many cell types, including podocyte cells of the renal glomerulus. Moreover, 39 different coding region mutations in MYH9 have been identified in patients with a group of rare syndromes, collectively termed the Giant Platelet Syndromes, with clear autosomal dominant inheritance, and various clinical manifestations, sometimes also including glomerular pathology and chronic kidney disease (Kopp 2010; Sekine et al. 2010). Accordingly, MYH9 was further explored in these studies as the leading candidate gene responsible for the MALD signal. Dense mapping of MYH9 identified individual single nucleotide polymorphisms (SNPs) and sets of such SNPs grouped as haplotypes that were found to be highly associated with a large and important group of ESKD risk phenotypes, which as a consequence were designated as MYH9-associated nephropathies (Bostrom and Freedman 2010). These included HIV-associated nephropathy (HIVAN), primary nonmonogenic forms of focal segmental glomerulosclerosis, and hypertension affiliated chronic kidney disease not attributed to other etiologies (Bostrom and Freedman 2010). The MYH9 SNP and haplotype associations observed with these forms of ESKD yielded the largest odds ratios (OR) reported to date for the association of common variants with common disease risk (Winkler et al. 2010). Two specific MYH9 variants (rs5750250 of S-haplotype and rs11912763 of F-haplotype) were designated as most strongly predictive on the basis of Receiver Operating Characteristic analysis (Nelson et al. 2010). These MYH9 association studies were then also extended to earlier stage and related kidney disease phenotypes and to population groups with varying degrees of recent African ancestry admixture (Behar et al. 2010; Freedman et al. 2009a, b; Nelson et al. 2010), and led to the expectation of finding a functional African ancestry causative variant within MYH9. However, despite intensive efforts including re-sequencing of the MYH9 gene no suggested functional mutation has been identified (Nelson et al. 2010; Winkler et al. 2010). This led us to re-examine the interval surrounding MYH9 and to the detection of novel missense mutations with predicted functional effects in the neighboring APOL1 gene, which are significantly more associated with ESKD than all previously reported SNPs in MYH9.

A loss-of-function mutation in NaPi-IIa and renal Fanconi's syndrome

We describe two siblings from a consanguineous family with autosomal recessive Fanconi's syndrome and hypophosphatemic rickets. Genetic analysis revealed a homozygous in-frame duplication of 21 bp in SLC34A1, which encodes the renal sodium-inorganic phosphate cotransporter NaPi-IIa, as the causative mutation. Functional studies in Xenopus laevis oocytes and in opossum kidney cells indicated complete loss of function of the mutant NaPi-IIa, resulting from failure of the transporter to reach the plasma membrane. These findings show that disruption of the human NaPi-IIa profoundly impairs overall renal phosphate reabsorption and proximal-tubule function and provide evidence of the critical role of NaPi-IIa in human renal phosphate handling.

African ancestry allelic variation at the MYH9 gene contributes to increased susceptibility to non-diabetic end-stage kidney disease in Hispanic Americans

Recent studies identified MYH9 as a major susceptibility gene for common forms of non-diabetic end-stage kidney disease (ESKD). A set of African ancestry DNA sequence variants comprising the E-1 haplotype, was significantly associated with ESKD. In order to determine whether African ancestry variants are also associated with disease susceptibility in admixed populations with differing genomic backgrounds, we genotyped a total of 1425 African and Hispanic American subjects comprising dialysis patients with diabetic and non-diabetic ESKD and controls, using 42 single nucleotide polymorphisms (SNPs) within the MYH9 gene and 40 genome-wide and 38 chromosome 22 ancestry informative markers. Following ancestry correction, logistic regression demonstrated that three of the E-1 SNPs are also associated with non-diabetic ESKD in the new sample sets of both African and Hispanic Americans, with a stronger association in Hispanic Americans. We also identified MYH9 SNPs that are even more powerfully associated with the disease phenotype than the E-1 SNPs. These newly associated SNPs, could be divided into those comprising a haplotype termed S-1 whose association was significant under a recessive or additive inheritance mode (rs5750248, OR 4.21, P < 0.01, Hispanic Americans, recessive), and those comprising a haplotype termed F-1 whose association was significant under a dominant or additive inheritance mode (rs11912763, OR 4.59, P < 0.01, Hispanic Americans, dominant). These findings strengthen the contention that a sequence variant of MYH9, common in populations with varying degrees of African ancestry admixture, and in strong linkage disequilibrium with the associated SNPs and haplotypes reported herein, strongly predisposes to non-diabetic ESKD.

Allelic inactivation of rDNA loci

Human cells contain several hundred ribosomal genes (rDNA) that are clustered into nucleolar organizer regions (NORs) on the short arms of five different acrocentric chromosomes. Only approximately 50% of the gene copies are actually expressed in somatic cells. Here, we used a new cytological technique to demonstrate that rDNA is regulated allelically in a regional manner, with one parental copy of each NOR being repressed in any individual cell. This process is similar to that of X-chromosome inactivation in females. Early in development, one copy of each NOR becomes late-replicating, thus probably marking it for inactivation and subsequent targeted de novo methylation at rDNA promoter regions. Once established, this multichromosomal allelic pattern is then maintained clonally in somatic cells. This pathway may serve as an epigenetic mechanism for controlling the number of available rDNA copies during development.

Medication diaries do not improve outcomes with highly active antiretroviral therapy in Kenyan children: a randomized clinical trial

Background

As highly active antiretroviral therapy (HAART) becomes increasingly available to African children, it is important to evaluate simple and feasible methods of improving adherence in order to maximize benefits of therapy.

Methods

HIV-1-infected children initiating World Health Organization non-nucleoside reverse transcriptase-inhibitor-containing first-line HAART regimens were randomized to use medication diaries plus counselling, or counselling only (the control arm of the study). The diaries were completed daily by caregivers of children randomized to the diary and counselling arm for nine months. HIV-1 RNA, CD4+ T cell count, and z-scores for weight-for-age, height-for-age and weight-for-height were measured at a baseline and every three to six months. Self-reported adherence was assessed by questionnaires for nine months.

Results

Ninety HIV-1-infected children initiated HAART, and were followed for a median of 15 months (interquartile range: 2–21). Mean CD4 percentage was 17.2% in the diary arm versus 16.3% in the control arm at six months (p = 0.92), and 17.6% versus 18.9% at 15 months (p = 0.36). Virologic response with HIV-1 RNA of <100 copies/ml at nine months was similar between the two arms (50% for the diary arm and 36% for the control, p = 0.83). The weight-for-age, height-for-age and weight-for-height at three, nine and 15 months after HAART initiation were similar between arms. A trend towards lower self-reported adherence was observed in the diary versus the control arm (85% versus 92%, p = 0.08).

Conclusion

Medication diaries did not improve clinical and virologic response to HAART over a 15-month period. Children had good adherence and clinical response without additional interventions. This suggests that paediatric HAART with conventional counselling can be a successful approach. Further studies on targeted approaches for non-adherent children will be important.

Inflammation, hepatic enzymes and resistance training in individuals with metabolic risk factors

AIMS

Increases in inflammatory markers, hepatic enzymes and physical inactivity are associated with the development of the metabolic syndrome (MetS). We examined whether inflammatory markers and hepatic enzymes are correlated with traditional risk factors for MetS and studied the effects of resistance training (RT) on these emerging risk factors in individuals with a high number of metabolic risk factors (HiMF, 2.9 +/- 0.8) and those with a low number of metabolic risk factors (LoMF, 0.5 +/- 0.5).

METHODS

Twenty-eight men and 27 women aged 50.8 +/- 6.5 years (mean +/- sd) participated in the study. Participants were randomized to four groups, HiMF training (HiMFT), HiMF control (HiMFC), LoMF training (LoMFT) and LoMF control (LoMFC). Before and after 10 weeks of RT [3 days/week, seven exercises, three sets with intensity gradually increased from 40-50% of one repetition maximum (1RM) to 75-85% of 1RM], blood samples were obtained for the measurement of pro-inflammatory cytokines, C-reactive protein (CRP), gamma-glutamyltransferase (GGT) and alanine aminotransferase (ALT).

RESULTS

At baseline, HiMF had higher interleukin-6 (33.9%), CRP (57.1%), GGT (45.2%) and ALT (40.6%) levels, compared with LoMF (all P < 0.05). CRP, GGT and ALT correlated with the number of risk factors (r = 0.48, 0.51 and 0.57, respectively, all P < 0.01) and with other anthropometric and clinical measures (r range from 0.26 to 0.60, P < 0.05). RT did not significantly alter inflammatory markers or hepatic enzymes (all P > 0.05).

CONCLUSIONS

HiMF was associated with increased inflammatory markers and hepatic enzyme concentrations. RT did not reduce inflammatory markers and hepatic enzymes in individuals with HiMF.

Hypomethylation of subtelomeric regions in ICF syndrome is associated with abnormally short telomeres and enhanced transcription from telomeric regions

Telomeres and adjacent subtelomeric regions are packaged as heterochromatin in many organisms. The heterochromatic features include DNA methylation, histones H3-Lys9 (Lysine 9) and H4-Lys20 (Lysine 20) methylation and heterochromatin protein1 alpha binding. Subtelomeric DNA is hypomethylated in human sperm and ova, and these regions are subjected to de novo methylation during development. In mice this activity is carried out by DNA methyltransferase 3b (Dnmt3b). Mutations in DNMT3B in humans lead to the autosomal-recessive ICF (immunodeficiency, centromeric region instability, facial anomalies) syndrome. Here we show that, in addition to several satellite and non-satellite repeats, the subtelomeric regions in lymphoblastoid and fibroblast cells of ICF patients are also hypomethylated to similar levels as in sperm. Furthermore, the telomeres are abnormally short in both the telomerase-positive and -negative cells, and many chromosome ends lack detectable telomere fluorescence in situ hybridization signals from either one or both sister-chromatids. In contrast to Dnmt3a/b(-/-) mouse embryonic stem cells, increased telomere sister-chromatid exchange was not observed in ICF cells. Hypomethylation of subtelomeric regions was associated in the ICF cells with advanced telomere replication timing and elevated levels of transcripts emanating from telomeric regions, known as TERRA (telomeric-repeat-containing RNA) or TelRNA. The current findings provide a mechanistic explanation for the abnormal telomeric phenotype observed in ICF syndrome and highlights the link between TERRA/TelRNA and structural telomeric integrity.

Early response to highly active antiretroviral therapy in HIV-1-infected Kenyan children

OBJECTIVES

To describe the early response to World Health Organization (WHO)-recommended nonnucleoside reverse transcriptase inhibitor (NNRTI)-based first-line highly active antiretroviral therapy (HAART) in HIV-1-infected Kenyan children unexposed to nevirapine.

DESIGN

Observational prospective cohort.

METHODS

HIV-1 RNA level, CD4 lymphocyte count, weight for age z score, and height for age z score were measured before the initiation of HAART and every 3 to 6 months thereafter. Children received no nutritional supplements.

RESULTS

Sixty-seven HIV-1-infected children were followed for a median of 9 months between August 2004 and November 2005. Forty-seven (70%) used zidovudine, lamivudine (3TC), and an NNRTI (nevirapine or efavirenz), whereas 25% used stavudine (d4T), 3TC, and an NNRTI. Nevirapine was used as the NNRTI by 46 (69%) children, and individual antiretroviral drug formulations were used by 63 (94%), with only 4 (6%) using a fixed-dose combination of d4T, 3TC, and nevirapine (Triomune; Cipla, Mumbai, India). In 52 children, the median height for age z score and weight for age z score rose from -2.54 to -2.17 (P<0.001) and from -2.30 to -1.67 (P=0.001), respectively, after 6 months of HAART. Hospitalization rates were significantly reduced after 6 months of HAART (17% vs. 58%; P<0.001). The median absolute CD4 count increased from 326 to 536 cells/microL (P<0.001), the median CD4 lymphocyte percentage rose from 5.8% before treatment to 15.4% (P<0.001), and the median viral load fell from 5.9 to 2.2 log10 copies/mL after 6 months of HAART (P<0.001). Among 43 infants, 47% and 67% achieved viral suppression to less than 100 copies/mL and 400 copies/mL, respectively, after 6 months of HAART.

CONCLUSION

Good early clinical and virologic response to NNRTI-based HAART was observed in HIV-1-infected Kenyan children with advanced HIV-1 disease.

The association of DNA sequence variation at the MAOA genetic locus with quantitative behavioural traits in normal males

Monoamine oxidase A (MAOA) catalyses the oxidative deamination of biogenic amines including neurotransmitters, mainly norepinephrine and serotonin in the brain and peripheral tissues. A nonsense mutation in the gene was shown to be involved in a rare X-linked behavioural syndrome, which includes impaired impulse control, aggression and borderline mental retardation (Brunner syndrome). Several recent studies have shown the association of genetic variation of a VNTR in the gene promoter with various pathological behavioural traits. In the present study the association of MAOA genetic variation with a large set of quantitative behavioural traits in normal individuals has been examined. DNA samples from 421 unrelated males were genotyped for 14 SNPs and for the promoter VNTR at the MAOA locus. An additional 16 SNPs were genotyped at apparently neutral loci across the X chromosome to serve as a genomic control for possible false positive associations due to population structure. Behavioural traits were measured using the NEO psychometric questionnaire, which is based on a 5-axis model of personality, and consists of 30 different quantitative traits. There was a robust association of the A2 ("straightforwardness") facet with common allelic variants at the promoter VNTR. Most of the tested traits were not associated with the VNTR despite reasonable power, thus demonstrating that the VNTR influence on quantitative behavioural traits in normal males may be very specific. In contrast, several traits of the C ("conscientiousness") axis were associated with less common SNP-defined haplotypes. Hence, it appears that common genetic variation at the VNTR contributes to the behavioural attribute of "straightforwardness", while rare haplotypes defined by SNPs downstream of the transcription start site may contribute to "conscientiousness". This study is used to address the validation, interpretation and limitation of genetic association studies of quantitative behavioural traits.