Down syndrome: national conference on patient registries, research databases, and biobanks

A December 2010 meeting, "Down Syndrome: National Conference on Patient Registries, Research Databases, and Biobanks," was jointly sponsored by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) at the National Institutes of Health (NIH) in Bethesda, MD, and the Global Down Syndrome Foundation (GDSF)/Linda Crnic Institute for Down Syndrome based in Denver, CO. Approximately 70 attendees and organizers from various advocacy groups, federal agencies (Centers for Disease Control and Prevention, and various NIH Institutes, Centers, and Offices), members of industry, clinicians, and researchers from various academic institutions were greeted by Drs. Yvonne Maddox, Deputy Director of NICHD, and Edward McCabe, Executive Director of the Linda Crnic Institute for Down Syndrome. They charged the participants to focus on the separate issues of contact registries, research databases, and biobanks through both podium presentations and breakout session discussions. Among the breakout groups for each of the major sessions, participants were asked to generate responses to questions posed by the organizers concerning these three research resources as they related to Down syndrome and then to report back to the group at large with a summary of their discussions. This report represents a synthesis of the discussions and suggested approaches formulated by the group as a whole.

Pseudoxanthoma elasticum: progress in diagnostics and research towards treatment : Summary of the 2010 PXE International Research Meeting

Pseudoxanthoma elasticum (PXE), a prototypic heritable disorder with ectopic mineralization, manifests with characteristic skin findings, ocular involvement, and cardiovascular problems. The classic forms of PXE are due to loss-of-function mutations in the ABCC6 gene, which encodes ABCC6, a putative transmembrane efflux transporter expressed primarily in the liver. While considerable progress has recently been made in understanding the molecular genetics and pathomechanisms of PXE, no effective or specific treatment is currently available for this disorder. PXE International, the premiere patient advocacy organization, organized a workshop in November 2010 to assess the current state of diagnostics and research to develop an agenda towards treatment of PXE. This overview summarizes the progress in PXE research, with emphasis on molecular therapies for this, currently intractable, disorder.

Power to the people: participant ownership of clinical trial data

Participation in clinical trials is dismally low. In this age of electronic sharing of information of all sorts, trial participants can easily share clinical trial data. The benefits of participant ownership and sharing of trial data appear to outweigh the risks. Thus, the time has come to crowd-source data for diagnostic and therapy development.

A randomized controlled trial of oral phosphate binders in the treatment of pseudoxanthoma elasticum

BACKGROUND

Pseudoxanthoma elasticum (PXE) is a rare connective tissue disorder involving fragmentation and mineralization of elastic fibers predominantly in the skin, eyes, and cardiovascular system.

OBJECTIVE

The objective of this study was to assess the efficacy of sevelamer hydrochloride on the reversal of elastic fiber calcification and clinical lesions of PXE.

METHODS

This was a randomized, double-blind, placebo-controlled, two-part prospective study. In the first year, 40 patients with PXE were randomized to receive either sevelamer hydrochloride (800 mg by mouth three times daily) or placebo in a 1:1 ratio. In the second year, all patients received sevelamer hydrochloride (800 mg by mouth three times daily).

RESULTS

In the first year, the placebo and treatment groups' mean calcium scores decreased from 29.52 to 15.97 (41.93% mean improvement) and 27.48 to 16.75 (38.37% mean improvement), respectively. In the second year, the mean calcium scores decreased to 13.36 (53.94%) and 14.03 (51.35%) in these groups. The mean clinical score in the placebo group decreased from 6.25 to 6.05 at year 1 (2% improvement) whereas the mean clinical score in the sevelamer hydrochloride group decreased from 7.10 to 6.55 (7% improvement). In year 2, the scores in the original placebo and sevelamer hydrochloride groups decreased to 5.33 (14% improvement) and 5.72 (19% improvement), respectively.

LIMITATIONS

Magnesium stearate in our placebo and active drugs may have played a confounding role in this study, contributing to the small differences observed in these two groups.

CONCLUSION

Sevelamer hydrochloride produced a reduction in both calcification levels and clinical scores; however, this difference was not statistically significant compared with placebo. Future clinical studies should examine the inhibitory role and potential therapeutic effect of magnesium in PXE.

Acquired pseudoxanthoma elasticum presenting after liver transplantation

BACKGROUND

Pseudoxanthoma elasticum (PXE) is thought to be a metabolic disorder resulting from mutations in the gene encoding the cellular transporter, ABCC6, which is primarily expressed in liver and kidney. We encountered 3 patients who developed clinical and histopathological evidence of PXE after liver transplantation, suggesting that PXE could have been acquired from the transplanted organ.

OBJECTIVE

We sought to delineate the clinical features and screen each patient and samples of donor liver for mutations in the ABCC6 gene.

METHODS

Each patient underwent full clinical examination, skin biopsy, and ophthalmologic examination, and whole genome sequencing using standard techniques. Fixed samples of donor liver tissue were available for mutation analysis in two patients and of donor kidney tissue in one.

RESULTS

All 3 patients had unequivocal clinical and histopathologic evidence of PXE. No patient (or family member available for screening) had evidence of mutations in ABCC6. Neither liver specimen nor the single available kidney specimen showed evidence of mutations in ABCC6.

LIMITATIONS

Liver tissue was not available from one patient and DNA was of poor quality in another, resulting in limited screening. Genetic testing does not detect ABCC6 mutations in 10% of patients with confirmed PXE.

CONCLUSION

Although we were unable to demonstrate ABCC6 mutations in limited screening of fixed donor livers, the absence of any PXE mutations in the affected patients, the timing of onset of PXE, and the known acquisition of other metabolic disorders and coagulopathies from donor livers suggest that PXE was likely acquired via liver transplantation.

Genetic Alliance Registry and BioBank: a novel disease advocacy-driven research solution

The Genetic Alliance Registry and BioBank was founded in 2003 on the principal that a shared infrastructure would facilitate easy flow of resources and accelerate disease-specific research. Based on the Pseudoxanthoma Elasticum International Registry and BioBank, six disease advocacy organizations came together to identify the best solutions for advocacy organizations to promote and collect biological samples with associated clinical information from their members. This required a flexible system that could accommodate an extensive amount of data and samples, support new avenues of research, yet be adaptable to meet the needs of a variety of organizations, and straightforward to implement and use. After extensive landscape analyses, a cross-disease, infinitely expandable registry and biorepository was established. This article reports on this effort and shares the lessons learned.

How will GINA influence participation in pharmacogenomics research and clinical testing?

After a 13-year battle in Congress--longer than it took to map the human genome--the Genetic Information Nondiscrimination Act (GINA) was passed into law on 21 May 2008. Before its passing, Francis Collins, then director of the National Human Genome Research Institute, testified before the 110th Congress that the success of personalized medicine hinged on the passing of the legislation. How will GINA, which takes effect in 2009, influence participation in pharmacogenomic research and clinical testing?

Ensuring the safe use of genomic medicine in children

Several clinical guidelines recommend that genetic testing in children be limited to tests with immediate clinical benefit. However, use of genome risk profiling will not likely meet this requirement, as the benefits are anticipated to be years away. Children who are at higher risk, though, will benefit the most from early initiation of treatment or interventions. The shift in benefit from immediate to long-term benefit warrants a reevaluation of the current practices of testing in children. In this commentary, the authors advocate the use of genomic risk profiling to identify children at increased risk who would benefit from early intervention, but recognize that its integration in clinical practice for this population will require a more nuanced approach to delivery and follow-up. In particular, the importance of counseling, context, consent, communication, and follow-up in the delivery of genomic risk testing to children and adolescents is highlighted.

The Scientific Foundation for personal genomics: recommendations from a National Institutes of Health-Centers for Disease Control and Prevention multidisciplinary workshop

The increasing availability of personal genomic tests has led to discussions about the validity and utility of such tests and the balance of benefits and harms. A multidisciplinary workshop was convened by the National Institutes of Health and the Centers for Disease Control and Prevention to review the scientific foundation for using personal genomics in risk assessment and disease prevention and to develop recommendations for targeted research. The clinical validity and utility of personal genomics is a moving target with rapidly developing discoveries but little translation research to close the gap between discoveries and health impact. Workshop participants made recommendations in five domains: (1) developing and applying scientific standards for assessing personal genomic tests; (2) developing and applying a multidisciplinary research agenda, including observational studies and clinical trials to fill knowledge gaps in clinical validity and utility; (3) enhancing credible knowledge synthesis and information dissemination to clinicians and consumers; (4) linking scientific findings to evidence-based recommendations for use of personal genomics; and (5) assessing how the concept of personal utility can affect health benefits, costs, and risks by developing appropriate metrics for evaluation. To fulfill the promise of personal genomics, a rigorous multidisciplinary research agenda is needed.

What do leaders of disease-specific advocacy organizations know about pharmacogenomics and biomarkers, anyway?

Disease Advocacy Organizations (DAOs) make meaningful contributions to the development of tests and therapeutics across the development pipeline, from cohort development to actual drug discovery. The process of developing biomarkers and validating them is fraught with a high failure rate and enormous expense. DAOs can harness new information technologies to increase effectiveness, including systems to dynamically consent individuals to participate in registries and trials. These new technologies can alleviate some of the expense in biomarker development. Information aggregation with consumer control of information at its core will eventually permit a national surveillance system for pre- and post-treatment analysis. A stronger and more scientific basis on which to build quality control and assurance of biomarker determination is needed. Validation must be supported in the future, in the same manner discovery was in the past, including through federal funding and philanthropic giving. DAOs can accelerate the process of biomarker development by building robust, well-characterized cohorts.

Providers' knowledge of genetics: A survey of 5915 individuals and families with genetic conditions

PURPOSE

Individuals affected by genetic conditions are increasingly likely to seek information about inheritance and risk factors from their primary care physicians rather than a geneticist, but several studies suggest that few health care providers are capable of fulfilling that role or are comfortable doing so. Acknowledging that the adoption of new genetics knowledge and technologies is often patient-driven, we asked affected individuals and family members about their experiences in encounters with a variety of nongenetics-trained health care providers.

METHODS

Staff at the National Coalition for Health Professional Education in Genetics, the Genetic Alliance, and a University of Maryland graduate student in genetic counseling drafted a web-based survey. We recruited study participants from the Genetic Alliance, and a total of 5915 respondents completed the questionnaire between December 2004 and August 2005.

RESULTS

Overall, 64% of respondents reported receiving no genetics education materials from the provider type named most important in the management of the condition in the family. We present knowledge ratings for various provider types and themes emerging from written descriptions of positive and disappointing experiences.

CONCLUSION

We discuss the implications of these and other results for continuing genetics education and for clinical practice.

Managing incidental findings in human subjects research: analysis and recommendations

No consensus yet exists on how to handle incidental findings (IFs) in human subjects research. Yet empirical studies document IFs in a wide range of research studies, where IFs are findings beyond the aims of the study that are of potential health or reproductive importance to the individual research participant. This paper reports recommendations of a two-year project group funded by NIH to study how to manage IFs in genetic and genomic research, as well as imaging research. We conclude that researchers have an obligation to address the possibility of discovering IFs in their protocol and communications with the IRB, and in their consent forms and communications with research participants. Researchers should establish a pathway for handling IFs and communicate that to the IRB and research participants. We recommend a pathway and categorize IFs into those that must be disclosed to research participants, those that may be disclosed, and those that should not be disclosed.

Mutation detection in the ABCC6 gene and genotype-phenotype analysis in a large international case series affected by pseudoxanthoma elasticum

BACKGROUND

Pseudoxanthoma elasticum (PXE), an autosomal recessive disorder with considerable phenotypic variability, mainly affects the eyes, skin and cardiovascular system, characterised by dystrophic mineralization of connective tissues. It is caused by mutations in the ABCC6 (ATP binding cassette family C member 6) gene, which encodes MRP6 (multidrug resistance-associated protein 6).

OBJECTIVE

To investigate the mutation spectrum of ABCC6 and possible genotype-phenotype correlations.

METHODS

Mutation data were collected on an international case series of 270 patients with PXE (239 probands, 31 affected family members). A denaturing high-performance liquid chromatography-based assay was developed to screen for mutations in all 31 exons, eliminating pseudogene coamplification. In 134 patients with a known phenotype and both mutations identified, genotype-phenotype correlations were assessed.

RESULTS

In total, 316 mutant alleles in ABCC6, including 39 novel mutations, were identified in 239 probands. Mutations were found to cluster in exons 24 and 28, corresponding to the second nucleotide-binding fold and the last intracellular domain of the protein. Together with the recurrent R1141X and del23-29 mutations, these mutations accounted for 71.5% of the total individual mutations identified. Genotype-phenotype analysis failed to reveal a significant correlation between the types of mutations identified or their predicted effect on the expression of the protein and the age of onset and severity of the disease.

CONCLUSIONS

This study emphasises the principal role of ABCC6 mutations in the pathogenesis of PXE, but the reasons for phenotypic variability remain to be explored.

Advocacy groups as research organizations: the PXE International example

Advocacy organizations for genetic diseases are increasingly becoming involved in biomedical research, particularly translational research, in order to meet the needs of the individuals that they serve. PXE International, an advocacy organization for the disease pseudoxanthoma elasticum, provides an example of how research can be accelerated by these groups. It has adopted methods that were pioneered by other advocacy organizations, and has integrated these along with new approaches into franchizable elements. The model has been followed for other conditions and has led to the establishment of a common infrastructure to enable advocacy groups to initiate, conduct and accelerate research.

Development of a rapid, reliable genetic test for pseudoxanthoma elasticum

Mutations in the human ABCC6 gene cause pseudoxanthoma elasticum (PXE), a hereditary disorder that impacts the skin, eyes, and cardiovascular system. Currently, the diagnosis of PXE is based on physical findings and histological examination of a biopsy of affected skin. We have combined two simple, polymerase chain reaction (PCR)-based methods to develop a rapid, reliable genetic assay for the majority of known PXE mutations. After PCR amplification and heteroduplex formation, mutations in exon 24 and exon 28 of the ABCC6 gene were detected with Surveyor nuclease, which cleaves double-stranded DNA at any mismatch site. Mutations originating from deletion of a segment of the ABCC6 gene between exon 23 and exon 29 (ex23_ex29del) were detected by long-range PCR. Size analysis of digestion fragments and long-range PCR products was performed by agarose gel electrophoresis. The methods accurately identified mutations or the absence thereof in 16 affected individuals as confirmed by DNA sequencing. Fifteen patients had one or two point mutations, and two of these individuals carried the ex23_ex29del in their second allele. This mutation detection and mapping strategy provides a simple and reliable genetic assay to assist in diagnosis of PXE, differential diagnosis of PXE-like conditions, and study of PXE genetics.

Pseudoxanthoma elasticum-like phenotype with cutis laxa and multiple coagulation factor deficiency represents a separate genetic entity

Data on six patients with a Pseudoxanthoma Elasticum (PXE)-like phenotype, characterized by excessive skin folding (resembling cutis laxa) and a deficiency of the vitamin K-dependent clotting factors (II, VII, IX, and X) are presented. A comparison is made between the clinical, ultrastructural, and molecular findings in these patients and those seen in classic PXE and cutis laxa, respectively. Clinical overlap with PXE is obvious from the skin manifestations of yellowish papules or leathery plaques with dot-like depressions at presentation, angioid streaks and/or ocular peau d'orange, and fragmentation and calcification of elastic fibers in the dermis. Important phenotypic differences with PXE include much more severe skin laxity with spreading toward the trunk and limbs with thick, leathery skin folds rather than confinement to flexural areas, and no decrease in visual acuity. Moreover, detailed electron microscopic analyses revealed that alterations of elastic fibers as well as their mineralization were slightly different from those in classic PXE. Molecular analysis revealed neither causal mutations in the ABCC6 gene (ATP-binding cassette subfamily C member 6), which is responsible for PXE, nor in VKORC1 (vitamin K 2,3 epoxide reductase), known to be involved in vitamin K-dependent factor deficiency. However, the GGCX gene (gamma-glutamyl carboxylase), encoding an enzyme important for gamma-carboxylation of gla-proteins, harbored mutations in six out of seven patients analyzed. These findings all support the hypothesis that the disorder indeed represents a separate clinical and genetic entity, the molecular background of which remains to be unraveled.

A consumer perspective on forensic DNA banking

The currently evolving debate over ethical and legal approaches to DNA data banks reflects, in part, shifting societal perceptions of dividing lines between humanity and commodity, definitions of genetic inheritance between individuals and families, and the rights of the individual versus the rights of the community. Tensions arise whether the data bank has been created for medical or for forensic purposes. The authors, through their work as community activists described more fully below, have come to realize that the key to resolving these tensions and developing ethically acceptable DNA data bank practices is meaningful community engagement. Not unlike medical DNA data banks, personally identifiable DNA samples are routinely retained by states long after a convict's or arrestee's DNA profile has been derived from it and entered into the state database. The question arises, then, as to what, if any, non-forensic uses can these samples – ethically – be put.

Testicular Microlithiasis in Association with Pseudoxanthoma Elasticum

PURPOSE

To determine the presence of testicular microlithiasis in male subjects with pseudoxanthoma elasticum (PXE).

MATERIALS AND METHODS

Institutional review board approval was obtained for the prospective and retrospective components of this HIPAA-compliant study. Informed consent was obtained from all patients or their parents. Testicular ultrasonography (US) was performed in eight men aged 29-56 years and in one 13-year-old boy, all with confirmed PXE. Two radiologists reviewed the US images by consensus for testicular microlithiasis, testicular masses, and additional testicular abnormalities. Testicular microlithiasis was judged to be classic when at least five microliths were seen on a single US image and to be limited when fewer than five microliths were seen on all obtained US images. Urologic physiologic examinations were performed. A history and/or symptoms of testicular disease also were recorded at the time of examination. Similarly, the testicular US images obtained in two additional men, aged 48 and 59 years, and in another 13-year-old boy were retrospectively reviewed. Histopathologic testicular analysis was performed in one autopsy case.

RESULTS

Of the 12 participants, 11 (92%) had classic and one (8%) had limited testicular microlithiasis. None of the 12 participants had evidence of testicular malignancy at US or physical examination. Histopathologic analysis at autopsy revealed intratubular microlithiasis without the calcification of elastic fibers in arterial walls that is characteristic of cutaneous PXE.

CONCLUSION

Study findings suggested an association between PXE and testicular microlithiasis. It is possible that the testicular microlithiasis in male subjects who have PXE is related to the underlying PXE abnormality.

Ethical issues in identifying and recruiting participants for familial genetic research

Family-based research is essential to understanding the genetic and environmental etiology of human disease. The success of family-based research often depends on investigators' ability to identify, recruit, and achieve a high participation rate among eligible family members. However, recruitment of family members raises ethical concerns due to the tension between protecting participants' privacy and promoting research quality, and guidelines for these activities are not well established. The Cancer Genetics Network Bioethics Committee assembled a multidisciplinary group to explore the scientific and ethical issues that arise in the process of family-based recruitment. The group used a literature review as well as expert opinion to develop recommendations about appropriate approaches to identifying, contacting, and recruiting family members. We conclude that there is no single correct approach, but recommend a balanced approach that takes into account the nature of the particular study as well as its recruitment goals. Recruitment of family members should be viewed as part of the research protocol and should require appropriate informed consent of the already-enrolled participant. Investigators should inform prospective participants why they are being contacted, how information about them was obtained, and what will happen to that information if they decide not to participate. The recruitment process should also be sensitive to the fact that some individuals from families at increased genetic risk will have no prior knowledge of their risk status. These recommendations are put forward to promote further discussion about the advantages and disadvantages of various approaches to family-based recruitment. They suggest a framework for considering alternative recruitment strategies and their implications, as well as highlight areas in need of further empirical research.

Evidence for a founder effect for pseudoxanthoma elasticum in the Afrikaner population of South Africa

Pseudoxanthoma elasticum (PXE) is a heritable elastic tissue disorder recently shown to be attributable to mutations in the ABCC6 ( MRP6) gene. Whereas PXE has been identified in all ethnic groups studied to date, the prevalence of this disease in various populations is uncertain, although often assumed to be similar. A notable exception however is the prevalence of PXE among South African Afrikaners. A previous report has suggested that a founder effect may explain the higher prevalence of PXE in Afrikaners, a European-derived population that first settled in South Africa in the 17th century. To investigate this hypothesis, we performed haplotype and mutational analysis of DNA from 24 South African families of Afrikaner, British and Indian descent. Among the 17 Afrikaner families studied, three common haplotypes and six different disease-causing variants were identified. Three of these mutant alleles were missense variants, two were nonsense mutations and one was a single base-pair insertion. The most common variant accounted for 53% of the PXE alleles, whereas other mutant alleles appeared at lower frequencies ranging from 3% to 12%. Haplotype analysis of the Afrikaner families showed that the three most frequent mutations were identical-by-descent, indicating a founder origin of PXE in this population.

Empowering the public to be informed consumers of genetic technologies and services

OBJECTIVE

The genetics community, together with lay advocacy organizations and the general public, should strategically plan a focused, culturally competent, community-based public genetic literacy program.

METHODS

Inclusive of all stakeholders (consumers, professionals, disability communities, disenfranchised communities), society can advance this objective through a proactive, focused and coordinated outreach to build public awareness and understanding.

RESULTS

Genetic Alliance programs support consumers with genetic disorders, raise health professional awareness of their concerns, educate the public about emerging genetic information and technologies, increase access to high quality information resources, and advocate for public policies that ensure the promises of genetics.

CONCLUSION

The challenge before the genetics community is to be proactive, clear, and inclusive. The public should be empowered to make informed choices, allowing the potential benefits of genetic technologies and services to become manifest in improved healthcare and quality of life.

Researching the biology of PXE: partnering in the process

PXE International, a disease advocacy group, plays a central role as a catalyst in several research initiatives focused on the biology, epidemiology, and genetics of pseudoxanthoma elasticum (PXE). These initiatives accelerate research on PXE and provide a basis for several productive collaborative partnerships, including a particularly successful professional relationship between PXE International and the Laboratory of Matrix Pathobiology at the University of Hawaii. This partnership was critical in discovering the PXE gene and in beginning the elucidation of the pathobiology of this genetic disorder. Examination of some of the elements of this partnership may be useful for other lay advocacy/professional collaborations.