PHG Foundation | www.phgfoundation.org

26 August 2005The BMA published a report earlier this week on population screening and genetic testing. It reviews a number of well known issues: the impact of test results on insurance and employment, pharmacogenetics, pre-implantation genetic diagnosis and the benefits and pitfalls of screening programmes. Unfortunately, it provides little by way of new information or original recommendations.

A matter of much greater concern is its failure to encapsulate accurately the distinction between genetic screening and genetic testing. The first section of the report describes the essential characteristics of a screening programme and accurately sets out the differences between systematic and opportunistic screening. It makes clear that screening is a public health service in which members of a defined population are offered a test. It also encapsulates recent thinking about the nature of informed choice in screening, and how patients who are offered a screening test are encouraged to make a decision about whether or not they wish to participate.

The report then proceeds to characterise the distinction between genetic screening and genetic testing. It does so idiosyncratically, in a manner inconsistent with its own description of a screening programme. It suggests that the term screening should be used for testing members of a population for a disorder for which there is no prior evidence of the condition, although they may be part of a higher risk group, such as Ashkenazi Jews who are at risk of developing Tay Sachs disease, and reserves the term testing for those who know they are at risk, such as people belonging to families that may carry high penetrance genes associated with breast cancer or with a history of Huntington's disease. It is unclear why those who know they are at risk are seen by the authors to be conceptually different to those for which there is no prior evidence of the condition, although they may be part of a higher risk group. We suggest that the distinction that they try to make is unsound and has little relevance to the key difference between screening programmes and clinical tests, which is whether or not the test is explicitly offered to individuals as a public health service, as distinct from being used in the clinical setting when advice is sought by a patient.

It is our view that the term genetic screening should be used only when tests are offered (whether systematically or opportunistically) as part of a public health service, and genetic testing in all other circumstances. Our preference is that the testing of asymptomatic relatives of patients with inherited disorders should be referred to as cascade testing, although we concede that it would not be entirely inappropriate to call it cascade screening. We suggest that to use the word screening to refer generally to the testing of members of a population for a disorder for which there is no prior evidence of the condition (even if they may be part of a higher risk group) should be strongly avoided.

We regret that nowhere in the report is there any discussion about the definition or meaning of the term, a genetic test, since the term is capable of two entirely different meanings. The first meaning applies the word genetic to the disorder and confines itself to testing for genetic, that is inherited or heritable, disorders. In this sense any test for inherited disorders are genetic tests irrespective of the nature of the technology used. An ultrasound scan for adult polycystic disease of the kidney would be deemed a genetic test. The second meaning has the adjective genetic refer not to the disorder but to the technology used for the tests, thus equating genetic tests to tests based on DNA or chromosomes. Under this meaning, the use of a DNA based diagnostic to determine the increased risk of venous thromboembolism would be classified as a genetic test but not the use of an ultrasound scan for polycystic disease We believe that it is essential in any statement about genetic tests to make clear in which of these two senses it is being used.

A concentration by the report on the pitfalls of genetic screening is much to be regretted, since many of the ethical and social consequences that the report seeks to address are as much an issue for genetic testing as for genetic screening. The policy issues that arise when testing for inherited conditions are indeed different from those when testing for common complex disorders, but these differences are not those that distinguish screening from testing.

19 August 2005The Government has published its response to the House of Commons Science and Technology Committee’s report, Human Reproductive Technologies and the Law. The report, published in March 2005, examined the provisions of the Human Fertilisation and Embryology (HFE) Act 1990 and whether changes were needed in light of emerging technologies in assisted human reproduction as well as the knowledge gained over the last 15 years since the Act was written (see PHGU news story March 2005). The report also looked at the workings of the Human Fertilisation and Embryology Authority and made recommendations for change. 

The Government’s response, Human Reproductive Technologies and the Law: Government Response to the Report from the House of Commons Science and Technology Committee, examines the Committee’s recommendations in detail. Many of those recommendations, as well of those submitted by other stakeholders, have been taken up by the Government and can be found in the recent consultation, Review of the Human Fertilisation and Embryology Act (see PHGU news story August 2005). The Government did reject some specific recommendations by the Committee. For instance, the Government rejected the Committee’s suggestion that debate should continue on reproductive cloning. The Committee had argued that there might be instances where discussions should not be closed down. Also rejected was the suggestion that a twin track approach be instituted for those seeking donor gametes. With such a system, potential parents could choose between an identifiable or anonymous donor. The Government decided that this would give preference to the wishes of the parent rather than the interests of the child and would create an inequity of information for donor-conceived children.

The consultation period for the review of the HFE Act ends 25 November 2005. Information on how to respond is available on the consultation web site. 

16 August 2005The Department of Health (DH) has launched its consultation on the Human Fertilisation and Embryology (HFE) Act 1990. The Government acknowledges that the field of embryo research, assisted reproduction and their related technologies is fast-moving one and that the 1990 Act is in need of updating. The consultation seeks views from stakeholders and the public on areas on which the Act should be revised given, “… the rise of new technologies, changes in societal attitudes, international developments and the need to ensure effective regulation.” The consultation also takes into account the recent House of Commons Science and Technology Committee’s report, Human Reproductive Technologies and the Law. 

One of the issues raised is what the law should require in relation to the welfare of the child who may be born as a result of fertility treatment. Consideration of “…the welfare of the child who may be born as a result of the treatment (including the need of that child for a father), and of any other child who may be affected by the birth” is an explicit requirement of the Act. Currently, individuals must undergo an assessment of their suitability to receive treatment, including their commitment to raising children and the environment in which that child will be raised. Critics have noted that, “…the law does not intervene in the reproductive choices of people who are able to conceive naturally, it is therefore discriminatory to intervene where people happen to have fertility problems.” Others argue that helping people to reproduce adds a burden of responsibility to the clinicians. The Government therefore is seeking opinions as to whether considering the welfare of the child should be part of the HFE Act or should be a matter of ‘good medical practice’ not subject to regulation.

Other issues being explored include statutory maximum storage limits for gametes and embryos, information to be provided to donor-conceived people, surrogacy, sex-selection for non-medical reasons and the general criteria under which embryo screening and selection can be conducted (see related PHGU news story). The Government plans to regulate Internet services that supply gametes and seeks views on the extent of that regulation. Research using embryos is also discussed. Questions in this area include whether the creation of human-animal hybrid or chimera embryos should be allowed for research purposes, whether the current list of approved research purposes remains appropriate and whether scientists should be allowed to create embryos in order to treat serious disease. At this time, embryos may only be created for research into treatment for serious disease. Also, the consultation lays out plans for the new Regulatory Authority for Tissue and Embryos (RATE) and its functions. In 2008 RATE will replace the Human Fertilisation and Embryology Authority and the Human Tissue Authority.

The consultation ends on 25 November 2005. Information for submitting comments is available on the DH consultation website.

11 August 2005The Human Fertislation and Embryology Authority (HFEA) is seeking public opinions on whether the HFEA should extend its options for embryo screening, the BBC reports (BBC news story 11/08/05).  Currently, screening is available for parents with a family history of several serious conditions, such as Cystic Fibrosis or Huntington's disease.  Ten fertility clinics in the UK are licensed to test embryos.  Through the use of preimplantation genetic diagnosis (PGD), a woman's embryos can be screened for the gene for the condition in question.  Embryos free of the disease are chosen and reimplanted, thus avoiding passing on the faulty gene. 

Now, as more genes are being linked to the incidence of other diseases, such as various cancers, the HFEA expects more requests for embryo screening.  For example, last year the HFEA licensed a clinic at University College London to screen for familial adenomatous polyposis (FAP).  FAP has been linked to some bowel cancers.  The HFEA notes that their policy team has been reviewing this issue, aware that screening can now be done for inherited breast cancer, inherited ovarian cancer and hereditary non polyposis colon cancer, amongst others cancers.  But those who inherit these gene variants might never go on to suffer from the disease, as these conditions are not 'fully penetrant.' This has raised ethical questions.  In order to inform their policy decisions, the HFEA is asking the public their views about the acceptability of extending embryo screening to diseases that a person might develop in later life or might not develop at all.  As Angela McNab, Chief Executive of the HFEA explains, "What we are asking people is whether it is appropriate to use embryo screening technology to stop children being born with faulty genes when there is a chance they may never go on to suffer the cancer."  Opponents of PGD have already come out against the expanded screening.  Josephine Quintavalle, Director of the campaign group Comment on Reproductive Ethics claims that the screening procedures are 'engenic' in nature.  She stated, "...the only acceptable solution is to find effective cures for the diseases themselves not to kill the patients carrying them at the embryo or fetal stage. This is the ethical way forward in the application of our new genetic knowledge." 

The HFEA will be holding a public discussion on this issue in late autumn.  Further details will be posted on the HFEA website.

9 August 2005The European Union Conditional Mouse Mutant Program (EUCOMM) is to develop a comprehensive resource for mouse knockout strains, mice that have been genetically engineered to have mutations in specific genes. Such mice are essential for research into genetics and human disease, including as models of human disease; there are extensive similarities between the murine and human genomes. 

The intention is to create sets of murine embryonic stem (ES) cells carrying different knockout or null mutations (which render the gene in question inactive) in 20,000 different genes (the full mouse genome comprises 25,000 genes). Researchers would be able to order mice carrying the mutation of interest from the resource rather than having to engineer their own laboratory animals to contain the mutation, a slow and laborious process. This shared resource will also avoid scientists in different laboratories from having to create identical strains independently.

Work on the project, which has received £9million in European Commission funding, is to commence in 2006. Professor Steve Brown, director of the Medical Research Council's Mammalian Genetics Unit and head of one of the two UK teams involved in the project, said it would create a "tremendous resource" for the bio-medical research community (see BBC news report).

8 August 2005The European Commission has released its second report on the implementation of the Directive on the legal protection of biotechnological inventions (98/44/EC). The report, Development and Implications of Patent Law in the Field of Biotechnology and Genetic Engineering, details how the Directive has been implemented in Member States, noting that 21 countries have transposed it into national law and four have not: Italy, Luxembourg, Latvia and Lithuania. The report also addresses two issues raised in the Commission’s first report (published in 2002) on this topic: the scope of patents on gene sequences or partial gene sequences that have been isolated from the human body and the patentability of human pluripotent embryonic stem cells and of cell lines obtained from them. Rather than take action at this time, the Commission reports that it has decided to monitor continuing developments in both these areas.

On the first issue, Members States have differed by providing either a broad or limited scope of patent protection for human gene sequences. Most States provide ‘absolute product protection’, which covers the original disclosure in the patent application and possible future uses of the sequence. But two countries, France and Germany, have chosen a more restricted scope of protection. According to a statement by EuropaBio, the European Association for Bioindustries, these States have chosen to limit the patent protection to only the specific use disclosed in the application. In addition, France has banned the patenting of human gene sequences. Instead of judging whether or not these States have correctly implemented the Directive, the Commission has decided to monitor the economic consequences of their actions. EuropaBio has expressed its disappointment that the Commission has not sought better harmonisation in implementing the Directive. “Industry requires predictable rules across all Member States in order to attract the large R&D investments to meet societal needs,” stated Bo Hammer Jensen, Chair of EuropaBio’s Intellectual Property Working Group.

Inconsistency between the Member States is also clear in the second issue discussed in the report, that of the patentability of cell lines from human pluripotent stem cells. The Commission recognises that Member States differ significantly in their attitudes towards embryonic stem cell research. Due to these differences, the rapidity at which the field is progressing and the fact that the Directive allows Member States to refuse patents on the grounds of ordre public or morality, they have decided “…it is premature to give further definition or provide for further harmonisation in this area.” The Commission have launched an international study, Stem Cell Patents: European Patent Law and Ethics, to examine the ethical and legal aspects of stem cell patenting.

The Human Genetics Commission has reported the results of a public consultation on the use of genetics in reproductive decision-making (http://www.hgc.gov.uk/Client/news_item.asp?Newsid=40). The consultation ran for six months during 2004. Analysis of the 196 responses revealed a broad range of views on the ethical acceptability of prenatal diagnosis of genetic diseases, prenatal screening programmes, and preimplantation diagnosis (PGD), but somewhat more consensus on the practical issues of service provision within the National Health Service. There was general agreement, for example, that prenatal diagnostic testing and counselling offered by the specialist clinical genetics service (usually to couples known to be at high risk of an affected pregnancy) is of higher quality than prenatal population screening programmes offered to all pregnant women (for example, the Down syndrome screening programme). Many respondents felt that the quality of population screening programmes, and the experience of couples who participate in them, would be improved by better training of the staff involved, both in genetics and in the principles and practice of non-directive counselling. Medical professionals also need more time to devote to couples confronted with difficult decisions about screening.

Service improvements will obviously cost money but were seen as particularly important if prenatal screening programmes expand in the future to include a larger number of genetic conditions. Some felt that the future development of non-invasive prenatal testing technology, and the ability to carry out testing earlier in pregnancy, might alleviate these concerns, while others thought that easier testing procedures might make testing virtually automatic so that couples would find it harder to opt out.

Most respondents thought that preimplantation genetic diagnosis raised more issues of concern than prenatal diagnosis, mainly because PGD involves use of the difficult and expensive techniques of in vitro fertilisation and single-cell molecular diagnosis. It follows, by this argument, that the technique should not be available to all couples as a ‘right’, but that society should impose conditions and limitations. Regulation is already in place through the Human Fertilisation and Embryology Authority; it was felt by most that this stewardship should continue.

The consultation also canvassed views on other means of ‘selecting’ babies, for example by selection of embryo, egg or sperm donors. Interestingly, there was generally a more relaxed attitude to these methods because they were seen as more akin to the ‘natural’ process of selecting a reproductive mate. Some uneasiness about the participation of the private sector in offering services in this area, however, led respondents to conclude that it should be carefully regulated.

It is difficult to gauge to what extent the survey is representative of views in the UK public as a whole. By definition, the groups and individuals who responded were those with strong views on the subject and it may be that those with no direct experience of the issues are generally content to trust the ‘powers that be’ to regulate appropriately. The Human Genetics Commission will take the results of the consultation into account in preparing their report on genetics and reproductive decision-making, due later this year.

18 August 2005Stem cells have the ability to both self-renew and produce daughter cells committed to becoming specific specialist cell types. In vivo, stem cells are believed to be located within particular cellular niches that support their ability for self-renewal. Expansion of stem cell populations, both in vivo and in vitro, requires symmetrical cell division resulting in self-renewal, rather than asymmetric division producing both an identical clone and a specialised daughter cell. However, apart from embryonic stem (ES) cells, producing homogeneous, self-renewing cultures of stem cells ex vivo has proved to be problematic. Although epidermal and neural stem cells can be expanded in vitro this usually results in mixed cultures of both undifferentiated and differentiated cells. The reasons for this remain unclear but may be related to culture conditions or an intrinsic cellular bias towards asymmetric division. Neural cells can be maintained in culture as clusters, known as neurospheres, which are made up of progenitor cells mixed with differentiated astrocytes and neurons.  Although the use of neurospheres has proved to be useful in the study of the mammalian central nervous system, they also have significant limitations. The stem cells contained within neurospheres are not directly identifiable, and their actually relationship to CNS precursor cells in vivo has not been defined. Variations between cultures and their heterogeneous nature also means that inconsistent data is often produced from experiments involving neurospheres. Furthermore, neurospheres differentiate more readily into astrocytes than neurons in vitro, limiting their usefulness for drug discovery and therapeutic applications.

In their publication in PLoS Biology (Conti et al., (2005) PLoS Biology 3(9): e283), the authors report on the development of defined culture conditions enabling the production of symmetrically-dividing, self-renewing neural stem cells with full differentiation capacity.

The researchers initially worked on mouse ES cells. Neural stem cells were derived from these ES cells through growth in serum-free culture media. Transfer to basal media, followed by the addition of fibroblast growth factor-2 (FGF-2) and epidermal growth factor (EGF) resulted in these cells continuously proliferating without differentiating. Exposure to serum or the growth factor BMP4 stimulated these cells to differentiate into astrocytes or neurons, even after prolonged expansion. Neural stem cells able to differentiate in this way were obtained using this methodology from ten different ES cell lines. For all the lines examined, 95% of the cells expressed the immature neural marker nestin in the presence of FGF-2 and EGF. The group also investigated the role of each individual growth factor in maintaining proliferating neural stem cells. They established that when EGF was withdrawn from cultures of stem cells previously grown with both FGF-2 and EGF massive cell death occurred. This finding led them to conclude that EGF is essential for the maintenance of stem cells with the capacity for neurogenesis, and that it also supports self-renewal by suppressing apoptosis. The researchers also analysed the phenotypic properties of the undifferentiated neural stem cells, which were found to be similar to radial glial cells both in terms of cell morphology and relevant gene marker expression. Radial glia are only found during foetal development, but these insights indicate that they may have the potential to convert into stem cells.

The research group examined the effects of transplanting these cells into both foetal and adult rodent brains, by monitoring their expression of a green fluorescent protein (GFP) marker, and other specific neural markers such as nestin and GFAP. Their results indicate that the neural stem cells survived and differentiated in vivo, and importantly this occurred in a regulated manner and did not lead to the formation of cancerous tumours.

Finally, the group also attempted to replicate their rodent-based work using human ES and foetal cells. Although the methodology used to produce self-renewing mouse neural stem cells with differentiation capacity, was also effective when used with both types of human cells, proliferation was found to occur much more slowly. This indicated that their experimental technique may need to be refined to take account of species differences in order to obtain optimal levels of proliferation and differentiation.

Comment

The work carried out by the researchers at Edinburgh University is a significant advance in the production of useful cell lines that can be propagated over long periods of time, and whose capacity to differentiate can be controlled. The key to this process has been the elucidation of the role of EGF in cell cultures, and its ability in combination with FGF-2 to suppress differentiation and enable symmetrical self-renewal. Although further amendments to the researchers methodology will be required to produce equivalent results with human cells, their work provides valuable insights into the biology of tissue specific stem cells. Previously research on self-renewal could only be conducted on ES cell populations with this property, but the development of the new neural line will allow direct comparisons to be made between the two populations and should increase understanding of the mechanisms of lineage-restricted development and pluripotency. The development of the new cell lines also has potential for clinical usage. Although long-term studies of functionality in vivo will be essential, the work on rodents indicates that these neural stem cells have the potential to be used in cell replacement therapies in the future.

The full pulication can be found at: Conti L, Pollard SM, Gorba T, Reitano E, Toselli M, et al. (2005) Niche-Independent Symmetrical Self-Renewal of a Mammalian Tissue Stem Cell. PLoS Biol 3(9): e283

5 August 2005The genetic mutations underlying the development of the common, non-familial forms of breast cancer (the most common form of cancer among women in the UK) are an area of ongoing research. A region of human chromosome 8 (8p11-12) is frequently amplified in breast cancer cells, but the oncogene responsible for this has yet to be identified, although various candidate genes have been proposed. New research by Cambridge based scientists, published in Oncogene, presents evidence implicating four new candidate genes in breast cancer [Garcia MJ et al. (2005) Oncogene 24, 5235−5245].

The researchers analysed gene expression of the the 8p11−12 region in samples from 33 breast tumors, 20 ovarian tumors and 27 breast cancer cell lines at high resolution, using a technique called array comparative genomic hybridization, or array-CGH. Low resolution analysis of genome-wide copy-number changes was also performed, and identified certain regions commonly gained, lost or amplified in the tumour samples; 8p11−12 was one of the regions found to be amplified. In all, 13 samples showed amplification of 8p11−12: eight out of 33 breast tumours (24%), four out of 27 (15%) breast cancer cell lines and one out of 20 (5%) ovarian tumours. The size of the amplified region varied from 1-11 Mb. Some breast tumour samples also showed small regions of loss within 8p11−12. Fluorescence in situ hybridization (FISH) was performed on a selection of tumour samples, and showed reasonable agreement with the copy-number changes estimated by array-CGH.

Within a defined 1 Mb minimal common region of amplification, a total of six genes were identified: FLJ14299, C8orf2, PROSC, GPR124, BRF2 and RAB11FIP1; these do not include those previously proposed as putative oncogenes for the 8p11−12 amplicon. Real-time quantitative PCR (rtq-PCR) and/or oligo-microarray profiling was used to analyse expression of 10 genes in the 8p11−12 region (including FLJ14299 , GPR124 and RAB11FIP1) from 51 breast cell tumours and cell lines, to determine whether amplification of the region was associated with gene overexpression. 49 of these samples showed overexpression of most genes within the region. GPR124 and FLJ14299 showed moderate levels of increased expression compared with normal cells (13-fold and 4-fold) whilst RAB11FIP1 displayed a minimal increase of 1.6-fold. Comparison with gene expression in samples where the 8p11−12 region was not amplified suggested that expression levels of several genes including FLJ14299, RAB11FIP1, C8orf2 and BRF2 differed significantly between the two groups, although overexpression of GPR124 was not found to be specifically related to the presence of amplification and PROSC did not show consistent overexpression.

The authors propose that the genes FLJ14299, C8orf2, BRF2 and RAB11FIP are the most likely candidates for the oncogene driving amplification of 8p11−12 in the development of breast cancer. FLJ14299 is a novel gene containing zinc-finger domains, functional regions that bind to nucleic acids and which are present in some known tumour-related genes. BRF2 is the gene for a RNA polymerase III transcription factor complex subunit; RAB11FIP1 encodes the Rab coupling protein, which interacts with a group of enzymes involved in the regulation of intracellular transport vesicles. Little is known about the function of C8orf2. The authors also note that although the presence of 8p11−12 amplification in the 33 breast tumour samples showed no significant association with clinical features such as metastasis, recurrence or survival, larger numbers of samples would be required for a proper evaluation of any associations.

Comment: This research implicates a further four genes as potential oncogenes driving the development of breast cancer, although further research is required to validate any of these genes as a genuine oncogene. Moreover, as only around a quarter of the samples analysed showed amplification of the 8p11−12 region, even the definitive linking of one of these candidate genes with 8p11−12 amplification would only confirm one small contribution to the highly complex genetic processes that lead to the formation of breast cancer. However, it may be a a valuable piece of the puzzle. Lead author Professor Carlos Caldas has said that, although they have not identified any of the candidate genes as a key oncogene: "we know that women who have increased copies of this fragment of chromosome eight have a poor prognosis…We could use this to identify tumours that are more aggressive and target them with more aggressive treatment" (see BBC news report).

5 August 2005Priorities and standards in pharmacogenetic research. Need AC, Motulsky AG, Goldstein DB (2005). Nature Genetics 37, 671 - 681. Perspectives article, proposing that the future success of pharmacogenetics will depend upon recognition of the complexity of genetic (and environmental) influences on drug responses.

The genetics of addictions: uncovering the genes. Goldman D, Oroszi G and Ducci F (2005) Nature Reviews Genetics 6, 521-532. Review looking at the influence of genetic factors in addictions (the persistent, compulsive and uncontrolled use of a drug or an activity).

Genetic links between brain development and brain evolution. Gilbert SL, Dobyns WB and Lahn BT (2005). Nature Reviews Genetics 6, 581-590. Opinion piece suggesting that genes that regulate brain size during development are the key drivers of the evolutionary enlargement of the human brain, and proposing a method for the genetic analysis of human evolution.

The genetic and molecular bases of monogenic disorders affecting proteolytic systems. Richard I (2005) J Med Genet 2005; 42: 529-539. Review.

The location of constitutional neurofibromatosis 2 (NF2) splice site mutations is associated with the severity of NF2. Baser ME et al. (2005) J Med Genet 2005; 42: 540-546. Review.

How Malaria Has Affected the Human Genome and What Human Genetics Can Teach Us about Malaria. Kwiatkowski DP (2005) Am. J. Hum. Genet 77, 171-192. Review of progress in understanding the genetic factors that influence susceptibility and resistance to malaria, and the challenges for future, genome-wide association analysis.

The genetic epidemiology of human primary osteoarthritis: current status. Loughlin J (2005) Expert Rev. Mol. Med. Vol. 7, 1-12. Review.

Developmental biology: Tiny brakes for a growing heart. Bruneau BG (2005) Nature 436, 181-182. News and views article on the function of microRNAs (miRNAs) in the regulation of cardiac cell function.