A view on clinical genetics and genomics in Spain: of challenges and opportunities.

A view on clinical genetics and genomics in Spain: of challenges and opportunities.

El documento de consentimiento informado para la realización de pruebas genéticas en el ámbito asistencial y en proyectos de investigación / The informed consent document for performing genetic tests in the healthcare environment and in research projects

Las pruebas genéticas (PG) proporcionan resultados que son para toda la vida y que tienen implicaciones no solo para el individuo sino para la familia, debiendo ir siempre acompañadas de consejo genético. Una de las herramientas que contribuye a que las PG se desarrollen en un entorno apropiado es el documento de consentimiento informado (DCI). El consentimiento informado (CI) tomado por el facultativo que prescribe la prueba es un medio para garantizar el acceso libre e informado y para que la persona entienda el propósito de la misma y las implicaciones de los resultados, así como para garantizar su derecho a recibir el consejo genético, ya que le da la oportunidad de hacer preguntas y también de manifestar su derecho a decidir qué información quiere conocer y cuál no quiere conocer en cualquier momento del proceso. En el presente trabajo se hace una reflexión sobre los principios éticos que fundamentan la toma del CI para la realización de PG y cómo nuestra sociedad ha plasmado en forma de regulaciones legales la protección de los valores éticos y de la dignidad y derechos fundamentales de los individuos con relación a las PG y a la información genética: Ley 14/2007 de 3 de julio de Investigación Biomédica. Como conclusiones se proponen 3 modelos de DCI: para la realización de PG en el contexto asistencial, con un consentimiento adicional en el caso de que el laboratorio clínico desee guardar las muestras excedentes para futuros usos en investigación y para un proyecto de investigación que incluya PG (AU)

The results obtained in genetic tests are valid for the whole life. They are important, not only for the individual, but also for the family. Genetic counselling must be an integral part of the genetic testing process. An important tool that must be used in order that genetic testing is performed properly is the informed consent document. This informed consent, obtained by the physician who requests the genetic tests, is a resource to ensure that the individual voluntarily agrees and understands their purposes, as well as the consequences of the results. It emphasises the rights to receive genetic counselling, and gives the opportunity to ask questions. It also mentions the right to choose what information the subject wishes or does not wish to know. This article considers the ethical principles that justify the informed consent and its inclusion in legal regulations in order to protect fundamental human rights concerning genetic testing and genetic information, such as Spanish law 14/2007 on Biomedical Research. As conclusions, 3 models of informed consent are proposed: one for genetic testing for health reasons; an additional consent in cases where the clinical laboratory wants to store the remaining samples for future uses in biomedical research, and for clinical trials that including genetic tests (AU)

Inherited metabolic rare disease.

Inherited metabolic disorders (IMD) represent a vast, diverse and heterogeneous collection of around 700 genetic diseases. They are caused by rare mutations that affect the function of individual proteins and are a significant cause of morbidity and mortality, especially in childhood. Difficulties in ascertaining cases and the increasing number of new disorders have hampered efforts to accumulate exhaustive epidemiological data. Nonetheless, recent studies quote the cumulative incidence of IMDs at around 1 in 800 live births. To understand the epidemiology of IMD we will consider in this chapter two types of epidemiological approaches. The first type, or the Analytical approaches, includes the function of genetic factors in the natural history and clinical variability of the disease, as well as the role of epigenetic, stochastic and environmental factors. The second type, or the Descriptive approaches, comprises methods of case ascertainment through the diagnosis of symptomatic patients and population screening, mainly newborn and carrier screening, as well as measures of disease frequency and resources for disease control and prevention (primary, secondary and tertiary).

A key role for the peroxisomal ABCD2 transporter in fatty acid homeostasis.

Peroxisomes are essential organelles exerting key functions in fatty acid metabolism such as the degradation of very long-chain fatty acids (VLCFAs). VLCFAs accumulate in X-adrenoleukodystrophy (X-ALD), a disease caused by deficiency of the Abcd1 peroxisomal transporter. Its closest homologue, Abcd2, exhibits a high degree of functional redundancy on the catabolism of VLCFA, being able to prevent X-ALD-related neurodegeneration in the mouse. In the search for specific roles of Abcd2, we screened fatty acid profiles in organs and primary neurons of mutant knockout mice lacking Abcd2 in basal conditions and under dietary challenges. Our results indicate that ABCD2 plays a role in the degradation of long-chain saturated and omega9-monounsaturated fatty acids and in the synthesis of docosahexanoic acid (DHA). Also, we demonstrated a defective VLCFA beta-oxidation ex vivo in brain slices of Abcd1 and Abcd2 knockouts, using radiolabeled hexacosanoic acid and the precursor of DHA as substrates. As DHA levels are inversely correlated with the incidence of Alzheimer's and several degenerative conditions, we suggest that ABCD2 may act as modulator/modifier gene and therapeutic target in rare and common human disorders.

Creatine transporter deficiency: prevalence among patients with mental retardation and pitfalls in metabolite screening.

OBJECTIVES: To report the prevalence of creatine transporter deficiency in males with mental retardation and to study whether a protein-rich food intake might be a potential diagnostic pitfall. DESIGN AND METHODS: We determined creatine/creatinine ratio in urine samples from 1600 unrelated male patients with mental retardation and/or autism. Urine creatine was analyzed by HPLC-MS/MS. RESULTS: Thirty-three of 1600 cases showed increased urine creatine/creatinine ratio. Four out of these thirty-three cases were definitively diagnosed with creatine transporter deficiency, while the other 29 were false positive results. Significantly higher values were observed for urine Cr/Crn ratio in healthy volunteers after a meal based on beef or oily fish as compared to eggs, pasta or salad (Wilcoxon test: p<0.005). CONCLUSIONS: False positive results may be observed in biochemical screening for creatine transporter deficiency, and they may be due to intake of meals rich in creatine prior to urine samples analysis.

Methods for the diagnosis of creatine deficiency syndromes: a comparative study.

The increasing number of patients with creatine deficiency syndromes (CDS) stresses the need to develop screening procedures for the identification these inherited disorders. Guanidinoacetate (GAA) and creatine (Cr) are reliable biochemical markers of CDS and several analytical methods to measure both metabolites have been developed. High-pressure liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) is quick and sensitive but, unlike HPLC and gas chromatography-mass spectrometry (GC/MS), it is unavailable in most laboratories. Thus, we decided to evaluate comparatively HPLC-MS/MS, GC/MS and HPLC methods, as well as to establish reference values in a healthy paediatric population. According to our results, these three methods may be suitable for analysing GAA in urine. Furthermore, Passing-Bablock plots showed good agreement among all three. However, when comparing the Cr/Crn ratio, our results revealed that while HPLC-MS/MS data were in agreement with those of GC/MS, a constant and proportional error was observed when compared with those of HPLC. Consequently, the Cr/Crn ratio obtained by the last method should be evaluated with caution. Our reference values for GAA and Cr/Crn ratio in urine negatively correlate with age. Concerning GAA and Cr measurements in plasma, it is interesting to note that in contrast to what was occurring in urine, GAA concentration increased significantly with age, while we did not find any significant difference for Cr values within the same age group.

Functional overlap between ABCD1 (ALD) and ABCD2 (ALDR) transporters: a therapeutic target for X-adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) is a severe neurodegenerative disease caused by loss of function of the peroxisomal transporter ABCD1 (ALD), which results in accumulation of very long chain fatty acids (VLCFAs) in organs and serum, central demyelination and peripheral axonopathy and Addison's disease. Knockout of the ALD gene in the mouse (ALD(-)) results in an adrenomyeloneuropathy-like disease (a late onset form of X-ALD). In the present study, we demonstrate that axonal damage occurs as first pathological event in this model, followed by myelin degeneration. We show that this phenotype can be modulated through expression levels of an ALD-related gene (ALDR/ABCD2), its closest paralogue and a target of PPARalpha and SREBP transcription factors. Overexpression of ALDR in ALD(-) mice prevents both VLCFAs accumulation and the neurodegenerative features, whereas double mutants for ALD and ALDR exhibit an earlier onset and more severe disease (including signs of inflammatory reaction) when compared with ALD single mutants. Thus, our results provide direct evidence for functional redundancy/overlap between both transporters in vivo and highlight ALDR as therapeutic target for treatment of X-ALD.

Neonatal screening.

Neonatal screening (NS) is a medical act in the context of preventive medicine aimed at the early identification of infants affected by certain conditions that threaten their life and long-term health, for which a timely intervention can lead to a significant reduction of morbidity, mortality and associated disabilities. It emerged three decades ago in the context of prevention of mental retardation. Since then, around 600 inborn metabolic disorders have been described and technological progress has been impressive; nevertheless only around 5% of the disorders have been the object of NS. The most frequently cited reasons for the limitation are low prevalence and the lack of treatment. The tandem mass spectrometry has come in place in recent years across the globe, expanding NS to include several disorders of intermediary metabolism. This has shown, in addition to a prevalence much higher than previously thought, the benefits of early detection. The present work is a review of NS, not only from the point of view of technological/medical achievements, but also considering other factors which will affect specific disease selection, according to the social and organizational infrastructure that may expand the borders of NS.