Narrowing the gap of personalized medicine in emerging countries: the case of multiple endocrine neoplasias in Brazil

Precision Medicine and Obesity

Obesity is a chronic, relapsing, and multifactorial disease, with a rising prevalence and an associated high economic burden. Achieving successful and sustained weight loss outcomes with current interventions is challenging. This is due, at least in part, to the disease's heterogenous pathophysiology that is yet to be completely understood. Technological advances and greater capabilities for the extraction and storage of information have facilitated the application of precision medicine. Several precision medicine initiatives have been proposed to improve obesity outcomes. Most of these initiatives are based on -omics technologies. Although the data generated from these technologies have led to developing hypotheses that may explain the underpinnings of obesity, their applicability to the clinical practice is yet to be determined. There are other initiatives that have identified quantitative or qualitative physiologic traits that can be targeted and that could have a more immediate clinical impact. This review aims to provide a perspective of current initiatives for precision medicine for obesity.

A. Phosphodiesterases and cAMP Pathway in Pituitary Diseases

Human phosphodiesterases (PDEs) comprise a complex superfamily of enzymes derived from 24 genes separated into 11 PDE gene families (PDEs 1-11), expressed in different tissues and cells, including heart and brain. The isoforms PDE4, PDE7, and PDE8 are specific for the second messenger cAMP, which is responsible for mediating diverse physiological actions involving different hormones and neurotransmitters. The cAMP pathway plays an important role in the development and function of endocrine tissues while phosphodiesterases are responsible for ensuring the appropriate intensity of the actions of this pathway by hydrolyzing cAMP to its inactive form 5'-AMP. PDE1, PDE2, PDE4, and PDE11A are highly expressed in the pituitary, and overexpression of some PDE4 isoforms have been demonstrated in different pituitary adenoma subtypes. This observed over-expression in pituitary adenomas, although of unknown etiology, has been considered a compensatory response to tumorigenesis. PDE4A4/5 has a unique interaction with the co-chaperone aryl hydrocarbon receptor-interacting protein (AIP), a protein implicated in somatotroph tumorigenesis via germline loss-of-function mutations. Based on the association of low PDE4A4 expression with germline AIP-mutation-positive samples, the available data suggest that lack of AIP hinders the upregulation of PDE4A4 protein seen in sporadic somatotrophinomas. This unique disturbance of the cAMP-PDE pathway observed in the majority of AIP-mutation positive adenomas could contribute to their well-described poor response to somatostatin analogs and may support a role in tumorigenesis.

Precision Medicine: Changing the way we think about healthcare

Health care has changed since the decline in mortality caused by infectious diseases as well as chronic and non-contagious diseases, with a direct impact on the cost of public health and individual health care. We must now transition from traditional reactive medicine based on symptoms, diagnosis and treatment to a system that targets the disease before it occurs and, if it cannot be avoided, treats the disease in a personalized manner. Precision Medicine is that new way of thinking about medicine. In this paper, we performed a thorough review of the literature to present an updated review on the subject, discussing the impact of the use of genetics and genomics in the care process as well as medical education, clinical research and ethical issues. The Precision Medicine model is expanded upon in this article to include its principles of prediction, prevention, personalization and participation. Finally, we discuss Precision Medicine in various specialty fields and how it has been implemented in developing countries and its effects on public health and medical education.

Costs of genetic testing: Supporting Brazilian Public Policies for the incorporating of molecular diagnostic technologies

This study identifies and describes the operating costs associated with the molecular diagnosis of diseases, such as hereditary cancer. To approximate the costs associated with these tests, data informed by Standard Operating Procedures for various techniques was collected from hospital software and a survey of market prices. Costs were established for four scenarios of capacity utilization to represent the possibility of suboptimal use in research laboratories. Cost description was based on a single site. The results show that only one technique was not impacted by rising costs due to underutilized capacity. Several common techniques were considerably more expensive at 30% capacity, including polymerase chain reaction (180%), microsatellite instability analysis (181%), gene rearrangement analysis by multiplex ligation probe amplification (412%), non-labeled sequencing (173%), and quantitation of nucleic acids (169%). These findings should be relevant for the definition of public policies and suggest that investment of public funds in the establishment of centralized diagnostic research centers would reduce costs to the Public Health System.

Genomic analysis in the clinic: benefits and challenges for health care professionals and patients in Brazil

Despite significant advances in the diagnosis and treatment of genetic diseases in the last two decades, there is still a significant proportion where a causative mutation cannot be identified and a definitive genetic diagnosis remains elusive. New genome-wide or high-throughput multiple gene tests have brought new hope to the field, since they can offer fast, cost-effective and comprehensive analysis of genetic variation. This is particularly interesting in disorders with high genetic heterogeneity. There are, however, limitations and concerns regarding the implementation of genomic analysis in everyday clinical practice, including some particular to emerging and developing economies, as Brazil. They include the limited number of actionable genetic variants known to date, difficulties in determining the clinical validity and utility of novel variants, growth of direct-to-consumer genetic testing using a genomic approach and lack of proper training of health care professionals to adequately request, interpret and use genetic information. Despite all these concerns and limitations, the availability of genomic tests has grown at an extremely rapid pace and commercially available services include initiatives in almost all areas of clinical genetics, including newborn and carrier screening. We discuss the benefits and limitations of genomic testing, as well as the ethical implications and the challenges for genetic education and enough available and qualified health care professionals, to ensure the adequate process of informed consent, meaningful interpretation and use of genomic data and definition of a clear regulatory framework in the particular context of Brazil.

A differential diagnosis of inherited endocrine tumors and their tumor counterparts

Inherited endocrine tumors have been increasingly recognized in clinical practice, although some difficulties still exist in differentiating these conditions from their sporadic endocrine tumor counterparts. Here, we list the 12 main topics that could add helpful information and clues for performing an early differential diagnosis to distinguish between these conditions. The early diagnosis of patients with inherited endocrine tumors may be performed either clinically or by mutation analysis in at-risk individuals. Early detection usually has a large impact in tumor management, allowing preventive clinical or surgical therapy in most cases. Advice for the clinical and surgical management of inherited endocrine tumors is also discussed. In addition, recent clinical and genetic advances for 17 different forms of inherited endocrine tumors are briefly reviewed.

Total parathyroidectomy in a large cohort of cases with hyperparathyroidism associated with multiple endocrine neoplasia type 1: experience from a single academic center

Most cases of sporadic primary hyperparathyroidism present disturbances in a single parathyroid gland and the surgery of choice is adenomectomy. Conversely, hyperparathyroidism associated with multiple endocrine neoplasia type 1 (hyperparathyroidism/multiple endocrine neoplasia type 1) is an asynchronic, asymmetrical multiglandular disease and it is surgically approached by either subtotal parathyroidectomy or total parathyroidectomy followed by parathyroid auto-implant to the forearm. In skilful hands, the efficacy of both approaches is similar and both should be complemented by prophylactic thymectomy. In a single academic center, 83 cases of hyperparathyroidism/ multiple endocrine neoplasia type 1 were operated on from 1987 to 2010 and our first surgical choice was total parathyroidectomy followed by parathyroid auto-implant to the non-dominant forearm and, since 1997, associated transcervical thymectomy to prevent thymic carcinoid. Overall, 40% of patients were given calcium replacement (mean intake 1.6 g/day) during the first months after surgery, and this fell to 28% in patients with longer follow-up. These findings indicate that several months may be needed in order to achieve a proper secretion by the parathyroid auto-implant. Hyperparathyroidism recurrence was observed in up to 15% of cases several years after the initial surgery. Thus, long-term follow-up is recommended for such cases. We conclude that, despite a tendency to subtotal parathyroidectomy worldwide, total parathyroidectomy followed by parathyroid auto-implant is a valid surgical option to treat hyperparathyroidism/multiple endocrine neoplasia type 1. Larger comparative systematic studies are needed to define the best surgical approach to hyperparathyroidism/multiple endocrine neoplasia type 1.