Comprehensive Genetic Service Research Articles

Medical Genetics in Brazil in the 21st Century: A Thriving Specialty and Its Incorporation in Public Health Policies.

Brazil is a continent-size country with 203 million inhabitants, classified as a developing upper-middle-income country, although inequities remain significant. Most of the population is assisted by the public Unified Health System (SUS), along with a thriving private health sector. Congenital malformations are the second leading cause of infant mortality and chronic/genetic disorders and a significant burden in hospital admissions. The past two decades have been crucial for formalizing medical genetics as a recognized medical specialty in the SUS, as well as for implementing a new health policy by the Ministry of Health for comprehensive care for rare diseases. These public health policies had the broad support of the Brazilian Society of Medical Genetics and Genomics and patient organizations. Most comprehensive genetic services are concentrated in large urban centers in the South and Southeast regions of Brazil; with this new policy, new services throughout the country are progressively being integrated. The number of medical geneticists increased by 103% in a decade. Details on the policy and an overview of the availability of services, testing, human resources, newborn screening, research projects, patient organizations, and relevant issues regarding medical genetics in this vast and diverse country are presented.

Identification of novel mutations in TPK1 and SLC19A3 genes in families exhibiting thiamine metabolism dysfunction syndrome

Background and aimsThe occurrence of thiamine metabolism dysfunction syndrome (THMD), a rare autosomal recessive condition, may be linked to various mutations found in the TPK1 and SLC19A3 genes. The disease chiefly manifests through ataxia, muscle hypotonia, abrupt or subacute onset encephalopathy, and a decline in developmental milestones achieved during the early stages of infancy. We present findings from an investigation that involved two individuals from Iran, both of whom experienced seizures along with ataxia and hypotonia. The underlying genetic causes were found with the use of next-generation sequencing (NGS) technology, which has facilitated the detection of causal changes in a variety of genetic disorders. Material and methodsThe selection of cases for this study was based on the phenotypic and genetic information that was obtainable from the Center for Comprehensive Genetic Services. The genetic basis for the problems observed among the participants was determined through the application of whole-exome sequencing (WES). Subsequently, sanger sequencing was employed as a means of validating any identified variations suspected to be causative. ResultsThe first patient exhibited a homozygous mutation in the TPK1 gene, NM_022445.4:c.224 T > A:p.I75 N, resulting in the substitution of isoleucine for asparagine at position 75 (p.I75 N). In our investigation, patient 2 exhibited a homozygous variant, NM_025243.4:c.1385dupA:pY462X, within the SLC19A3 gene. ConclusionsCollectively, when presented with patients showcasing ataxia, encephalopathy, and basal ganglia necrosis, it is essential to account for thiamine deficiency in light of the potential advantages of prompt intervention. At times, it may be feasible to rectify this deficiency through the timely administration of thiamine dosages. Accordingly, based on the results of the current investigation, these variations may be useful for the diagnosis and management of patients with THMD.

Broadening the phenotype and genotype spectrum of novel mutations in pontocerebellar hypoplasia with a comprehensive molecular literature review

BackgroundPontocerebellar hypoplasia is an umbrella term describing a heterogeneous group of prenatal neurodegenerative disorders mostly affecting the pons and cerebellum, with 17 types associated with 25 genes. However, some types of PCH lack sufficient information, which highlights the importance of investigating and introducing more cases to further elucidate the clinical, radiological, and biochemical features of these disorders. The aim of this study is to provide an in-depth review of PCH and to identify disease genes and their inheritance patterns in 12 distinct Iranian families with clinically confirmed PCH.MethodsCases included in this study were selected based on their phenotypic and genetic information available at the Center for Comprehensive Genetic Services. Whole-exome sequencing (WES) was used to discover the underlying genetic etiology of participants' problems, and Sanger sequencing was utilized to confirm any suspected alterations. We also conducted a comprehensive molecular literature review to outline the genetic features of the various subtypes of PCH.ResultsThis study classified and described the underlying etiology of PCH into three categories based on the genes involved. Twelve patients also were included, eleven of whom were from consanguineous parents. Ten different variations in 8 genes were found, all of which related to different types of PCH. Six novel variations were reported, including SEPSECS, TSEN2, TSEN54, AMPD2, TOE1, and CLP1. Almost all patients presented with developmental delay, hypotonia, seizure, and microcephaly being common features. Strabismus and elevation in lactate levels in MR spectroscopy were novel phenotypes for the first time in PCH types 7 and 9.ConclusionsThis study merges previously documented phenotypes and genotypes with unique novel ones. Due to the diversity in PCH, we provided guidance for detecting and diagnosing these heterogeneous groups of disorders. Moreover, since certain critical conditions, such as spinal muscular atrophy, can be a differential diagnosis, providing cases with novel variations and clinical findings could further expand the genetic and clinical spectrum of these diseases and help in better diagnosis. Therefore, six novel genetic variants and novel clinical and paraclinical findings have been reported for the first time. Further studies are needed to elucidate the underlying mechanisms and potential therapeutic targets for PCH.

Implementation of Public Funded Genome Sequencing in Evaluation of Fetal Structural Anomalies.

With the advancements in prenatal diagnostics, genome sequencing is now incorporated into clinical use to maximize the diagnostic yield following uninformative conventional tests (karyotype and chromosomal microarray analysis). Hong Kong started publicly funded prenatal genomic sequencing as a sequential test in the investigation of fetal structural anomalies in April 2021. The objective of the study was to evaluate the clinical performance and usefulness of this new service over one year. We established a web-based multidisciplinary team to facilitate case selection among the expert members. We retrospectively analyzed the fetal phenotypes, test results, turnaround time and clinical impact in the first 15 whole exome sequencing and 14 whole genome sequencing. Overall, the molecular diagnostic rate was 37.9% (11/29). De novo autosomal dominant disorders accounted for 72.7% (8/11), inherited autosomal recessive disorders for 18.2% (2/11), and inherited X-linked disorders for 9.1% (1/11). The median turnaround time for ongoing pregnancy was 19.5 days (range, 13-31 days). Our study showed an overall clinical impact of 55.2% (16/29), which influenced reproductive decision-making in four cases, guided perinatal management in two cases and helped future family planning in ten cases. In conclusion, our findings support the important role of genome sequencing services in the prenatal diagnosis of fetal structural anomalies in a population setting. It is important to adopt a multidisciplinary team approach to support the comprehensive genetic service.

Importance of Studying Older Siblings of Patients Identified by Newborn Screening: a Single-Center Experience in Mexico

Abstract Introduction: Any abnormal newborn screening (NBS) test should be subjected to appropriate diagnostic tests and should be followed. Once the newborn has been diagnosed and treated, the family should receive comprehensive genetic services. Aim: To present the experience of studying older siblings of patients with inborn errors of metabolism (IEM) identified by NBS in a single-national follow-up reference center. Methods: A retrospective analysis of medical files of the IEM patients detected by NBS was conducted. All those older siblings who tested positive for the same IEM of the patient detected by newborn screening were included. Results: A total of 26 positive siblings from 18 families with seven different IEM were found (phenylketonuria, argininemia, glucose-6-phosphate dehydrogenase deficiency, 3-methylcrotonyl-CoA carboxylase deficiency, dihydropteridine reductase deficiency, tyrosinemia type 3, and medium chain acyl-CoA dehydrogenase deficiency). The age range of the affected siblings was 2 to 19 years old, with a mean age of 8.5 years. Ten older siblings (38.5%) had clinical consequences for the disease, including severe intellectual disability. Conclusions: It is necessary to study older siblings, and family history and genetic counseling of all NBS-detected families should be recommended, especially in countries where expanded NBS programs are beginning.

Prenatal diagnosis in Belgium.

Prenatal diagnoses (PND) in Belgium are performed exclusively in licensed centres of medical genetics linked to university hospitals. These centres of genetics provide comprehensive genetic services which include, in addition to genetic tests, genetic counselling and moral support. These services are accessible to all residents in Belgium through coverage by the social security. PND has become a widely accepted procedure by the public and the health professionals, and has achieved significant prevention of birth defects, mainly chromosome abnormalities. The main problems involved in PND in Belgium are (1) the lack of regulations about indications for PND and (2) insufficient education in medical genetics in medical schools. It is hoped that the basic organisation of PND in Belgium will prevail in the future, with the proposed improvements.

Comprehensive genetic testing for primary immunodeficiency disorders in a tertiary hospital: 10-year experience in Auckland, New Zealand.

Background and purposeNew Zealand is a developed geographically isolated country in the South Pacific with a population of 4.4 million. Genetic diagnosis is the standard of care for most patients with primary immunodeficiency disorders (PIDs).MethodsSince 2005, we have offered a comprehensive genetic testing service for PIDs and other immune-related disorders with a published sequence. Here we present results for this program, over the first decade, between 2005 and 2014.ResultsWe undertook testing in 228 index cases and 32 carriers during this time. The three most common test requests were for X-linked lymphoproliferative (XLP), tumour necrosis factor receptor associated periodic syndrome (TRAPS) and haemophagocytic lymphohistiocytosis (HLH). Of the 32 suspected XLP cases, positive diagnoses were established in only 2 patients. In contrast, genetic defects in 8 of 11 patients with suspected X-linked agammaglobulinemia (XLA) were confirmed. Most XLA patients were initially identified from absence of B cells. Overall, positive diagnoses were made in about 23% of all tests requested. The diagnostic rate was lowest for several conditions with locus heterogeneity.ConclusionsThorough clinical characterisation of patients can assist in prioritising which genes should be tested. The clinician-driven customised comprehensive genetic service has worked effectively for New Zealand. Next generation sequencing will play an increasing role in disorders with locus heterogeneity.

Erratum to: Genetic services and testing in Brazil

Brazil is a continent-size country with around 190 million inhabitants, the largest and most populous in South America. It is classified as a developing upper middle-income country and having considerable growth, although inequality remains significant. The health system is mixed; most of the population is served by the public Unified Health System ("Sistema Único de Saúde", SUS) and there is a thriving private health sector. The country faces multiple obstacles to improve and expand genetic services, due to its wide territory, sociocultural inequalities and major basic health problems. Most comprehensive genetic services are concentrated in large urban centers in the South and Southeast regions, mainly in tertiary care university hospitals. Demand for genetic services has increased and congenital malformations has been the second cause of infant mortality since 2000, but such data did not determine government policies or initiatives for the prevention and management of this group of problems until 2004, when the process for introducing medical genetics as a health policy by the Ministry of Health began. Details on the policy and an overview on congenital and genetic diseases, the state and availability of genetic services, genetic testing, medical genetics laboratories, training of human resources in medical genetics, newborn screening program, genetics networks, special care facilities, as well as educational, social and support programs for disabled people, research priorities in genetics and genomics, patient organizations and relevant issues regarding the challenge of implementing a comprehensive care policy in clinical genetics in this vast and diverse country are presented.

Cardiovascular genetics—redefining the role of the clinical geneticist

In an effort to find a solution for the problem of providing comprehensive genetic services in the current managed care environment, The Golisano Children's Hospital at Strong, University of Rochester Medical Center decided to test a new role for the clinical geneticist. A board certified clinical geneticist/dysmorphologist was hired to build a new cardiovascular genetics program within the division of pediatric cardiology. This is a novel approach since most divisions of pediatric cardiology do not have a specifically designated geneticist as a member of their division. As one of seven cardiovascular genetics clinics in the United States (nine world wide) the Cardiovascular Genetics Program at The Children's Heart Center provides genetic services to a targeted, complex group of patients. In the first 9 months, the overall utilization (number of patient slots available/number of patients seen) of the clinic is 81% with a show rate of 85%. The program provides consultative services to pediatric cardiology as well as pediatric and adult medicine within the hospital and the community. The pediatric cardiovascular surgery service is regionalized including patients from Syracuse, Rochester and Buffalo, New York areas. The Cardiovascular Genetics Program offers initial, second opinion and follow-up evaluations to this entire upstate New York region. As a consultative service the Program supplies the PCP and/or surgeon with a comprehensive management plan in addition to the diagnostic evaluation. The PCP/surgeon executes the plan with support from the genetics staff as needed. It is the comprehensive nature of the management plan provided to the caregivers that improves quality of care and thus, outcome, even when a definitive diagnosis has not been established.

Prenatal genetic counseling: ethical and legal interfaces with the nurse's role.

Prenatal genetic counseling is a newly emerging clinical specialty that is being developed in response to the public's increased demand for comprehensive genetic services. Nurses who are choosing to function in this new clinical specialty as genetic counselors are finding that they are confronted with a unique set of problems and issues that have both ethical and legal implications for their practice. This paper examines the nature of the nurse's role as genetic counselor, explores the types of ethical decisions nurses are likely to confront, and reviews two court cases that have legal implications for nurses functioning in this highly specialized role.