Clouds over IMD? Perspectives for inherited metabolic diseases in adults from a retrospective cohort study in two Swiss adult metabolic clinics

Diagnostic accuracy and the first genotype-phenotype correlation in glycogen storage disease type V

BACKGROUND

Glycogen storage disease type V (GSDV) is an autosomal recessive metabolic condition caused by pathogenic PYGM variants. This is an underdiagnosed condition as it presents with exercise intolerance in children. We reviewed the GSDV cases of a tertiary hospital center to assess diagnostic timing/accuracy, as well as potential clinical/analytical predictors of such factors.

METHODS

We retrospectively reviewed all GSDV cases with follow-up in both Pediatric and Adult Metabolic Diseases consultations. We included 28 cases and assessed their hospital record for clinical information.

RESULTS

Over 90% of our cases had late diagnoses, with more than 50% being diagnosed in adulthood despite symptom onset in preschool (very late diagnosis). Diagnostic age was lower in patients exhibiting myoglobinuria. Interestingly, patients with a positive family history of GSDV had similar rates of very late diagnoses, likely since the index case was already detected very late in life. Finally, we observe that the R50* variant is associated with increased myoglobinuria and CK elevation, in a dosage-dependent manner.

CONCLUSION

We concluded that GSDV is severely underdiagnosed, and that some clinical and analytical aspects of the condition can be more indicative of this diagnosis. Furthermore, we propose for the first time a genotype-phenotype correlation in GSDV.

IMPACT

GSDV is a pediatric-onset metabolic disorder that is mostly diagnosed late in the adult age and commonly misdiagnosed. We observed the first genotype-phenotype correlation in GSDV, regarding the common R50* variant. Awareness of GSDV for pediatricians and the overall medical community is vital.

Diagnostic and Management Issues in Patients with Late-Onset Ornithine Transcarbamylase Deficiency

Ornithine transcarbamylase deficiency (OTCD) is the most common inherited disorder of the urea cycle and, in general, is transmitted as an X-linked recessive trait. Defects in the OTC gene cause an impairment in ureagenesis, resulting in hyperammonemia, which is a direct cause of brain damage and death. Patients with late-onset OTCD can develop symptoms from infancy to later childhood, adolescence or adulthood. Clinical manifestations of adults with OTCD vary in acuity. Clinical symptoms can be aggravated by metabolic stressors or the presence of a catabolic state, or due to increased demands upon the urea. A prompt diagnosis and relevant biochemical and genetic investigations allow the rapid introduction of the right treatment and prevent long-term complications and mortality. This narrative review outlines challenges in diagnosing and managing patients with late-onset OTCD.

Knowledge and awareness level of healthcare professional candidate students on inherited metabolic diseases: a cross-sectional study

BACKGROUND

Healthcare professionals play a key role in the diagnosis, treatment, and follow-up of inborn metabolic diseases. However, the level of inborn metabolic disease knowledge of prospective healthcare professional students in our country has not yet been determined. Therefore, this study aimed to evaluate the level of knowledge of healthcare professional candidate students about inborn metabolic diseases.

METHODS

The knowledge levels of 761 students enrolled in the Department of Nutrition and Dietetics, Child Development, Midwifery, Occupational Therapy, Audiology, Health Management and Social Work at Gülhane Faculty of Health Sciences, Health Sciences University, were evaluated through a questionnaire using a face-to-face interview technique. Correct answers to the questions measuring the level of knowledge were scored as "1", and incorrect answers were scored as "0".

RESULTS

The mean knowledge-level score of the individuals was 14.23 ± 4.56. A total of 56.0% of individuals had heard about inborn metabolic diseases before, 37.8% had heard of rare disease organizations/platforms before, and 16.8% had encountered an awareness campaign about inborn metabolic diseases. The level of exposure to awareness-raising campaigns, department of education, and grade level were shown to be factors affecting knowledge levels.

CONCLUSION

It is necessary to improve the awareness and knowledge levels of health professional candidates involved in the treatment of inborn metabolic diseases. Education curricula in health sciences faculties should be evaluated with this aspect.

Inherited metabolic disorders in adults: systematic review on patient characteristics and diagnostic yield of broad sequencing techniques (exome and genome sequencing)

BACKGROUND/OBJECTIVES

The timely diagnosis of inherited metabolic disorders (IMD) is essential for initiating treatment, prognostication and genetic testing of relatives. Recognition of IMD in adults is difficult, because phenotypes are different from those in children and influenced by symptoms from acquired conditions. This systematic literature review aims to answer the following questions: (1) What is the diagnostic yield of exome/genome sequencing (ES/GS) for IMD in adults with unsolved phenotypes? (2) What characteristics do adult patients diagnosed with IMD through ES/GS have?

METHODS

A systematic search was conducted using the following search terms (simplified): "Whole exome sequencing (WES)," "Whole genome sequencing (WGS)," "IMD," "diagnostics" and the 1,450 known metabolic genes derived from ICIMD. Data from 695 articles, including 27,702 patients, were analyzed using two different methods. First, the diagnostic yield for IMD in patients presenting with a similar phenotype was calculated. Secondly, the characteristics of patients diagnosed with IMD through ES/GS in adulthood were established.

RESULTS

The diagnostic yield of ES and/or GS for adult patients presenting with unexplained neurological symptoms is 11% and for those presenting with dyslipidemia, diabetes, auditory and cardiovascular symptoms 10, 9, 8 and 7%, respectively. IMD patients diagnosed in adulthood (n = 1,426), most frequently portray neurological symptoms (65%), specifically extrapyramidal/cerebellar symptoms (57%), intellectual disability/dementia/psychiatric symptoms (41%), pyramidal tract symptoms/myelopathy (37%), peripheral neuropathy (18%), and epileptic seizures (16%). The second most frequently observed symptoms were ophthalmological (21%). In 47% of the IMD diagnosed patients, symptoms from multiple organ systems were reported. On average, adult patients are diagnosed 15 years after first presenting symptoms. Disease-related abnormalities in metabolites in plasma, urine or cerebral spinal fluid were identified in 40% of all patients whom underwent metabolic screening. In 52% the diagnosis led to identification of affected family members with the same IMD.

CONCLUSION

ES and/or GS is likely to yield an IMD diagnosis in adult patients presenting with an unexplained neurological phenotype, as well as in patients with a phenotype involving multiple organ systems. If a gene panel does not yield a conclusive diagnosis, it is worthwhile to analyze all known disease genes. Further prospective research is needed to establish the best diagnostic approach (type and sequence of metabolic and genetic test) in adult patients presenting with a wide range of symptoms, suspected of having an IMD.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021295156.

Prevalence, Clinic-Etiological Spectrum and Outcome of Pediatric Metabolic Epilepsy - A Single Centre Experience

Introduction

Inborn errors of metabolism (IEM) are a rare cause of epilepsy in pediatric age group. Prompt diagnosis is essential, as some of these disorders are treatable.

Aim

To determine the prevalence, clinical, and etiological profile of metabolic epilepsy in children.

Methods

A prospective observational study of children with new onset seizures diagnosed as inherited metabolic disorder in a tertiary care hospital, South India.

Results

Among 10,778 children with new onset seizures, 63 (0.58%) had metabolic epilepsy. The male female ratio was 1.3:1. Onset of the seizures were in neonatal period in 12 (19%), infancy in 35 (55.6%), and between one and 5 years of age in 16 (25.4%) children. Generalised seizures were seen in 46 (73%), followed by multiple seizure types (31.7%). The associated clinical features included developmental delay in 37 (58.7%), hyperactivity in 7 (11%), microcephaly in 13 (20.6%), optic atrophy in 12 (19%), sparse hair and/or seborrheic dermatitis in 10 (15.9%), movement disorder in 7 (11%), and focal deficit in 27 (42.9%) patients. Magnetic resonance imaging brain was abnormal in 44 (69.8%) and diagnostic in 28 (44.4%) patients. Causative metabolic errors included vitamin responsive errors in 20 (31.7%), disorders of complex molecules in 13 (20.6%), amino acidopathies in 12 (19%), organic acidemias in 10 (16%), disorders of energy metabolism in 6 (9.5%), and peroxisomal disorders in 2 (3.2%) patients. With specific treatment, seizure freedom could be achieved in 45 (71%) children. Five children lost to follow-up and two died. Among the remaining 56 patients, 11 (19.6%) had a good neurological outcome.

Conclusion

Vitamin responsive epilepsies were the most frequent cause of metabolic epilepsy. Early diagnosis and prompt treatment is necessary as only one-fifth had a good neurological outcome.

Healthcare Transition in Inherited Metabolic Disorders-Is a Collaborative Approach between US and European Centers Possible?

Inherited metabolic diseases (IMDs) are rare heterogenous genetic conditions. Advanced technology and novel therapeutic developments have led to the improved life expectancy of patients with IMDs. Long-term, they require close surveillance from specialist adult metabolic providers. Healthcare transition (HCT) is the planned, purposeful process of preparing adolescents for adult-centered medical care and has been recognized globally as a necessary component of care for IMDs. Two recent surveys outlined barriers to the HCT in the US and the UK. The limited knowledge of IMDs among adult physicians was one of the barriers. Some work on specialty curriculum has started and aims to improve the structured training and awareness of rare diseases. Other barriers included social and legal aspects of adulthood, social, vocational and educational support for young adults, care fragmentation and insurance coverage. Although various HCT tools are available, they cannot always be standardized for IMDs. Despite the remarkable differences in the healthcare systems and physicians' training, collaboration among metabolic centers is possible. International rare disease alliance may enhance the patients' management via guidelines development and standardized training for adult metabolic providers.

Training competencies in adult metabolic medicine: A survey of working adult metabolic medicine physicians

The rapid expansion of the number of adult patients with inherited metabolic diseases (IMDs) has created demand for physicians with expertise in the field of adult metabolic medicine (AMM). Unfortunately, existing accredited training programs in this field are rare, and training programs in pediatric metabolic medicine cannot fully meet the needs of AMM physicians as the types of patients and the problems they face are different in the adult setting. We surveyed a group of working practitioners in AMM for input on what medical expert competencies they feel should be included as part of training programs in AMM. Through a modified Delphi process, 66 physicians from six continents reached consensus on a comprehensive list of training competencies in AMM. This list includes competencies from the fields of adult internal medicine, neurology, medical genetics, and pediatric metabolic medicine but also includes competencies not found in any of those programs, leading to the conclusion that the training needs for specialists in AMM cannot be met from any of these existing programs. We propose that AMM be considered a subspecialty separate from pediatric metabolic medicine and that accredited training programs in AMM be created using these medical expert competencies as part of a broader program design.

The current state of adult metabolic medicine in the United States: Results of a nationwide survey

PURPOSE

Patients with inherited metabolic disorders (IMDs) now have improved health outcomes and increased survival into adulthood. There is scant evidence on managing adults with IMDs. We present an analysis of current care practices for adults with IMDs in the United States.

METHODS

We created and distributed an online survey to US members of the Society of Inherited Metabolic Disorders. The survey addressed ambulatory care, acute management, and health care transition (HCT) practices of adults with IMDs.

RESULTS

The survey was completed by 91 providers from 73 institutions. Most adult patients with IMDs receive lifelong care from a single metabolic clinician, predominantly in pediatric clinic settings. Adults receive comprehensive ambulatory metabolic care, but fewer trainees participate compared with pediatric visits. Most acute IMD management occurs in pediatric hospitals. Clinician comfort with HCT increased the frequency of HCT planning. Overall, all respondents felt that providing specialized care to adults with IMDs is high value.

CONCLUSION

Our survey demonstrates the paucity of clinical resources dedicated to adult metabolic medicine. Care is fragmented and varies by medical system. Interest in HCT is robust but would benefit from standardized practices. Our findings reinforce the need for greater focus on adult metabolic medicine in the United States.

Multidisciplinary Care of Patients with Inherited Metabolic Diseases and Epilepsy: Current Perspectives

More than 650 inherited metabolic diseases may present with epilepsy or seizures. These diseases are often multisystem, life-long and induce complex needs of patients and families. Multidisciplinary care involves all stages of disease management: diagnostics, specific or symptomatic, acute and chronic treatments, and integrated care that takes into account not only medical, but also manifold psychosocial, educational, vocational and other needs of patients and their caregivers. Care coordination is indispensable to ensure smooth transitions of care across life and disease stages, including management of emergencies, transition from pediatric to adult services and palliative care. Care pathways are highly diverse and have to find the right balance between highly specialized and locally provided services. While multidisciplinary teams consist of many professionals, a named supervising physician in a highly specialized healthcare setting and a care coordinator are highly important. As the greatest burden of care always falls onto the shoulders of patients and/or families, patient empowerment should be a part of every care pathway and include provision of required information, involvement into common decision-making, patient’s and family’s education, support for self-management, liaison with peer support groups and emotional/ psychological support. Due to the rarity and complexity of these diseases, sufficient expertise may not be available in a national healthcare system and cross-border services (virtual or physical) in the recently developed European Reference Networks should be ensured through the proper organization of referral systems in each EU and EEA country. Finally, digital technologies are particularly important in the provision of services for patients with rare diseases and can significantly increase the availability of highly specialized services and expertise.

[Chronic Fatigue: When to Suspect an Inherited Metabolic Disease?]

Chronic Fatigue: When to Suspect an Inherited Metabolic Disease? Abstract. Chronic fatigue is a non-specific symptom, frequent in outpatient adults' consultations. Persistent physical fatigue of unknown etiology should prompt the search for rare diseases including inherited metabolic disorder (IMD) after elimination of common causes. The main characteristic of chronic fatigue in IMD is its dynamic nature, worsened by circumstances leading to an increased metabolism such as physical exertion, cold, fasting or infection. IMD leading to chronic fatigue are metabolic myopathies, in particular glycogen storage disease affecting muscle, fatty acid oxidation disorders and mitochondrial diseases. The diagnosis is confirmed by specific biochemical and/or molecular analyzes with multidisciplinary management.

[Chronic Fatigue: When to Suspect an Inherited Metabolic Disease?]

Chronic Fatigue: When to Suspect an Inherited Metabolic Disease? Abstract. Chronic fatigue is a non-specific symptom, frequent in outpatient adults' consultations. Persistent physical fatigue of unknown etiology should prompt the search for rare diseases including inherited metabolic disorder (IMD) after elimination of common causes. The main characteristic of chronic fatigue in IMD is its dynamic nature, worsened by circumstances leading to an increased metabolism such as physical exertion, cold, fasting or infection. IMD leading to chronic fatigue are metabolic myopathies, in particular glycogen storage disease affecting muscle, fatty acid oxidation disorders and mitochondrial diseases. The diagnosis is confirmed by specific biochemical and/or molecular analyzes with multidisciplinary management.