Publications by authors named "Clara Van Karnebeek"

Inborn errors of metabolism (IEMs) are rare genetic conditions with significant morbidity and mortality. Technological advances have increased therapeutic options, making it challenging to remain up to date. A centralized therapy knowledgebase is needed for early diagnosis and targeted treatment.

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Gyrate atrophy of the choroid and retina (GACR, OMIM #258870) is a rare inherited metabolic disorder characterized by progressive chorioretinal degeneration and hyperornithinemia. Current therapeutic modalities potentially slow disease progression but are not successful in preventing blindness. To allow for trial development, increased knowledge of the clinical phenotype and current therapeutic outcomes is required.

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Retinitis pigmentosa (RP) is a progressive inherited retinal dystrophy, characterized by the degeneration of photoreceptors, presenting as a rod-cone dystrophy. Approximately 20-30% of patients with RP also exhibit extra-ocular manifestations in the context of a syndrome. This manuscript discusses the broad spectrum of syndromes associated with RP, pathogenic mechanisms, clinical manifestations, differential diagnoses, clinical management approaches, and future perspectives.

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  • Paediatric Leigh syndrome (LS) is a severe neurodegenerative disorder caused by mutations in the NDUFS4 gene, which affects mitochondrial function, and currently has no effective treatments.
  • Researchers used whole-body Ndufs4 knockout (KO) mice to analyze differences in brain proteomes between these mice and wildtype mice, identifying variations across different brain regions.
  • Findings highlighted reduced levels of critical mitochondrial components in specific brain areas and suggested that attempts to stimulate certain metabolic pathways could be harmful, prompting the need for new therapeutic strategies for managing LS.
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Genetic diagnosis plays a crucial role in rare diseases, particularly with the increasing availability of emerging and accessible treatments. The International Rare Diseases Research Consortium (IRDiRC) has set its primary goal as: "Ensuring that all patients who present with a suspected rare disease receive a diagnosis within one year if their disorder is documented in the medical literature". Despite significant advances in genomic sequencing technologies, more than half of the patients with suspected Mendelian disorders remain undiagnosed.

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Introduction: Rare genetic neurodevelopmental disorders and intellectual disability (ID), collectively called genetic ID (GID), can profoundly impact daily functioning and overall well-being of affected individuals. To improve our understanding of the impact of GID and advancing both care and research, measuring relevant patient reported outcomes (PROs) is crucial. Currently, various PROs are measured for GID.

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Background: Advances in understanding the etiology of intellectual disability (ID) has led to insights in potential (targeted) treatments and personalized care. Implications of ID on health are often complex and require a multidisciplinary approach. The aim was to investigate the reporting of genetic diagnoses in multidisciplinary ID care and to identify associated clinical and demographic factors.

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Rett syndrome (RTT) and Rett-like syndromes [i.e., CDKL5 deficiency disorder (CDD) and FOXG1-syndrome] represent rare yet profoundly impactful neurodevelopmental disorders (NDDs).

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  • Children with chronic conditions often have unique health care needs that may not be fully addressed through current treatment practices focused on family and patient preferences.
  • A scoping review was conducted to analyze interventions aimed at enhancing family-centered care for these children by examining relevant studies published between January 2019 and August 2020.
  • The review found 61 interventions, primarily using quasiexperimental and randomized controlled trial designs, with key focuses on improving communication, involving families in care decisions, and increasing access to health services.
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  • - Gyrate atrophy of the choroid and retina (GACR) is a genetic disorder linked to mutations in the OAT gene, leading to severe vision loss and high ornithine levels due to impaired enzyme function.
  • - The study identified 14 pathogenic variants in the OAT gene, with a specific mutation (p.(Gly353Asp)) found in all Dutch patients, which was shown to result in enzyme dysfunction and prevent effective pyridoxine treatment.
  • - Researchers developed a new diagnostic approach that includes enzymatic analysis of OAT and pyridoxine response tests to improve understanding of GACR and aid in managing patient expectations regarding treatment outcomes.
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ALDH7A1 encodes for the enzyme catalyzing the third step of the lysine degradation pathway. Biallelic pathogenic variants in ALDH7A1 are associated with pyridoxine dependent epilepsy (PDE), of which the c.1279G>C (p.

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GCDH encodes for the enzyme catalyzing the sixth step of the lysine degradation pathway. Autosomal recessive variants in GCDH are associated with glutaric aciduria type I (GA1), of which a wide genotypic spectrum of pathogenic variants have been described. In this study, hiPSC lines derived from four GA1 patients with different genotypes were generated and fully characterized.

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The Repeat Expansion Diseases (REDs) arise from the expansion of a disease-specific short tandem repeat (STR). Different REDs differ with respect to the repeat involved, the cells that are most expansion prone and the extent of expansion. Furthermore, whether these diseases share a common expansion mechanism is unclear.

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  • The International Rare Diseases Research Consortium (IRDiRC) Diagnostic Scientific Committee (DSC) focuses on improving diagnosis for rare diseases through global coordination and research.
  • Their goals include ensuring timely diagnoses, establishing effective diagnostic pathways, and evaluating how rare diseases impact patients.
  • The DSC has compiled research priorities and shared real-life clinical cases to highlight existing diagnostic challenges and underscore the importance of their mission.
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  • Gyrate atrophy of the choroid and retina (GACR) is a genetic disorder that causes progressive eye degeneration and significant vision loss, highlighting the importance of understanding its clinical characteristics for future treatments.
  • A study of 19 patients showed an early onset of eye symptoms, with many requiring cataract surgery by their late twenties, and demonstrated a link between early dietary protein restriction and improved outcomes in some cases.
  • The findings stress the severe nature of GACR, including complications like severe myopia and cystoid maculopathy, underlining the need for early diagnosis to facilitate timely interventions and improve patient quality of life.
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Pyridoxine-dependent epilepsy (PDE-ALDH7A1) is a neurometabolic disorder in the lysine metabolism pathway. In 2014 and 2021, the International PDE consortium published consensus guidelines about diagnosis and management. In this follow-on, a literature review was performed and nutrition management was evaluated through an international dietary questionnaire with 40 respondents.

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Objective: Hospital-to-home (H2H) transitions challenge families of children with medical complexity (CMC) and healthcare professionals (HCP). This study aimed to gain deeper insights into the H2H transition process and to work towards eHealth interventions for its improvement, by applying an iterative methodology involving both CMC families and HCP as end-users.

Methods: For 20-weeks, the Dutch Transitional Care Unit consortium collaborated with the Amsterdam University of Applied Sciences, HCP, and CMC families.

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Purpose: The functionality of many cellular proteins depends on cofactors; yet, they have only been implicated in a minority of Mendelian diseases. Here, we describe the first 2 inherited disorders of the cytosolic iron-sulfur protein assembly system.

Methods: Genetic testing via genome sequencing was applied to identify the underlying disease cause in 3 patients with microcephaly, congenital brain malformations, progressive developmental and neurologic impairments, recurrent infections, and a fatal outcome.

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  • - Volanesorsen is an RNA therapy that has shown effectiveness in reducing triglyceride (TG) levels in a 13-year-old girl with lipoprotein lipase (LPL) deficiency, a rare disorder that can lead to severe complications like pancreatitis.
  • - The study observed that after starting weekly injections of Volanesorsen, TG levels dropped significantly, with no hospitalizations for pancreatitis in the first 14 months, unlike the patient's previous 21 admissions over a similar timeframe.
  • - The treatment was well-tolerated, highlighting an improved quality of life for both the patient and her family, and suggesting the need for broader access to Volanesorsen for pediatric patients with LPL deficiency.
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The Repeat Expansion Diseases (REDs) arise from the expansion of a disease-specific short tandem repeat (STR). Different REDs differ with respect to the repeat involved, the cells that are most expansion prone and the extent of expansion. Furthermore, whether these diseases share a common expansion mechanism is unclear.

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Background: Generating rigorous evidence to inform care for rare diseases requires reliable, sustainable, and longitudinal measurement of priority outcomes. Having developed a core outcome set for pediatric medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, we aimed to assess the feasibility of prospective measurement of these core outcomes during routine metabolic clinic visits.

Methods: We used existing cohort data abstracted from charts of 124 children diagnosed with MCAD deficiency who participated in a Canadian study which collected data from birth to a maximum of 11 years of age to investigate the frequency of clinic visits and quality of metabolic chart data for selected outcomes.

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Purpose: To determine real-world diagnostic rates, cost trajectories, and cost-effectiveness of exome sequencing (ES) and genome sequencing (GS) for children with developmental and/or seizure disorders in British Columbia, Canada.

Methods: Based on medical records review, we estimated real-world costs and outcomes for 491 patients who underwent standard of care (SOC) diagnostic testing at British Columbia Children's Hospital. Results informed a state-transition Markov model examining cost-effectiveness of 3 competing diagnostic strategies: (1) SOC with last-tier access to ES, (2) streamlined ES access, and (3) first-tier GS.

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