Advances in technology, methodology, and deep phenotyping are increasingly driving the understanding of the pathologic basis of disease. Improvements in patient identification and treatment are ...impacting survival. This is true in endocrinology and inborn errors of metabolism, where disease-modifying therapies are developing. Inherent to this evolution is the increasing awareness of the respiratory manifestations of these rare diseases. This review updates clinicians, stratifying diseases spirometerically; pulmonary hypertension and diseases with a predisposition to recurrent pulmonary infection are discussed. This division is artificial; many diseases have multiple pathologic effects on respiration. This review does not cover the impact of obesity.
Childhood onset motor neuron diseases or neuronopathies are a clinically heterogeneous group of disorders. A particularly severe subgroup first described in 1894, and subsequently called ...Brown-Vialetto-Van Laere syndrome, is characterized by progressive pontobulbar palsy, sensorineural hearing loss and respiratory insufficiency. There has been no treatment for this progressive neurodegenerative disorder, which leads to respiratory failure and usually death during childhood. We recently reported the identification of SLC52A2, encoding riboflavin transporter RFVT2, as a new causative gene for Brown-Vialetto-Van Laere syndrome. We used both exome and Sanger sequencing to identify SLC52A2 mutations in patients presenting with cranial neuropathies and sensorimotor neuropathy with or without respiratory insufficiency. We undertook clinical, neurophysiological and biochemical characterization of patients with mutations in SLC52A2, functionally analysed the most prevalent mutations and initiated a regimen of high-dose oral riboflavin. We identified 18 patients from 13 families with compound heterozygous or homozygous mutations in SLC52A2. Affected individuals share a core phenotype of rapidly progressive axonal sensorimotor neuropathy (manifesting with sensory ataxia, severe weakness of the upper limbs and axial muscles with distinctly preserved strength of the lower limbs), hearing loss, optic atrophy and respiratory insufficiency. We demonstrate that SLC52A2 mutations cause reduced riboflavin uptake and reduced riboflavin transporter protein expression, and we report the response to high-dose oral riboflavin therapy in patients with SLC52A2 mutations, including significant and sustained clinical and biochemical improvements in two patients and preliminary clinical response data in 13 patients with associated biochemical improvements in 10 patients. The clinical and biochemical responses of this SLC52A2-specific cohort suggest that riboflavin supplementation can ameliorate the progression of this neurodegenerative condition, particularly when initiated soon after the onset of symptoms.
Thoracolumbar kyphosis is a common indication for spinal surgery in children with Mucopolysaccharidosis. Functional outcome of spinal surgical intervention has never been published in patients with ...this rare disease. We present a cohort of patients with Mucopolysaccharidosis 1(Hurler syndrome) who underwent thoraco-lumbar spinal deformity correction and functional outcome assessed by pre-operative and post-operative gait analysis. This study represents the first attempt at presenting a functional assessment of surgical outcome in any Mucopolysaccharidosis subtype.
A retrospective analysis of prospectively collected data was carried out from 11 children diagnosed with this subtype of Mucopolysaccharidosis. All patients underwent thoracolumbar kyphosis correction between the years 2013 to 2016. Gait assessment was performed using GAITRite™ electronic walkway pre-operatively and post-operatively within 9 to 24 months from the index surgery. Walking distance, cadence and gait velocity were the three spatio-temporal parameters analysed. Wilcoxon signed rank test was used to analyse the data and P-Value ≤0.05 was deemed significant.
There was a statistically significant improvement in walking distance in 9 out of 11 patient post-operatively with a mean increase of 232.06 cms (P = 0.05). There was marginal improvement in cadence by 6.33 steps/min post-operatively (P-value 0.79). Gait velocity also showed a marginal increase by 8.73 cms/sec post-operatively (P-value 0.32).
The results of our study suggest that correction of thoracolumbar kyphosis in children with Mucopolysaccharidosis 1 resulted in a significant improvement of walking distance with a trend towards improved gait in the other parameters. Post-operative change in cadence was not statistically significant suggesting that physiological maturation of gait had minimal effect in the specified post-operative assessment timeframe. This study emphasizes that outcomes of spinal surgery in children with Mucopolysaccharidosis 1 should be determined by functional measures aiming to maintain or improve quality of life.
Gyrate atrophy of the choroid and retina is a rare autosomal recessive metabolic disorder caused by biallelic variants in the OAT gene, encoding the enzyme ornithine delta-aminotransferase. Impaired ...enzymatic activity leads to systemic hyperornithinaemia, which in turn underlies progressive chorioretinal degeneration. In this study, we describe the clinical and molecular findings in a cohort of individuals with gyrate atrophy. Study participants were recruited through a tertiary UK clinical ophthalmic genetic service. All cases had a biochemical and molecular diagnosis of gyrate atrophy. Retrospective phenotypic and biochemical data were collected using electronic healthcare records. 18 affected individuals from 12 families (8 male, 10 female) met the study inclusion criteria. The median age at diagnosis was 8 years (range 10 months - 33 years) and all cases had hyperornithinaemia (median: 800 micromoles/L; range: 458-1244 micromoles/L). Common features at presentation included high myopia (10/18) and nyctalopia (5/18). Ophthalmic findings were present in all study participants who were above the age of 6 years. One third of patients had co-existing macular oedema and two thirds developed pre-senile cataracts. Compliance with dietary modifications was suboptimal in most cases. A subset of participants had extraocular features including a trend towards reduced fat-free mass and developmental delay. Our findings highlight the importance of multidisciplinary care in families with gyrate atrophy. Secondary ophthalmic complications such as macular oedema and cataract formation are common. Management of affected individuals remains challenging due to the highly restrictive nature of the recommended diet and the limited evidence-base for current strategies.
Fabry disease is a rare, X-linked inherited lysosomal storage disorder, that manifests as a heterogeneous disease with renal, cardiac and nervous system involvement. The most common pain experienced ...by people with Fabry disease are episodes of neuropathic pain reported in up to 80% of classical hemizygous male patients and up to 65% of heterozygous female patients. No clear consensus exists within UK clinical practice for the assessment and management of pain in Fabry disease based on agreed clinical practice and clinical experience. Here we describe a modified Delphi initiative to establish expert consensus on management of pain in Fabry disease in the UK clinical setting.
Delphi panel members were identified based on their demonstrated expertise in managing adult or paediatric patients with Fabry disease in the UK and recruited by an independent third-party administrator. Ten expert panellists agreed to participate in two survey rounds, during which they remained anonymous to each other. Circulation of the questionnaires, and collection and processing of the panel's responses were conducted between September 2021 and December 2021. All questions required an answer.
The Delphi panel reached a consensus on 21 out of 41 aspects of pain assessment and management of pain in Fabry disease. These encompassed steps in the care pathway from the goals of therapy through to holistic support, including the use of gabapentin and carbamazepine as first-line analgesic medications for the treatment of neuropathic pain in Fabry disease, as well as the proactive management of symptoms of anxiety and/or depression associated with Fabry pain.
The consensus panel outcomes reported here have highlighted strengths in current UK clinical practice, along with unmet needs for further research and agreement. This consensus is intended to prompt the next steps towards developing clinical guidelines.
Wolman disease is a rare, lysosomal storage disorder in which biallelic variants in the LIPA gene result in reduced or complete lack of lysosomal acid lipase. The accumulation of the substrates; ...cholesterol esters and triglycerides, significantly impacts cellular function. Untreated patients die within the first 12 months of life. Clinically, patients present severely malnourished, with diarrhoea and hepatosplenomegaly, many have an inflammatory phenotype, including with hemophagocytic lymphohistiocytosis (HLH). Hematopoietic stem cell transplant (HCT) had been historically the only treatment available but has a high procedure-related mortality because of disease progression and disease-associated morbidities. More recently, enzyme replacement therapy (ERT) with dietary substrate reduction (DSR) has significantly improved patient survival. However, ERT is life long, expensive and its utility is limited by anti-drug antibodies (ADA) and the need for central venous access.
We describe five Wolman disease patients diagnosed in infancy that were treated at Royal Manchester Children's Hospital receiving ERT with DSR then HCT-multimodal therapy. In 3/5 an initial response to ERT was attenuated by ADA with associated clinical and laboratory features of deterioration. 1/5 developed anaphylaxis to ERT and the other patient died post HCT with ongoing HLH. All patients received allogeneic HCT. 4/5 patients are alive, and both disease phenotype and laboratory parameters are improved compared to when they were on ERT alone. The gastrointestinal symptoms are particularly improved after HCT, with reduced diarrhoea and vomiting. This allows gradual structured normalisation of diet with improved tolerance of dietary fat. Histologically there are reduced cholesterol clefts, fewer foamy macrophages and an improved villous structure. Disease biomarkers also show improvement with ERT, immunotherapy and HCT. Three patients have mixed chimerism after HCT, indicating a likely engraftment-defect in this condition.
We describe combined ERT, DSR and HCT, multimodal treatment for Wolman disease. ERT and DSR stabilises the sick infant and reduces the formerly described prohibitively high, transplant-associated mortality in this condition. HCT abrogates the problems of ERT, namely attenuating ADA, the need for continuing venous access, and continuing high cost drug treatment. HCT also brings improved efficacy, particularly evident in improved gastrointestinal function and histology. Multimodal therapy should be considered a new paradigm of treatment for Wolman disease patients where there is an attenuated response to ERT, and for all patients where there is a well-matched transplant donor, in order to improve long term gut function, tolerance of a normal diet and quality of life.
Studies indicate that doses of alglucosidase alfa (ALGLU) higher than label dose (20 mg/kg every other week) improve clinical outcomes in infantile-onset Pompe disease (IOPD). We investigated data ...from the Pompe Registry to determine the association between ALGLU dose and survival in IOPD.
We included 332 IOPD patients from the Registry as of January 2022 who had cardiomyopathy and were first treated at age < 1 year. We used Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between ALGLU as a time-varying exposure and survival, adjusting for age at first treatment, sex, and cross-reactive immunologic material (CRIM)/immune tolerance induction (ITI) status. Dose was measured as average relative dose received over time (in multiples of label dose, range > 0 to 4 times label dose), current dose, and lagged dose. 81% patients received label dose at treatment initiation. Over time, 52% received a higher dose. Higher ALGLU dose over time was associated with improved survival: adjusted HR 0.40 (95% CI 0.22-0.73, p = 0.003) per 1-unit increase in average relative dose, with similar results for invasive ventilation-free survival (adjusted HR 0.48, 95% CI 0.28-0.84; p = 0.010). The association was consistent in patients first treated before or after 3 months of age and did not vary significantly by CRIM status. Results for current and lagged dose were similar to average dose.
Higher ALGLU doses were associated with significantly improved overall and invasive ventilator-free survival in IOPD. Results were consistent across sensitivity analyses.
Mucopolysaccharidosis type I (MPS I) is an inherited lysosomal storage disease. Affected individuals have disease ranging from attenuated to severe with significant disease burden, disability, and ...premature death. Early treatment with enzyme replacement therapy and/or stem cell transplantation can reduce disease progression and improve outcomes. However, diagnosis is often delayed, particularly for patients with attenuated phenotypes. We conducted a survey of 168 patients and 582 physicians to explore health care seeking patterns and familiarity of physicians with MPS I symptoms. Patients with attenuated MPS I typically first presented with stiff joints or hernia/bulging abdomen, and patients with severe disease with noisy/difficult breathing, or hernia/bulging abdomen. There was a mean delay from time of symptom presentation to diagnosis of 2.7years for patients with attenuated disease, with a mean of 5 physicians consulted before receiving a correct diagnosis. MPS I was most commonly misidentified by physicians as rheumatoid arthritis (48–72%), with a wide variety of suspected diseases, including lupus. CONCLUSION: Patient and physician real-world surveys show that MPS I is under-recognized and diagnosis of MPS I remains delayed, particularly in patients with attenuated disease. Across regions and specialties, physicians require differential diagnosis education in order to improve early detection and early treatment initiation of MPS I.
Objectives
This UK-wide study defines the natural history of argininosuccinic aciduria and compares long-term neurological outcomes in patients presenting clinically or treated prospectively from ...birth with ammonia-lowering drugs.
Methods
Retrospective analysis of medical records prior to March 2013, then prospective analysis until December 2015. Blinded review of brain MRIs.
ASL
genotyping.
Results
Fifty-six patients were defined as early-onset (
n
= 23) if symptomatic < 28 days of age, late-onset (
n
= 23) if symptomatic later, or selectively screened perinatally due to a familial proband (
n
= 10). The median follow-up was 12.4 years (range 0–53). Long-term outcomes in all groups showed a similar neurological phenotype including developmental delay (48/52), epilepsy (24/52), ataxia (9/52), myopathy-like symptoms (6/52) and abnormal neuroimaging (12/21). Neuroimaging findings included parenchymal infarcts (4/21), focal white matter hyperintensity (4/21), cortical or cerebral atrophy (4/21), nodular heterotopia (2/21) and reduced creatine levels in white matter (4/4). 4/21 adult patients went to mainstream school without the need of additional educational support and 1/21 lives independently. Early-onset patients had more severe involvement of visceral organs including liver, kidney and gut. All early-onset and half of late-onset patients presented with hyperammonaemia. Screened patients had normal ammonia at birth and received treatment preventing severe hyperammonaemia.
ASL
was sequenced (
n
= 19) and 20 mutations were found. Plasma argininosuccinate was higher in early-onset compared to late-onset patients.
Conclusions
Our study further defines the natural history of argininosuccinic aciduria and genotype–phenotype correlations. The neurological phenotype does not correlate with the severity of hyperammonaemia and plasma argininosuccinic acid levels. The disturbance in nitric oxide synthesis may be a contributor to the neurological disease. Clinical trials providing nitric oxide to the brain merit consideration.
The number of children on long-term ventilation (LTV) has exponentially increased over the past few decades. Improvements in management of ventilation coupled with improvements in standards of ...medical care are increasingly allowing young people on LTV to survive into adulthood. The process of transition from the pediatric to the adult healthcare system is challenging and requires special attention.
This review aims to provide an overview on transition to adult care for children on LTV. Firstly, examining effective models of transition in other childhood onset chronic conditions as a template, whilst highlighting the unique aspects of transition in LTV patients and secondly, summarizing the main relevant findings in the literature on the topic and emphasizing the importance of a multidisciplinary approach to this process.
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