Am J Hum Genet. 2024 Mar 27:S0002-9297(24)00081-8. doi: 10.1016/j.ajhg.2024.03.008. Online ahead of print.

ABSTRACT

Copy number variants (CNVs) are significant contributors to the pathogenicity of rare genetic diseases and, with new innovative methods, can now reliably be identified from exome sequencing. Challenges still remain in accurate classification of CNV pathogenicity. CNV calling using GATK-gCNV was performed on exomes from a cohort of 6,633 families (15,759 individuals) with heterogeneous phenotypes and variable prior genetic testing collected at the Broad Institute Center for Mendelian Genomics of the Genomics Research to Elucidate the Genetics of Rare Diseases consortium and analyzed using the seqr platform. The addition of CNV detection to exome analysis identified causal CNVs for 171 families (2.6%). The estimated sizes of CNVs ranged from 293 bp to 80 Mb. The causal CNVs consisted of 140 deletions, 15 duplications, 3 suspected complex structural variants (SVs), 3 insertions, and 10 complex SVs, the latter two groups being identified by orthogonal confirmation methods. To classify CNV variant pathogenicity, we used the 2020 American College of Medical Genetics and Genomics/ClinGen CNV interpretation standards and developed additional criteria to evaluate allelic and functional data as well as variants on the X chromosome to further advance the framework. We interpreted 151 CNVs as likely pathogenic/pathogenic and 20 CNVs as high-interest variants of uncertain significance. Calling CNVs from existing exome data increases the diagnostic yield for individuals undiagnosed after standard testing approaches, providing a higher-resolution alternative to arrays at a fraction of the cost of genome sequencing. Our improvements to the classification approach advances the systematic framework to assess the pathogenicity of CNVs.

PMID:38565148 | DOI:10.1016/j.ajhg.2024.03.008

Pharmacoepidemiol Drug Saf. 2024 Apr;33(4):e5778. doi: 10.1002/pds.5778.

ABSTRACT

PURPOSE: In rare diseases, real-world evidence (RWE) generation is often restricted due to small patient numbers and global geographic distribution. A federated data network (FDN) approach brings together multiple data sources harmonized for collaboration to increase the power of observational research. In this paper, we review how to increase reproducibility and transparency of RWE studies in rare diseases through disease-specific FDNs.

METHOD: To be successful, a multiple stakeholder scientific FDN collaboration requires a strong governance model in place. In such a model, each database owner remains in full control regarding the use of and access to patient-level data and is responsible for data privacy, ethical, and legal compliance. Provided that all this is well documented and good database descriptions are in place, such a governance model results in increased transparency, while reproducibility is achieved through data curation and harmonization, and distributed analytical methods.

RESULTS: Leveraging the OHDSI community set of methods and tools, two rare disease-specific FDNs are discussed in more detail. For multiple myeloma, HONEUR-the Haematology Outcomes Network in Europe-has built a strong community among the data partners dedicated to scientific exchange and research. To advance scientific knowledge in pulmonary hypertension (PH) an FDN, called PHederation, was established to form a partnership of research institutions with PH databases coming from diverse origins.

PMID:38556812 | DOI:10.1002/pds.5778

Mol Genet Metab. 2024 May;142(1):108444. doi: 10.1016/j.ymgme.2024.108444. Epub 2024 Mar 14.

ABSTRACT

Alpha-mannosidosis is an ultra-rare lysosomal disease that is caused by variants of the MAN2B1 gene on chromosome 19p13. These variants result in faulty or absent alpha-mannosidase in lysosomes, which leads to intracellular accumulation of mannose-containing oligosaccharides. Diagnosis of alpha-mannosidosis is often delayed, in part because of the rarity of the disease, its gradual onset and heterogeneity of presentation, but also because of the similarity of many signs and symptoms of the disease to those of other lysosomal diseases. Treatment of alpha-mannosidosis was previously limited to hematopoietic stem cell transplantation, but outcomes are variable and not all patients are eligible or have a suitable donor. Recently, an enzyme replacement therapy, recombinant human alpha-mannosidase (velmanase alfa), was approved for the treatment of non-neurological manifestations in adult and pediatric patients with alpha-mannosidosis. Treatment with velmanase alfa reduces serum levels of oligosaccharides, increases levels of immunoglobulin G, and improves patients' functional capacity and quality of life, although it is not effective for the neurologic phenotype because it does not cross the blood-brain barrier. Since the effects of velmanase alfa are more marked in children than adults, early diagnosis to allow early initiation of treatment has become more important. To support this, patient, parent/caregiver, and clinician awareness and education is imperative. A number of approaches can be taken to meet this goal, such as the development of disease registries, validated diagnostic algorithms, and screening tools, improved under-/post-graduate clinician education, easily accessible and reliable information for patients/families (such as that made available on the internet), and the formation of patient advocacy groups. Such approaches may raise awareness of alpha-mannosidosis, reduce the diagnostic delay and thus improve the lives of those affected.

PMID:38555683 | DOI:10.1016/j.ymgme.2024.108444

J Endocrinol Invest. 2024 Apr 1. doi: 10.1007/s40618-024-02365-8. Online ahead of print.

ABSTRACT

PURPOSE: Gorham-Stout disease is a very rare disorder characterized by progressive bone erosion and angiomatous proliferation; its etiopathogenesis is still unknown, and diagnosis is still performed by exclusion criteria. The alteration of bone remodeling activity has been reported in patients; in this study, we characterized circulating osteoclast and osteogenic precursors that could be important to better understand the osteolysis observed in patients.

METHODS: Flow cytometry analysis of PBMC (Peripheral Blood Mononuclear Cells) was performed to characterize circulating osteoclast and osteogenic precursors in GSD patients (n = 9) compared to healthy donors (n = 55). Moreover, ELISA assays were assessed to evaluate serum levels of bone markers including RANK-L (Receptor activator of NF-κB ligand), OPG (Osteoprotegerin), BALP (Bone Alkaline Phosphatase) and OCN (Osteocalcin).

RESULTS: We found an increase of CD16-/CD14+CD11b+ and CD115+/CD14+CD11b+ osteoclast precursors in GSD patients, with high levels of serum RANK-L that could reflect the increase of bone resorption activity observed in patients. Moreover, no significant alterations were found regarding osteogenic precursors and serum levels of BALP and OCN.

CONCLUSION: The analysis of circulating bone cell precursors, as well as of RANK-L, could be relevant as an additional diagnostic tool for these patients and could be exploited for therapeutic purposes.

PMID:38556572 | DOI:10.1007/s40618-024-02365-8

Front Endocrinol (Lausanne). 2024 Mar 13;15:1345067. doi: 10.3389/fendo.2024.1345067. eCollection 2024.

ABSTRACT

BACKGROUND: Mandibuloacral dysplasia (MAD) syndrome is a rare genetic disease. Several progeroid syndromes including mandibuloacral dysplasia type A (MADA), mandibuloacral dysplasia type B(MADB), Hutchinson-Gilford progeria (HGPS) and mandibular hypoplasia, deafness, and lipodystrophy syndrome (MDPL) have been reported previously. A novel MAD progeroid syndrome (MADaM) has recently been reported. So far, 7 cases of MADaM diagnosed with molecular diagnostics have been reported in worldwide. In the Chinese population, cases of MAD associated with the MTX2 variant have never been reported.

METHODS: The clinical symptoms and the genetic analysis were identified and investigated in patients presented with the disease. In addition, we analyzed and compared 7 MADaM cases reported worldwide and summarized the progeroid syndromes reported in the Chinese population to date.

RESULTS: The present study reports a case of a novel homozygous mutation c.378 + 1G > A in the MTX2 gene, which has not been previously reported in the literature. Patients present with early onset and severe symptoms and soon after birth are found to have growth retardation. In addition to the progeroid features, skeletal deformities, generalized lipodystrophy reported previously, and other multisystem involvement, e.g. hepatosplenic, renal, and cardiovascular system, this case was also reported to have combined hypogammaglobulinemia. She has since been admitted to the hospital several times for infections. Among 22 previously reported progeroid syndromes, 16/22 were MADA or HGPS caused by LMNA gene mutations, and the homozygous c.1579C > T (p.R527C) mutation may be a hot spot mutation for MAD in the Chinese population. MAD and HGPS mostly present in infancy with skin abnormalities or alopecia, MDPL mostly presents in school age with growth retardation as the first manifestation, and is often combined with an endocrine metabolism disorder after several decades.

CONCLUSION: This is the first case of MAD syndrome caused by mutations in MTX2 gene reported in the Chinese population. MTX2 gene c.378 + 1G > A homozygous mutation has not been previously reported and the report of this patient expands the spectrum of MTX2 mutations. In addition, we summarized the genotypes and clinical characteristics of patients with progeroid syndromes in China.

PMID:38544690 | PMC:PMC10965776 | DOI:10.3389/fendo.2024.1345067

Genes (Basel). 2024 Mar 17;15(3):370. doi: 10.3390/genes15030370.

ABSTRACT

Genomic variant prioritization is crucial for identifying disease-associated genetic variations. Integrating facial and clinical feature analyses into this process enhances performance. This study demonstrates the integration of facial analysis (GestaltMatcher) and Human Phenotype Ontology analysis (CADA) within VarFish, an open-source variant analysis framework. Challenges related to non-open-source components were addressed by providing an open-source version of GestaltMatcher, facilitating on-premise facial analysis to address data privacy concerns. Performance evaluation on 163 patients recruited from a German multi-center study of rare diseases showed PEDIA's superior accuracy in variant prioritization compared to individual scores. This study highlights the importance of further benchmarking and future integration of advanced facial analysis approaches aligned with ACMG guidelines to enhance variant classification.

PMID:38540429 | DOI:10.3390/genes15030370

Biomolecules. 2024 Mar 14;14(3):349. doi: 10.3390/biom14030349.

ABSTRACT

Heterotopic ossification (HO) is a debilitating pathology where ectopic bone develops in areas of soft tissue. HO can develop as a consequence of traumatic insult or as a result of dysregulated osteogenic signaling, as in the case of the orphan disease fibrodysplasia ossificans progressiva (FOP). Traumatic HO (tHO) formation is mediated by the complex interplay of signaling between progenitor, inflammatory, and nerve cells, among others, making it a challenging process to understand. Research into the pathogenesis of genetically mediated HO (gHO) in FOP has established a pathway involving uninhibited activin-like kinase 2 receptor (ALK2) signaling that leads to downstream osteogenesis. Current methods of diagnosis and treatment lag behind pre-mature HO detection and progressive HO accumulation, resulting in irreversible decreases in range of motion and chronic pain for patients. As such, it is necessary to draw on advancements made in the study of tHO and gHO to better diagnose, comprehend, prevent, and treat both.

PMID:38540768 | DOI:10.3390/biom14030349

S Afr Med J. 2023 Dec 4;113(12):9. doi: 10.7196/SAMJ.2023.v113i12.1507.

NO ABSTRACT

PMID:38525623 | DOI:10.7196/SAMJ.2023.v113i12.1507

Reumatismo. 2024 Mar 22;76(1). doi: 10.4081/reumatismo.2024.1621.

ABSTRACT

OBJECTIVE: Melorheostosis is a rare, non-hereditary, benign bone disease characterized by abnormal bone growth. Generally, melorheostosis develops during childhood or adolescence and progresses gradually over time. This disease represents a true challenge to the physician because of its variability due to location, extension of the affected bone, and involvement of associated soft tissue. Pain management, physical therapy, and surgery may be recommended, depending on the individual case. This review aims to get an overview of the latest evidence relating to epidemiology, clinical and radiographic characteristics, diagnosis, and possible therapeutic strategies for melorheostosis and describe our experience through a clinical case.

METHODS: We designed a comprehensive literature search on melorheostosis in MEDLINE (via Pubmed) up to April 2023 and reviewed reports published in international journals.

RESULTS: The purpose is to highlight the importance of a multidisciplinary approach in the management of a rare disease such as melorheostosis. We discuss the role of different physicians, including genetists, rheumatologists, physiatrists, physical therapists, and orthopedic surgeons, in providing accurate diagnoses and effective treatments. We conducted a comprehensive review of the literature on the treatment of melorheostosis to support these findings. In addition, the article presents a case study of a patient suffering from melorheostosis, focusing on difficulties in reaching a correct diagnosis and attempts towards conservative and surgical interventions. The patient underwent hip arthroplasty, and the final result was an improvement in function and a reduction in pain.

CONCLUSIONS: Managing melorheostosis can be challenging, and there is no standardized treatment for this condition at the moment.

PMID:38523583 | DOI:10.4081/reumatismo.2024.1621

Birth Defects Res. 2024 Mar;116(3):e2331. doi: 10.1002/bdr2.2331.

ABSTRACT

BACKGROUND: Human studies of genetic risk factors for neural tube defects, severe birth defects associated with long-term health consequences in surviving children, have predominantly been restricted to a subset of candidate genes in specific biological pathways including folate metabolism.

METHODS: In this study, we investigated the association of genetic variants spanning the genome with risk of spina bifida (i.e., myelomeningocele and meningocele) in a subset of families enrolled from December 2016 through December 2022 in a case-control study in Bangladesh, a population often underrepresented in genetic studies. Saliva DNA samples were analyzed using the Illumina Global Screening Array. We performed genetic association analyses to compare allele frequencies between 112 case and 121 control children, 272 mothers, and 128 trios.

RESULTS: In the transmission disequilibrium test analyses with trios only, we identified three novel exonic spina bifida risk loci, including rs140199800 (SULT1C2, p = 1.9 × 10-7), rs45580033 (ASB2, p = 4.2 × 10-10), and rs75426652 (LHPP, p = 7.2 × 10-14), after adjusting for multiple hypothesis testing. Association analyses comparing cases and controls, as well as models that included their mothers, did not identify genome-wide significant variants.

CONCLUSIONS: This study identified three novel single nucleotide polymorphisms involved in biological pathways not previously associated with neural tube defects. The study warrants replication in larger groups to validate findings and to inform targeted prevention strategies.

PMID:38526198 | DOI:10.1002/bdr2.2331

Mol Genet Metab. 2024 Mar 18;142(1):108453. doi: 10.1016/j.ymgme.2024.108453. Online ahead of print.

ABSTRACT

Growing interest in therapeutic development for rare diseases necessitate a systematic approach to the collection and curation of natural history data that can be applied consistently across this group of heterogenous rare diseases. In this study, we discuss the challenges facing natural history studies for leukodystrophies and detail a novel standardized approach to creating a longitudinal natural history study using existing medical records. Prospective studies are uniquely challenging for rare diseases. Delays in diagnosis and overall rarity limit the timely collection of natural history data. When feasible, prospective studies are often cross-sectional rather than longitudinal and are unlikely to capture pre- or early- symptomatic disease trajectories, limiting their utility in characterizing the full natural history of the disease. Therapeutic development in leukodystrophies is subject to these same obstacles. The Global Leukodystrophy Initiative Clinical Trials Network (GLIA-CTN) comprises of a network of research institutions across the United States, supported by a multi-center biorepository protocol, to map the longitudinal clinical course of disease across leukodystrophies. As part of GLIA-CTN, we developed Standard Operating Procedures (SOPs) that delineated all study processes related to staff training, source documentation, and data sharing. Additionally, the SOP detailed the standardized approach to data extraction including diagnosis, clinical presentation, and medical events, such as age at gastrostomy tube placement. The key variables for extraction were selected through face validity, and common electronic case report forms (eCRF) across leukodystrophies were created to collect analyzable data. To enhance the depth of the data, clinical notes are extracted into "original" and "imputed" encounters, with imputed encounter referring to a historic event (e.g., loss of ambulation 3 months prior). Retrospective Functional Assessments were assigned by child neurologists, using a blinded dual-rater approach and score discrepancies were adjudicated by a third rater. Upon completion of extraction, data source verification is performed. Data missingness was evaluated using statistics. The proposed methodology will enable us to leverage existing medical records to address the persistent gap in natural history data within this unique disease group, allow for assessment of clinical trajectory both pre- and post-formal diagnosis, and promote recruitment of larger cohorts.

PMID:38522179 | DOI:10.1016/j.ymgme.2024.108453

EMBO Mol Med. 2024 Mar 21. doi: 10.1038/s44321-024-00054-w. Online ahead of print.

ABSTRACT

Cereblon/CRBN is a substrate-recognition component of the Cullin4A-DDB1-Roc1 E3 ubiquitin ligase complex. Destabilizing mutations in the human CRBN gene cause a form of autosomal recessive non-syndromic intellectual disability (ARNSID) that is modelled by knocking-out the mouse Crbn gene. A reduction in excitatory neurotransmission has been proposed as an underlying mechanism of the disease. However, the precise factors eliciting this impairment remain mostly unknown. Here we report that CRBN molecules selectively located on glutamatergic neurons are necessary for proper memory function. Combining various in vivo approaches, we show that the cannabinoid CB1 receptor (CB1R), a key suppressor of synaptic transmission, is overactivated in CRBN deficiency-linked ARNSID mouse models, and that the memory deficits observed in these animals can be rescued by acute CB1R-selective pharmacological antagonism. Molecular studies demonstrated that CRBN interacts physically with CB1R and impairs the CB1R-Gi/o-cAMP-PKA pathway in a ubiquitin ligase-independent manner. Taken together, these findings unveil that CB1R overactivation is a driving mechanism of CRBN deficiency-linked ARNSID and anticipate that the antagonism of CB1R could constitute a new therapy for this orphan disease.

PMID:38514794 | DOI:10.1038/s44321-024-00054-w

Hum Genomics. 2024 Mar 21;18(1):28. doi: 10.1186/s40246-024-00595-8.

ABSTRACT

BACKGROUND: In the process of finding the causative variant of rare diseases, accurate assessment and prioritization of genetic variants is essential. Previous variant prioritization tools mainly depend on the in-silico prediction of the pathogenicity of variants, which results in low sensitivity and difficulty in interpreting the prioritization result. In this study, we propose an explainable algorithm for variant prioritization, named 3ASC, with higher sensitivity and ability to annotate evidence used for prioritization. 3ASC annotates each variant with the 28 criteria defined by the ACMG/AMP genome interpretation guidelines and features related to the clinical interpretation of the variants. The system can explain the result based on annotated evidence and feature contributions.

RESULTS: We trained various machine learning algorithms using in-house patient data. The performance of variant ranking was assessed using the recall rate of identifying causative variants in the top-ranked variants. The best practice model was a random forest classifier that showed top 1 recall of 85.6% and top 3 recall of 94.4%. The 3ASC annotates the ACMG/AMP criteria for each genetic variant of a patient so that clinical geneticists can interpret the result as in the CAGI6 SickKids challenge. In the challenge, 3ASC identified causal genes for 10 out of 14 patient cases, with evidence of decreased gene expression for 6 cases. Among them, two genes (HDAC8 and CASK) had decreased gene expression profiles confirmed by transcriptome data.

CONCLUSIONS: 3ASC can prioritize genetic variants with higher sensitivity compared to previous methods by integrating various features related to clinical interpretation, including features related to false positive risk such as quality control and disease inheritance pattern. The system allows interpretation of each variant based on the ACMG/AMP criteria and feature contribution assessed using explainable AI techniques.

PMID:38509596 | PMC:PMC10956189 | DOI:10.1186/s40246-024-00595-8

Int J Equity Health. 2024 Mar 19;23(1):64. doi: 10.1186/s12939-024-02137-z.

ABSTRACT

BACKGROUND: China has implemented policies to make rare diseases more affordable. While previous studies evaluated overall affordability, few have examined affordability differences across regions and disease types. Given the vastness of China and varying medical policies across cities, this study assesses the affordability of rare diseases based on China's First List of Rare Diseases (CFLRD), National Reimbursement Drug List (NRDL), and outpatient chronic and special disease policies in each prefecture.

METHOD: Six rare diseases were selected and the average annual treatment cost of all relevant drugs in NRDL was calculated for each disease. Based on the WHO/HAI standardized approach, the study analyzed 289 cities with outpatient chronic and special disease policies, measured the security levels by the actual reimbursement ratio of Basic Medical Insurance (BMI) and affordability by the ratio of individual expenses after reimbursement to the annual disposable income of urban residents in the province. The security levels and affordability differences across disease types and provinces were analyzed using the Mann-Whitney U test and the K-W test.

RESULT: The affordability of rare diseases varied significantly on the disease types and annual treatment cost. Diseases with an annual treatment cost below 100 000 yuan are affordable to all prefectures even with low reimbursement rates, while those with a higher treatment cost were not affordable in at least 80% of prefectures even though the reimbursement ratio is high. The affordability of the same disease varies significantly across provinces and municipalities. Outpatient chronic and special diseases insurance and critical illness insurance, and the inconsistencies between them, result in regional differences.

CONCLUSION: Although China has made progress in improving the affordability of rare diseases, significant differences persist between cities and diseases. The study suggests the optimization of the BMI system and explores independent funds and innovative insurance models to enhance the affordability of rare diseases, particularly those with extremely high treatment costs.

PMID:38504266 | PMC:PMC10953120 | DOI:10.1186/s12939-024-02137-z

Cell. 2024 Mar 11:S0092-8674(24)00227-7. doi: 10.1016/j.cell.2024.02.025. Online ahead of print.

ABSTRACT

Characterizing somatic mutations in the brain is important for disentangling the complex mechanisms of aging, yet little is known about mutational patterns in different brain cell types. Here, we performed whole-genome sequencing (WGS) of 86 single oligodendrocytes, 20 mixed glia, and 56 single neurons from neurotypical individuals spanning 0.4-104 years of age and identified >92,000 somatic single-nucleotide variants (sSNVs) and small insertions/deletions (indels). Although both cell types accumulate somatic mutations linearly with age, oligodendrocytes accumulated sSNVs 81% faster than neurons and indels 28% slower than neurons. Correlation of mutations with single-nucleus RNA profiles and chromatin accessibility from the same brains revealed that oligodendrocyte mutations are enriched in inactive genomic regions and are distributed across the genome similarly to mutations in brain cancers. In contrast, neuronal mutations are enriched in open, transcriptionally active chromatin. These stark differences suggest an assortment of active mutagenic processes in oligodendrocytes and neurons.

PMID:38503282 | DOI:10.1016/j.cell.2024.02.025

J Perinatol. 2024 Mar 18. doi: 10.1038/s41372-024-01935-1. Online ahead of print.

ABSTRACT

OBJECTIVE: To evaluate patterns of genetic testing among infants with CHD at a tertiary care center.

STUDY DESIGN: We conducted a retrospective observational cohort study of infants in the NICU with suspicion of a genetic disorder. 1075 of 7112 infants admitted to BCH had genetic evaluation including 329 with CHD and 746 without CHD. 284 of 525 infants with CHD admitted to CMHH had genetic evaluation. Patterns of testing and diagnoses were compared.

RESULTS: The rate of diagnosis after testing was similar for infants with or without CHD (38% [121/318] vs. 36% [246/676], p = 0.14). In a multiple logistic regression, atrioventricular septal defects were most high associated with genetic diagnosis (odds ratio 29.99, 95% confidence interval 2.69-334.12, p < 0.001).

CONCLUSIONS: Infants with suspicion of a genetic disorder with CHD had similar rates of molecular diagnosis as those without CHD. These results support a role for genetic testing among NICU infants with CHD.

PMID:38499751 | DOI:10.1038/s41372-024-01935-1

BMJ Case Rep. 2024 Mar 18;17(3):e256608. doi: 10.1136/bcr-2023-256608.

ABSTRACT

Ductal carcinoma in situ is very rare in male patients, accounting for approximately 5%-7% of all male breast cancers. We present a case of a man in his early 70s who presented with bloody nipple discharge and gynaecomastia and was subsequently diagnosed with ductal carcinoma in situ (DCIS). We discuss his management with surgical resection and the consideration of adjuvant treatment. We also review the existing literature on the presentation, diagnosis and management of DCIS in men.

PMID:38499353 | DOI:10.1136/bcr-2023-256608

Ann Child Neurol Soc. 2023 Sep;1(3):228-238. doi: 10.1002/cns3.20038. Epub 2023 Sep 12.

ABSTRACT

OBJECTIVE: To determine the longitudinal distribution of hand function skills in individuals with classic Rett Syndrome (RTT), an X-linked dominant neurodevelopmental disorder, and correlate with MECP2 variants.

METHOD: We conducted a longitudinal study of 946 girls and young women with typical RTT seen between 2006 and 2021 in the US Natural History Study (NHS) featuring a structured clinical evaluation to assess the level of hand function skills. The specific focus in this study was to assess longitudinal variation of hand skills from age 2 through age 18 years in relation to specific MECP2 variant groups.

RESULTS: Following the initial regression period, hand function continues to decline across the age spectrum in individuals with RTT. Specific differences are noted with steeper declines in hand function among those with milder variants (Group A: R133C, R294X, R306C, and C-terminal truncations) compared to groups composed of individuals with more severe variants.

CONCLUSIONS: These temporal variations in hand use represent specific considerations which could influence the design of clinical trials that test therapies aiming to ameliorate specific functional limitations in individuals with RTT. Furthermore, the distinct impact of specific MECP2 variants on clinical severity, especially related to hand use, should be considered in such interventional trials.

PMID:38496825 | PMC:PMC10939125 | DOI:10.1002/cns3.20038

Innov Clin Neurosci. 2024 Mar 1;21(1-3):52-60. eCollection 2024 Jan-Mar.

ABSTRACT

The 1983 Orphan Drug Act in the United States (US) changed the landscape for development of therapeutics for rare or orphan diseases, which collectively affect approximately 300 million people worldwide, half of whom are children. The act has undoubtedly accelerated drug development for orphan diseases, with over 6,400 orphan drug applications submitted to the US Food and Drug Administration (FDA) from 1983 to 2023, including 350 drugs approved for over 420 indications. Drug development in this population is a global and collaborative endeavor. This position paper of the International Society for Central Nervous System Clinical Trials and Methodology (ISCTM) describes some potential best practices for the involvement of key stakeholder feedback in the drug development process. Stakeholders include advocacy groups, patients and caregivers with lived experience, public and private research institutions (including academia and pharmaceutical companies), treating clinicians, and funders (including the government and independent foundations). The authors articulate the challenges of drug development in orphan diseases and propose methods to address them. Challenges range from the poor understanding of disease history to development of endpoints, targets, and clinical trials designs, to finding solutions to competing research priorities by involved parties.

PMID:38495603 | PMC:PMC10941866

Lancet. 2024 Mar 30;403(10433):1279-1289. doi: 10.1016/S0140-6736(23)02843-X. Epub 2024 Mar 13.

ABSTRACT

BACKGROUND: Individuals with rare kidney diseases account for 5-10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure.

METHODS: People aged 0-96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan-Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1·73 m2 or more to first eGFR of less than 30 mL/min per 1·73 m2 (the therapeutic trial window).

FINDINGS: Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9·6 years (IQR 5·9-16·7). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2·81 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<0·0001), but better survival rates (standardised mortality ratio 0·42 [95% CI 0·32-0·52]; p<0·0001). Median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, and therapeutic trial window all varied substantially between rare diseases.

INTERPRETATION: Patients with rare kidney diseases differ from the general population of individuals with chronic kidney disease: they have higher 5-year rates of kidney failure but higher survival than other patients with chronic kidney disease stages 3-5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on long-term kidney replacement therapy demand.

FUNDING: RaDaR is funded by the Medical Research Council, Kidney Research UK, Kidney Care UK, and the Polycystic Kidney Disease Charity.

PMID:38492578 | DOI:10.1016/S0140-6736(23)02843-X