Mortality in patients with alpha-mannosidosis: a review of patients' data and the literature

Monitoring and integrated care coordination of patients with alpha-mannosidosis: A global Delphi consensus study

INTRODUCTION

Current literature lacks consensus on initial assessments and routine follow-up care of patients with alpha-mannosidosis (AM). A Delphi panel was conducted to generate and validate recommendations on best practices for initial assessment, routine follow-up care, and integrated care coordination of patients with AM.

METHODS

A modified Delphi method involving 3 rounds of online surveys was used. An independent administrator and 2 nonvoting physician co-chairs managed survey development, anonymous data collection, and analysis. A multidisciplinary panel comprising 20 physicians from 12 countries responded to 57 open-ended questions in the first survey. Round 2 consisted of 11 ranking questions and 44 voting statements. In round 3, panelists voted to validate 60 consensus statements. The panel response rate was ≥95% in all 3 rounds. Panelists used 5-point Likert scales to indicate importance (score of ≥3) or agreement (score of ≥4). Consensus was defined a priori as ≥75% agreement with ≥75% of panelists voting.

RESULTS

Consensus was reached on 60 statements, encompassing 3 key areas: initial assessments, routine follow-up care, and treatment-related follow-up. The panel agreed on the type and frequency of assessments related to genetic testing, baseline evaluations, quality of life, biochemical measures, affected body systems, treatment received, and integrated care coordination in patients with AM. Forty-nine statements reached 90% to 100% consensus, 8 statements reached 80% to 85% consensus, and 1 statement reached 75% consensus. Two statements each reached consensus on 15 baseline assessments to be conducted at the initial follow-up visit after diagnosis in pediatric and adult patients.

CONCLUSION

This is the first Delphi study providing internationally applicable, best-practice recommendations for monitoring patients with AM that may improve their care and well-being.

Diagnosis of alpha-Mannosidosis: Practical approaches to reducing diagnostic delays in this ultra-rare disease

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.

Long-term outcome of a cohort of Italian patients affected with alpha-Mannosidosis

Alpha-mannosidosis (MIM #248500) is an ultra-rare autosomal recessive lysosomal storage disease with multi-system involvement and a wide phenotypic spectrum. Information on long-term outcomes remains poor. We present the long-term outcomes (median, 19 years) of nine patients with alpha-mannosidosis, three females and six males, followed at a single center. The findings of the nine patients were collected from medical records and reported as mean ± SD or median, and range. The age of onset of the first symptoms ranged from 0-1 to 10 years. The diagnostic delay ranged from 2 to 22 years (median= 11 years). Coarse face, hearing, heart valves, joints, gait, language, dysarthria, psychiatric symptoms, I.Q., MRI, walking disabilities, orthopedic disturbances and surgeries showed a slow worsening over the decades. Our patients showed a slowly worsening progressive outcome over the decades. Psychiatric symptoms were present in 100% of our population and improved with the appropriate pharmacological intervention. This aspect requires attention when following up on these patients. Our description of the long-term evolution of alpha-mannosidosis patients may provide basic knowledge for understanding the effects of specific treatments.

Estimating mortality in rare diseases using a population-based registry, 2002 through 2019

BACKGROUND

Rare diseases (RD) are a heterogeneous group of diseases, sharing aspects of complexity. Prognosis is variable, even in individuals with the same disease. Real-world data on RD as a whole are scarce. The aim of this study is to provide data on mortality and survival for a substantial group of RD deriving from a population-based registry, which covers the Veneto region in Italy (4.9 million inhabitants).

RESULTS

During the study period, 3367 deaths occurred, mainly in males (53.9%), elderly patients (63.5%) and patients with diseases having a reported prevalence of 1-9/100000 (65.6%). When standardizing by age, the mortality ratio was higher in RD patients than in the general population, SMR = 1.93 (95% CI 1.84-2.11), with an observed gender difference, 2.01 (95% CI 1.88-2.29) in females and 1.86 (95% CI 1.73-2.10) in males. The lowest survival rates are experienced by patients with rare neurologic diseases, rare skin diseases and rare systemic or rheumatologic diseases, 58%, 68% and 81%, respectively, after a 15-year observation period. It should be noted that only 18% of patients diagnosed with motor neuron diseases were alive after 15 years from diagnosis.

CONCLUSIONS

Despite progress in diagnosis, treatment and care in recent years, RD patients globally have higher mortality rates and reduced survival compared to the general population, with specific variations according to gender, age and disease group.

Global Proteomics for Identifying the Alteration Pathway of Niemann-Pick Disease Type C Using Hepatic Cell Models

Niemann-Pick disease type C (NPC) is an autosomal recessive disorder with progressive neurodegeneration. Although the causative genes were previously identified, NPC has unclear pathophysiological aspects, and patients with NPC present various symptoms and onset ages. However, various novel biomarkers and metabolic alterations have been investigated; at present, few comprehensive proteomic alterations have been reported in relation to NPC. In this study, we aimed to elucidate proteomic alterations in NPC and perform a global proteomics analysis for NPC model cells. First, we developed two NPC cell models by knocking out NPC1 using CRISPR/Cas9 (KO1 and KO2). Second, we performed a label-free (LF) global proteomics analysis. Using the LF approach, more than 300 proteins, defined as differentially expressed proteins (DEPs), changed in the KO1 and/or KO2 cells, while the two models shared 35 DEPs. As a bioinformatics analysis, the construction of a protein-protein interaction (PPI) network and an enrichment analysis showed that common characteristic pathways such as ferroptosis and mitophagy were identified in the two model cells. There are few reports of the involvement of NPC in ferroptosis, and this study presents ferroptosis as an altered pathway in NPC. On the other hand, many other pathways and DEPs were previously suggested to be associated with NPC, supporting the link between the proteome analyzed here and NPC. Therapeutic research based on these results is expected in the future.

Alfa-mannosidosis: Frequent Symptoms in Rare Patient

Background. Alfa-mannosidosis is ultra-rare autosomal recessive lysosomal storage disease caused by the mutation in the MAN2B1 gene. Pathogenic nucleotide variants and structural changes in this gene lead to acid alpha-mannosidase deficiency, this enzyme is involved in oligosaccharides degradation. This disease is characterized by multisystem involvement and chronic progressive course. Clinical case description. The clinical case attracted our attention due to the late disease diagnosis in a boy living in a metropolis. The child has classic clinical manifestations of the disease: typical phenotype, spinal deformity, developmental speech and motor delays, hearing loss, hepatomegaly, splenomegaly, umbilical and inguinal hernias. Despite developmental speech delay and frequent recurrent otitis, the patient has not been referred to surdologist examination until the age of 4.5 years. Intriguing fact is the presence of congenital cataract that was the reason for surgery twice. Conclusion. Congenital cataract is one of the early manifestation of this disease. 3 out of 8 patients with alfa-mannosidosis observed in our centre had congenital cataract. We assume that such patients should be referred to genetics for the early exclusion of alpha-mannosidosis. Late diagnosis and progressive course of the disease led to early disability of the patient. Nowadays, as enzyme replacement therapy is available, it is crucial to identify these patients timely in order to improve their quality of life and increase survivability.

Die α-Mannosidose: eine seltene, aber unterdiagnostizierte Erkrankung?

Bei der α‑Mannosidose handelt es sich um eine seltene lysosomale Speichererkrankung, bedingt durch eine autosomal-rezessiv vererbte Defizienz der α‑Mannosidase. Die Erkrankung weist ein breites klinisches Spektrum mit chronisch progredientem Verlauf auf. Charakteristische klinische Zeichen in den ersten Lebensjahren sind Hörminderung, Entwicklungsverzögerung, rezidivierende Infekte und/oder faziale Dysmorphie. Im weiteren Verlauf der Erkrankung manifestieren sich zunehmende skeletale Probleme und eine Ataxie, beide zu Immobilität führend. Im Gegensatz zu anderen lysosomalen Speichererkrankungen zeigt sich nach dem 20. Lebensjahr meist kein weiterer Verlust kognitiver Fähigkeiten. Ab dem Alter von 15 Jahren entwickeln ca. 25 % der Patienten psychiatrische Symptome. Aufgrund der Seltenheit der Erkrankung werden viele Patienten verspätet, z. T. erst im Erwachsenenalter, diagnostiziert.

Mittlerweile stehen 2 Therapieoptionen zur Behandlung der α‑Mannosidose zur Verfügung. Bei frühzeitiger Diagnosestellung ist die hämatopoetische Stammzelltransplantation eine wichtige therapeutische Option mit potenziell positivem Effekt auf die neurokognitive Entwicklung. Die Enzymersatztherapie mit Velmanase alfa ist seit 2018 in Europa zugelassen und eine therapeutische Option zur Behandlung der nichtneurologischen Manifestationen bei α‑Mannosidose. Sie hat jedoch keinen Einfluss auf neurologische Manifestationen der Erkrankung.

Zur Verbesserung der Diagnostik von Kindern und Jugendlichen mit der seltenen Erkrankung α‑Mannosidose möchte dieser Beitrag das Wissen um und das Bewusstsein für diese Erkrankung schärfen. Die frühe Diagnose einer α‑Mannosidose erspart nicht nur den Familien einen jahrelangen diagnostischen Leidensweg, sondern ermöglicht auch den betroffenen Patienten ein verbessertes Auskommen durch einen frühen Therapiestart.