-
Cureus Apr 2024Alpha-mannosidosis is a rare lysosomal storage disorder with progressive impairments in motor functions, skeletal deformities, and immunodeficiency. Enzyme replacement...
Prenatal Diagnosis of c.437-1G>A Mutation in the MAN2B1 Gene in a Family With Alpha-Mannosidosis: Unraveling Clinical Presentation and Treatment Outcomes in a Novel Prenatal Case.
Alpha-mannosidosis is a rare lysosomal storage disorder with progressive impairments in motor functions, skeletal deformities, and immunodeficiency. Enzyme replacement therapy (ERT) should be initiated early to achieve optimal outcomes. This report describes how alpha-mannosidosis diagnosis in a seven-year-old girl led to a successful prenatal diagnosis in the subsequent pregnancy and pre-symptomatic treatment at the early disease stage. The index patient was a seven-year-old girl who was referred with a confirmed diagnosis of alpha-mannosidosis based on the presence of homozygous c.437-1G>A mutation in the MAN2B1 gene. A prenatal diagnosis was made in the subsequent pregnancy through molecular analysis, which revealed the same homozygous variant. The patient was treated at the fifth week of age and showed mild skeletal involvement and normal development at ERT initiation. At 11 months of age, the ERT level increased to 15.8 µmol/l/h. The motor assessment showed that the patient was developmentally normal and was able to maintain her sitting and walking for a few steps only. Prenatal molecular screening in affected families can allow for the early identification and implementation of appropriate management strategies for alpha-mannosidosis.
PubMed: 38800253
DOI: 10.7759/cureus.58922 -
Molecular Genetics and Metabolism May 2024Alpha-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... (Review)
Review
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.
Topics: Humans; alpha-Mannosidosis; Enzyme Replacement Therapy; alpha-Mannosidase; Delayed Diagnosis; Rare Diseases
PubMed: 38555683
DOI: 10.1016/j.ymgme.2024.108444 -
European Journal of Medical Genetics Apr 2024Alpha mannosidosis is an autosomal recessive lysosomal storage disorder caused by biallelic pathogenic variants in the MAN2B1 gene. It manifests with clinical features,...
BACKGROUND
Alpha mannosidosis is an autosomal recessive lysosomal storage disorder caused by biallelic pathogenic variants in the MAN2B1 gene. It manifests with clinical features, including intellectual disability, hearing impairment, coarse facial appearance, skeletal anomalies, immunodeficiency, central nervous system involvement, psychiatric comorbidities, corneal opacity, and hepatosplenomegaly. This multicenter study assesses the long-term outcomes of individuals diagnosed with alpha-mannosidosis, examining demographic, clinical, laboratory, and molecular characteristics.
METHOD
Sixteen patients diagnosed with alpha-mannosidosis who presented to four pediatric metabolic units were included in the study. The patients' medical records were analyzed and data on demographics, clinical presentation and laboratory findings were recorded.
RESULTS
Of the 16 patients (6 females, 10 males) with alpha mannosidosis included in the study, the mean age at the time of diagnosis was 79.4 ± 56.1 (16-208) months, and the mean diagnosis delay time was 57.9 ± 51.9 (4-181) months. Hearing loss was the primary manifestation found in seven out of 16 patients (43.8%), followed by speech delay in 37.8%. On clinical follow-up, 87.5% of patients experienced recurrent infections, mainly in the upper respiratory tract, with 12 requiring the use of a hearing aid. Hepatomegaly was found in six out of 13 patients who received abdominal ultrasonography; two out of 12 patients who underwent echocardiography were found to have mitral valve prolapse (16.6%). Upon neurological evaluation, five patients displayed no neurological manifestation. Delayed language development was observed in nine (56.3%) patients, intellectual disability in eight (50%) patients, and hypertonicity was identified in one (6.3%) patient with the severe form of the disease. Homozygous c.2477C>A (p.Ser826Ter) and homozygous c.967G>A (p.Glu323Lys) novel variants were detected in four patients and one patient, respectively. The most common variant observed in the study was c.2477C>A (p.Ser826Ter).
CONCLUSION
The present study identified two novel MAN2B1 variants. An evaluation of the long-term outcome of alpha-mannosidosis, in which the early initiation of enzyme replacement therapy (ERT) may lead to a better clinical outcome, can permit a better analysis of the effect of ERT on the natural progression of the disease.
Topics: Child; Male; Female; Humans; alpha-Mannosidosis; Intellectual Disability; Hearing Loss; Deafness; Enzyme Replacement Therapy
PubMed: 38382588
DOI: 10.1016/j.ejmg.2024.104927 -
Frontiers in Genetics 2023Alpha-mannosidosis caused by mutations in the gene is a rare genetic disorder characterized by physical abnormalities and intellectual disabilities. The objective of...
Alpha-mannosidosis caused by mutations in the gene is a rare genetic disorder characterized by physical abnormalities and intellectual disabilities. The objective of this study was to analyze the carrier frequency and estimated incidence of alpha-mannosidosis in East Asian populations, as limited data exists on its incidence in this group. In this study, a total of 125,748 exomes from the gnomAD database was analyzed. Additionally, 5,305 data from the KOVA and 1,722 data from the KRGDB, both representing Korean populations, were included. The global carrier frequency of alpha-mannosidosis in gnomAD was 0.23%; the highest carrier frequency was observed in the Finnish at 0.49%, and East Asians had the second highest carrier frequency at 0.30%. Globally, the approximate incidence of alpha-mannosidosis was calculated at 1 in 784,535, l in 166,801 Europeans (Finnish), and l in 431,689 East Asians. By integrating the data from the 8,936 Koreans in gnomAD Korean, KOVA and KRGDB, the carrier frequency of alpha-mannosidosis in the Korean population was 0.04% and estimated incidence was 1 in 19,963,024. This study is the first to investigate the carrier frequencies of alpha-mannosidosis in East Asians and Koreans, including specific subpopulations, utilizing gnomAD and the Korean genomic database. The variant spectrum of genes in East Asians showed significant differences compared to other ethnic groups. Our data provide valuable reference information for future investigations into alpha-mannosidosis, aiding in understanding the genetic diversity and specific variants associated with the condition in East Asian populations.
PubMed: 38107468
DOI: 10.3389/fgene.2023.1297543 -
Gene Jan 2024A 6-month-old cat of unknown ancestry presented for a neurologic evaluation due to progressive motor impairment. Complete physical and neurologic examinations suggested...
A 6-month-old cat of unknown ancestry presented for a neurologic evaluation due to progressive motor impairment. Complete physical and neurologic examinations suggested the disorder was likely to be hereditary, although the signs were not consistent with any previously described inherited disorders in cats. Due to the progression of disease signs including severely impaired motor function and cognitive decline, the cat was euthanized at approximately 10.5 months of age. Whole genome sequence analysis identified a homozygous missense variant c.2506G > A in MANBA that predicts a p.Gly836Arg alteration in the encoded lysosomal enzyme β -mannosidase. This variant was not present in the whole genome or whole exome sequences of any of the 424 cats represented in the 99 Lives Cat Genome dataset. β -Mannosidase enzyme activity was undetectable in brain tissue homogenates from the affected cat, whereas α-mannosidase enzyme activities were elevated compared to an unaffected cat. Postmortem examination of brain and retinal tissues revealed massive accumulations of vacuolar inclusions in most cells, similar to those reported in animals of other species with hereditary β -mannosidosis. Based on these findings, the cat likely suffered from β -mannosidosis due to the abolition of β -mannosidase activity associated with the p.Gly836Arg amino acid substitution. p.Gly836 is located in the C-terminal region of the protein and was not previously known to be involved in modulating enzyme activity. In addition to the vacuolar inclusions, some cells in the brain of the affected cat contained inclusions that exhibited lipofuscin-like autofluorescence. Electron microscopic examinations suggested these inclusions formed via an autophagy-like process.
Topics: Cats; Animals; beta-Mannosidosis; beta-Mannosidase; Mutation, Missense
PubMed: 37913889
DOI: 10.1016/j.gene.2023.147941 -
Clinical Dysmorphology Jan 2024Alpha-mannosidosis (MIM #248500) is an ultra-rare autosomal recessive lysosomal storage disease with multi-system involvement and a wide phenotypic spectrum. Information...
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.
Topics: Male; Female; Humans; Infant, Newborn; Infant; Child, Preschool; Child; Adolescent; Young Adult; Adult; Middle Aged; Aged; Aged, 80 and over; alpha-Mannosidosis; Delayed Diagnosis; Mental Disorders; Inheritance Patterns; Italy
PubMed: 37791705
DOI: 10.1097/MCD.0000000000000474 -
Genes Aug 2023A 7-month-old Doberman Pinscher dog presented with progressive neurological signs and brain atrophy suggestive of a hereditary neurodegenerative disorder. The dog was...
A Homozygous Missense Mutation in a Doberman Pinscher Dog with Neurodegeneration, Cytoplasmic Vacuoles, Autofluorescent Storage Granules, and an α-Mannosidase Deficiency.
A 7-month-old Doberman Pinscher dog presented with progressive neurological signs and brain atrophy suggestive of a hereditary neurodegenerative disorder. The dog was euthanized due to the progression of disease signs. Microscopic examination of tissues collected at the time of euthanasia revealed massive accumulations of vacuolar inclusions in cells throughout the central nervous system, suggestive of a lysosomal storage disorder. A whole genome sequence generated with DNA from the affected dog contained a likely causal, homozygous missense variant in that predicted an Asp104Gly amino acid substitution that was unique among whole genome sequences from over 4000 dogs. A lack of detectable α-mannosidase enzyme activity confirmed a diagnosis of a-mannosidosis. In addition to the vacuolar inclusions characteristic of α-mannosidosis, the dog exhibited accumulations of autofluorescent intracellular inclusions in some of the same tissues. The autofluorescence was similar to that which occurs in a group of lysosomal storage disorders called neuronal ceroid lipofuscinoses (NCLs). As in many of the NCLs, some of the storage bodies immunostained strongly for mitochondrial ATP synthase subunit c protein. This protein is not a substrate for α-mannosidase, so its accumulation and the development of storage body autofluorescence were likely due to a generalized impairment of lysosomal function secondary to the accumulation of α-mannosidase substrates. Thus, it appears that storage body autofluorescence and subunit c accumulation are not unique to the NCLs. Consistent with generalized lysosomal impairment, the affected dog exhibited accumulations of intracellular inclusions with varied and complex ultrastructural features characteristic of autophagolysosomes. Impaired autophagic flux may be a general feature of this class of disorders that contributes to disease pathology and could be a target for therapeutic intervention. In addition to storage body accumulation, glial activation indicative of neuroinflammation was observed in the brain and spinal cord of the proband.
Topics: Animals; Dogs; alpha-Mannosidase; alpha-Mannosidosis; Lysosomal Storage Diseases; Lysosomes; Mutation, Missense; Vacuoles; Neurodegenerative Diseases
PubMed: 37761886
DOI: 10.3390/genes14091746 -
International Journal of Surgery... Sep 2023Alpha-mannosidosis (AM) is an autosomal recessive lysosomal storage disorder caused by reduced activity of the enzyme alpha-mannosidase. The disease is characterized by...
Alpha-mannosidosis (AM) is an autosomal recessive lysosomal storage disorder caused by reduced activity of the enzyme alpha-mannosidase. The disease is characterized by immunodeficiency, facial and skeletal abnormalities, impaired hearing, and intellectual disability. The clinical subtype of AM shows considerable variability in an individual, and at present, at least three clinical subtypes are suggested. Diagnosis is made by identification of deficiency of α-mannosidase activity in nucleated cells, like fibroblasts. The children are often born apparently normal as the disease is insidiously progressive, hence making early diagnosis essential. Along with supportive care, long-term therapeutic options include hematopoietic stem cell transplant, bone marrow transplantation, and enzyme replacement therapy. The possible benefits of these procedures must be weighed against the overall risk of procedure-related morbidity and mortality. Velmanase alfa is the first human recombinant form of alpha-mannosidase licensed and available for long-term enzyme replacement therapy. It is approved for treating non-neurologic manifestations of mild to moderate AM. The results obtained from different clinical trials provide evidence of the positive clinical effect of the recombinant enzyme on patients with AM. Different routes of diagnosis and unspecific initial symptoms of the disease lead to a delay in the initiation of treatment, resulting in accumulative morbidity. Thus, there is a dire necessity to create more awareness. Furthermore, additional multiple large-scale trials are needed to evaluate the long-term safety and efficacy of velmanase alfa.
Topics: Child; Humans; alpha-Mannosidosis; alpha-Mannosidase; Bone Marrow Transplantation; Cognition; Enzyme Replacement Therapy
PubMed: 37352513
DOI: 10.1097/JS9.0000000000000528 -
JIMD Reports Mar 2023Alpha-mannosidosis (AM), an autosomal recessive disorder caused by pathogenic biallelic variants in the gene, leads to lysosomal alpha-mannosidase deficiency and...
Relationship between genotype/subcellular localization subgroups, antidrug antibody detection, and long-term velmanase alfa treatment outcomes in patients with alpha-mannosidosis.
Alpha-mannosidosis (AM), an autosomal recessive disorder caused by pathogenic biallelic variants in the gene, leads to lysosomal alpha-mannosidase deficiency and accumulation of mannose-rich oligosaccharides. Velmanase alfa (VA), a recombinant human lysosomal alpha-mannosidase, is the first enzyme replacement therapy for non-neurological symptoms of AM. Previously, a potential relationship was identified between three genotype/subcellular localization subgroups (G1, G2, and G3) and AM disease severity. In VA-treated patients with AM, it is unknown if a relationship exists between genotype/subcellular localization subgroups, antidrug antibodies (ADAs), and infusion-related reactions (IRRs). This pooled analysis evaluated data from 33 VA-treated patients with AM to investigate this relationship. Overall, 10 patients were positive for ADAs, 4 of whom had treatment-emergent ADAs (G1: 3/7 [43%]; G2: 1/17 [6%]; G3: 0/9). Treatment-emergent ADA-positive patients with relatively high titers ( = 2; G1: 1012 U/ml and G2: 440 U/ml) experienced mild/moderate IRRs that were well-managed; patients with lower titers ( = 2) experienced no IRRs. Overall, changes from baseline in serum oligosaccharides and immunoglobulin G levels did not vary between ADA-positive and ADA-negative patients, suggesting a similar effect of VA treatment regardless of ADA status in most patients. Clinical outcomes (3MSCT and 6MWT) were also similar in most patients regardless of ADA status. While further studies are needed, these data suggest a relationship between genotype/subcellular localization subgroups and ADA development, with G1 and G2 subgroups more likely to develop ADAs and IRRs. Regardless, this study suggests that ADAs have limited effect on the clinical impact of VA in most patients with AM.
PubMed: 36873087
DOI: 10.1002/jmd2.12349