Mucolipidosis Type II (MLII; I‑cell disease) — Disease Characteristics Research Report

Executive summary (current understanding)

Mucolipidosis type II (MLII) is an ultra-rare, severe, autosomal recessive lysosomal storage disorder (LSD) caused by biallelic pathogenic variants in GNPTAB, resulting in deficiency of N‑acetylglucosamine‑1‑phosphotransferase (GlcNAc‑1‑phosphotransferase) and failure to generate mannose‑6‑phosphate (M6P) targeting signals on many lysosomal hydrolases. Consequently, lysosomal enzymes are missorted and hypersecreted, leading to multisystem storage pathology with prenatal/neonatal onset, progressive skeletal disease (dysostosis multiplex), growth failure, cardiorespiratory complications, and profound developmental impairment; survival is typically limited to childhood in classic MLII (dogterom2021mucolipidosistypeii pages 1-2, he2023outcomesafterhsct pages 1-2).

Recent 2023–2024 literature emphasizes (i) improved quantitative longitudinal neurodevelopmental characterization (suggesting sustained but very slow skill gain rather than clear progressive neurodegeneration in one cohort) and (ii) advances in biochemical screening/diagnosis using multiplex MS/MS enzyme activity patterns in dried blood spots (DBS) as a route to earlier detection (ammer2023cnsmanifestationsin pages 1-2, hong2023multiplextandemmass pages 1-2).

1. Disease information

1.1 Definition and overview

MLII (I‑cell disease) is a GNPTAB-related mucolipidosis in which loss of GlcNAc‑1‑phosphotransferase activity prevents M6P tagging of lysosomal enzymes in the Golgi, causing their secretion rather than lysosomal delivery, with secondary intracellular accumulation of undegraded macromolecules (he2023outcomesafterhsct pages 1-2, dogterom2021mucolipidosistypeii pages 1-2).

1.2 Key identifiers and synonyms

A normalization table for identifiers captured in the retrieved evidence is provided below.

Table: This table summarizes the core disease nomenclature and identifiers for mucolipidosis type II (I-cell disease), including related OMIM entries and causal genes. It is useful as a normalization reference for a disease knowledge base when some ontology identifiers were not available in the retrieved evidence.

Note on missing ontology IDs: In this tool run, MONDO, Orphanet, ICD‑10/ICD‑11, and MeSH identifiers were not present in the retrieved full texts and therefore cannot be asserted with citation-compliant evidence here (artifact-00).

1.3 Evidence source type

The evidence base here includes aggregated, disease-level systematic review data (historic literature through Aug 2019), recent retrospective and cohort studies, single-patient clinical reports, and observational clinicaltrials.gov protocols (dogterom2021mucolipidosistypeii pages 3-4, ammer2023cnsmanifestationsin pages 1-2, NCT01891422 chunk 1).

2. Etiology

2.1 Disease causal factors

• Primary cause (genetic): Biallelic pathogenic variants in GNPTAB (autosomal recessive) causing deficiency/absence of GlcNAc‑1‑phosphotransferase and failure of M6P-dependent lysosomal enzyme trafficking (dogterom2021mucolipidosistypeii pages 1-2, he2023outcomesafterhsct pages 1-2).
• Related allelic disorders: Reduced residual GlcNAc‑1‑phosphotransferase activity yields attenuated phenotypes classified as mucolipidosis type III α/β; GNPTG variants primarily cause MLIII γ (dogterom2021mucolipidosistypeii pages 1-2, feng2024clinicalandmolecular pages 1-2).

2.2 Risk factors / protective factors / GxE

For a Mendelian disease with early onset, non-genetic risk factors and protective factors are not well established in the retrieved evidence. Disease risk is driven by inheritance of pathogenic GNPTAB alleles (dogterom2021mucolipidosistypeii pages 1-2). Gene–environment interactions were not identified in the retrieved MLII-specific sources.

3. Phenotypes (clinical features; HPO suggestions)

A phenotype-to-HPO mapping table with frequencies (when available) is provided below.

Table: This table summarizes the major clinical and imaging phenotypes reported for mucolipidosis type II, including onset, progression, and approximate frequencies where available. It is useful for populating phenotype fields in a disease knowledge base and mapping features to HPO terms.

3.1 Recent quantitative CNS phenotype characterization (2023)

A 2023 retrospective longitudinal analysis of 11 MLII patients reported profound impairment but continued developmental gains: mean developmental quotient (DQ) at last assessment 36.7% (SD 20.4) and an average gain of 0.28 age-equivalent score points/month (95% CI 0.17–0.38) (ammer2023cnsmanifestationsin pages 1-2). The abstract concludes: “MLII is associated with profound developmental impairment, but not with neurodegeneration and neurocognitive decline.” (Journal of Clinical Medicine; published June 2023; URL in citation metadata) (ammer2023cnsmanifestationsin pages 1-2).

3.2 Visual evidence (neurodevelopment and MRI frequencies)

Figure/table crops from the 2023 CNS cohort summarize longitudinal neurocognitive trajectories and the frequencies of MRI abnormalities (including cervical spinal stenosis and mild brain atrophy) (ammer2023cnsmanifestationsin media 4b113608, ammer2023cnsmanifestationsin media 18508077).

4. Genetic / molecular information

4.1 Causal genes

• GNPTAB (major causal gene for MLII; encodes α/β subunits of GlcNAc‑1‑phosphotransferase) (he2023outcomesafterhsct pages 1-2, dogterom2021mucolipidosistypeii pages 1-2).
• GNPTG is relevant primarily to MLIII γ and for differential diagnosis within mucolipidosis subtypes (dogterom2021mucolipidosistypeii pages 1-2).

4.2 Variant classes and genotype–phenotype

Severe GNPTAB loss-of-function (e.g., frameshift/nonsense) correlates with MLII, while partial activity is associated with MLIII α/β (dogterom2021mucolipidosistypeii pages 1-2). Recent cohort work continues expanding variant spectra: a 2024 Chinese series reported detection of GNPTAB mutations in 87.5% of alleles and identified several novel variants, noting plasma arylsulfatase A and hexosaminidase A were significantly elevated with normal urinary GAGs (BMC Pediatrics; 2024; https://doi.org/10.1186/s12887-024-05223-x) (feng2024clinicalandmolecular pages 1-2).

A 2023 HSCT case report described novel compound heterozygous GNPTAB variants (c.673C>T; c.1090C>T) in China (Frontiers in Pediatrics; July 2023; https://doi.org/10.3389/fped.2023.1199489) (he2023outcomesafterhsct pages 1-2).

4.3 Functional consequence

Loss of M6P tagging leads to hypersecretion of lysosomal hydrolases and multi-substrate lysosomal accumulation (e.g., GAGs and lipids), a hallmark reflected clinically by elevated circulating lysosomal enzyme activities (he2023outcomesafterhsct pages 1-2, feng2024clinicalandmolecular pages 1-2).

5. Environmental information

No MLII-specific environmental, lifestyle, or infectious causal factors were identified in the retrieved evidence; MLII is primarily explained by GNPTAB-mediated enzyme trafficking failure (dogterom2021mucolipidosistypeii pages 1-2).

6. Mechanism / pathophysiology

6.1 Core pathway (M6P-dependent lysosomal enzyme trafficking)

GlcNAc‑1‑phosphotransferase is required for the first step in M6P tagging of lysosomal enzymes; failure of this step leads to impaired lysosomal targeting and extracellular hypersecretion of hydrolases, with intracellular deficiency of many lysosomal enzymes (khan2020mucolipidosesoverviewpast pages 1-3, he2023outcomesafterhsct pages 1-2).

Suggested pathways/ontologies: - GO Biological Process (suggested): lysosomal enzyme targeting; protein glycosylation; Golgi vesicle transport; lysosomal organization. - GO Cellular Component (suggested): Golgi apparatus; lysosome.

6.2 Downstream cellular consequences (recent mechanistic synthesis; 2024)

Recent mechanistic synthesis in Gnptab-deficient models links defective M6P sorting to: - NPC2 missorting and reduced lysosomal NPC2, contributing to cholesterol trafficking defects and cholesterol accumulation (badenetti2024investigatingneuronalpathogenesisa pages 24-28). - Autophagy impairment with accumulation of p62 and LC3-II, increased lysosome number (LAMP1/2 elevation), and defective autolysosomes; mitochondrial dysfunction in MLII fibroblasts could be rescued by inhibiting autophagosome generation, implicating impaired autophagic flux in pathogenesis (badenetti2024investigatingneuronalpathogenesisa pages 24-28).

Suggested GO terms (process): autophagy; cholesterol transport; lysosome organization.

Suggested CL terms (cell types): fibroblast; cardiomyocyte; neuron (based on cited model systems) (badenetti2024investigatingneuronalpathogenesisa pages 24-28).

7. Anatomical structures affected

MLII is multisystemic; heavily affected systems include: - Skeletal system (dysostosis multiplex, joint restriction, hip dysplasia) (ammer2023cnsmanifestationsin pages 4-6, dogterom2021mucolipidosistypeii pages 3-4). - Respiratory system (recurrent infections/respiratory failure; major cause of death) (dogterom2021mucolipidosistypeii pages 3-4). - Cardiovascular system (cardiac failure and combined cardiopulmonary causes of death) (dogterom2021mucolipidosistypeii pages 3-4). - Central nervous system (severe developmental impairment; cervical spinal stenosis frequent on imaging) (ammer2023cnsmanifestationsin pages 1-2, ammer2023cnsmanifestationsin media 4b113608).

UBERON suggestions (term names): bone; cartilage; heart; lung; brain; cervical spinal cord.

8. Temporal development (onset and progression)

• Onset: Typically prenatal/neonatal/early infancy. Systematic review data reported median age at first symptoms 0.0 years (IQR 0.0–0.3) for MLII (dogterom2021mucolipidosistypeii pages 3-4).
• Diagnosis: Median age at diagnosis 0.7 years (IQR 0.2–1.4) in pooled literature (dogterom2021mucolipidosistypeii pages 3-4).
• Progression/course: Progressive multisystem disease; leading fatal complications are pulmonary and cardiac (dogterom2021mucolipidosistypeii pages 3-4).

9. Inheritance and population

9.1 Inheritance

Autosomal recessive inheritance is consistently reported for MLII (dogterom2021mucolipidosistypeii pages 1-2).

9.2 Epidemiology and survival statistics

A systematic review of 843 published MLII/MLIII cases provides the most consolidated quantitative evidence in the retrieved corpus: - Median survival (Kaplan–Meier) for MLII: 5.0 years (95% CI 3.8–6.2) (dogterom2021mucolipidosistypeii pages 3-4). - Median age of death: 1.8 years (IQR 0.2–4.1) (dogterom2021mucolipidosistypeii pages 3-4). - Reported causes of death among MLII cases included pneumonia (32/93), respiratory failure (24/93), and cardiac failure (15/93), consistent with cardiopulmonary dominance (dogterom2021mucolipidosistypeii pages 3-4).

The same review reported estimated combined incidence of mucolipidosis (MLII/III overall) of 0.22–2.70 per 100,000 live births (dogterom2021mucolipidosistypeii pages 1-2).

10. Diagnostics

A structured diagnostic workflow summary is provided below.

Table: This table summarizes the main diagnostic modalities used for mucolipidosis type II, from plasma enzyme testing and DBS MS/MS screening to GNPTAB confirmation and imaging. It is useful as a concise, evidence-linked workflow for populating diagnostic fields in a disease knowledge base.

10.1 Key diagnostic concepts and definitions

• “Hypersecretion” signature: In MLII, lysosomal enzyme activities in plasma can be markedly increased due to missorting; one recent cohort used 10–20× above normal as a supportive diagnostic criterion, while urinary GAGs may remain normal (feng2024clinicalandmolecular pages 1-2).

10.2 Recent development: multiplex MS/MS enzyme activity assay (2023)

Hong et al. (Molecular Genetics and Metabolism Reports; June 2023; https://doi.org/10.1016/j.ymgmr.2023.100978) reported a multiplex tandem MS DBS assay measuring activities of 12 lysosomal enzymes and found acid sphingomyelinase (ASM), iduronate-2-sulfatase (IDS), and alpha-N-acetylglucosaminidase (NAGLU) were significantly elevated in MLII/III compared with newborn DBS (hong2023multiplextandemmass pages 1-2, hong2023multiplextandemmass pages 4-5). They suggest incorporating an elevated-activity cutoff could permit MLII/III detection as a secondary newborn-screening finding (hong2023multiplextandemmass pages 4-5).

10.3 Emerging biomarker research programs (real-world implementation)

• NCT01891422 (Completed; Greenwood Genetic Center; 2009 entry): Longitudinal observational study including MLII, designed to define natural history, document supportive therapies, and collect biospecimens (blood, urine, fibroblasts) alongside neuropsychological and skeletal imaging endpoints (NCT01891422 chunk 1).
• NCT02298673 (Withdrawn; CENTOGENE; 2018 entry): Proposed development/validation of an MS-based plasma biomarker for ML I–IV, including MLII, with robustness/specificity/stability testing up to 24 months (NCT02298673 chunk 2).

11. Outcome / prognosis

MLII carries a poor prognosis with early childhood mortality in classic disease; systematic review-derived median survival is 5.0 years and cardiopulmonary complications dominate reported causes of death (dogterom2021mucolipidosistypeii pages 3-4, dogterom2021mucolipidosistypeii pages 1-2).

A 2023 longitudinal CNS cohort adds nuance: profound developmental impairment is typical, but the cohort-level pattern did not support progressive neurocognitive decline over the observed period, with non-progressive/nonspecific MRI findings except frequent cervical spinal stenosis (ammer2023cnsmanifestationsin pages 1-2, ammer2023cnsmanifestationsin media 4b113608).

12. Treatment

A structured treatment/management summary (including MAXO term suggestions) is provided below.

Table: This table summarizes current real-world management of mucolipidosis type II, emphasizing supportive multidisciplinary care, the limited but important HSCT experience, and active translational research directions such as biomarker development and preclinical gene therapy.

12.1 Current standard of care and real-world management

There is no established curative or clearly disease-modifying therapy; management is largely supportive and multidisciplinary. In the systematic review, multiple “potential life-extending procedures” were reported in MLII, including HSCT/BMT/cord blood transplant, tracheostomy, gastrostomy, craniosynostosis surgery, cervical spine surgery, and cardiac interventions (dogterom2021mucolipidosistypeii pages 4-5).

12.2 HSCT (limited human evidence)

A 2023 case report explicitly states: “No cure for MLII exists.” and summarizes typical severity and outcomes; it reports an HSCT performed at 12 months with early engraftment and short-term motor improvements (Frontiers in Pediatrics; July 2023; https://doi.org/10.3389/fped.2023.1199489) (he2023outcomesafterhsct pages 1-2). The authors conclude: “Our data show that HSCT is a potential way to prolong the life of patients and improve their quality of life… the exact benefit remains unclear in MLII patients.” (he2023outcomesafterhsct pages 1-2).

12.3 Experimental / translational directions

No MLII-specific clinical gene therapy or ERT trials were identified in the retrieved evidence set; however, systematic review authors highlight gene therapy as a likely future direction for ML (dogterom2021mucolipidosistypeii pages 1-2). Translational efforts currently visible in retrieved sources include (i) biomarker discovery protocols and (ii) multiplex MS/MS approaches that could enable earlier detection and better endpoint definition (NCT02298673 chunk 2, hong2023multiplextandemmass pages 4-5).

13. Prevention

As a Mendelian disorder, primary prevention is primarily genetic: - Genetic counseling for autosomal recessive inheritance and family planning (suggested MAXO: genetic counseling). - Prenatal diagnosis / carrier testing are implied in the genetic-testing framework but not detailed in retrieved sources.

Newborn screening is not standard for MLII in the retrieved sources, but the DBS multiplex enzymology work provides a plausible route for secondary detection in LSD screening programs (hong2023multiplextandemmass pages 4-5).

14. Other species / natural disease

A naturally occurring MLII-like disease has been described in domestic cats with a GNPTAB nonsense variant and clinical/biochemical similarities to human MLII, positioning feline MLII as a large-animal model for pathophysiology and therapeutic exploration (BMC Veterinary Research; Dec 2018; https://doi.org/10.1186/s12917-018-1728-1) (wang2018agnptabnonsense pages 8-8).

15. Model organisms

Multiple model systems are used to study GNPTAB deficiency: - Mouse models: gene-trap and knock-in Gnptab models recapitulating key aspects of MLII, including elevated circulating lysosomal enzymes, skeletal pathology, and neurodegeneration in severe models (khan2020mucolipidosesoverviewpast pages 7-9). - Zebrafish: subunit-deficient zebrafish models are cited as informative for enzyme-specific mannose phosphorylation differences (wang2018agnptabnonsense pages 8-8). - Human cellular models: patient-derived fibroblasts (and other cell types) show characteristic storage and trafficking defects and are widely used to study downstream consequences such as cholesterol accumulation and impaired autophagy (badenetti2024investigatingneuronalpathogenesisa pages 24-28).

Key evidence statistics (quick reference)

• Median age at diagnosis: 0.7 years (dogterom2021mucolipidosistypeii pages 3-4).
• Median survival: 5.0 years (95% CI 3.8–6.2) (dogterom2021mucolipidosistypeii pages 3-4).
• Causes of death (examples): pneumonia 32/93, respiratory failure 24/93, cardiac failure 15/93 (dogterom2021mucolipidosistypeii pages 3-4).
• Developmental quotient (DQ) in one longitudinal cohort: mean 36.7% (SD 20.4) (ammer2023cnsmanifestationsin pages 1-2).
• Cervical spinal stenosis on MRI in one cohort: 63% (ammer2023cnsmanifestationsin pages 1-2, ammer2023cnsmanifestationsin media 4b113608).

Evidence gaps and constraints (for knowledge base curation)

1. Ontology identifiers (MONDO/Orphanet/ICD/MeSH) were not present in retrieved full texts during this run; they should be added from dedicated ontology resources (artifact-00).
2. Validated longitudinal biomarkers for treatment monitoring remain limited; clinicaltrials.gov shows biomarker discovery intent but one biomarker study was withdrawn (NCT02298673 chunk 2).
3. Clinical gene therapy/ERT trials for MLII were not identified in the retrieved evidence set; statements here are limited to prospects and platform-level developments rather than MLII-specific trial outcomes (dogterom2021mucolipidosistypeii pages 1-2).

References

1. (dogterom2021mucolipidosistypeii pages 1-2): Emma J. Dogterom, Margreet A.E.M. Wagenmakers, Martina Wilke, Serwet Demirdas, Nicole M. Muschol, Sandra Pohl, Jan C. van der Meijden, Dimitris Rizopoulos, Ans T. van der Ploeg, and Esmée Oussoren. Mucolipidosis type ii and type iii: a systematic review of 843 published cases. Genetics in Medicine, 23:2047-2056, Nov 2021. URL: https://doi.org/10.1038/s41436-021-01244-4, doi:10.1038/s41436-021-01244-4. This article has 44 citations and is from a highest quality peer-reviewed journal.

2. (he2023outcomesafterhsct pages 1-2): Si-jia He, Dong-jun Li, Wen-qiong Lv, Wen-hao Tang, Shu-wen Sun, Yi-ping Zhu, Ying Liu, Jin Wu, and Xiao-xi Lu. Outcomes after hsct for mucolipidosis ii (i-cell disease) caused by novel compound heterozygous gnptab mutations. Frontiers in Pediatrics, Jul 2023. URL: https://doi.org/10.3389/fped.2023.1199489, doi:10.3389/fped.2023.1199489. This article has 4 citations.

3. (ammer2023cnsmanifestationsin pages 1-2): Luise Sophie Ammer, Karolin Täuber, Anna Perez, Thorsten Dohrmann, Jonas Denecke, René Santer, Ulrike Blümlein, Ann-Kathrin Ozga, Sandra Pohl, and Nicole Maria Muschol. Cns manifestations in mucolipidosis type ii—a retrospective analysis of longitudinal data on neurocognitive development and neuroimaging in eleven patients. Journal of Clinical Medicine, 12:4114, Jun 2023. URL: https://doi.org/10.3390/jcm12124114, doi:10.3390/jcm12124114. This article has 8 citations.

4. (hong2023multiplextandemmass pages 1-2): Xinying Hong, Laura Pollard, Miao He, Michael H. Gelb, and Timothy C. Wood. Multiplex tandem mass spectrometry enzymatic activity assay for the screening and diagnosis of mucolipidosis type ii and iii. Jun 2023. URL: https://doi.org/10.1016/j.ymgmr.2023.100978, doi:10.1016/j.ymgmr.2023.100978. This article has 6 citations.

5. (badenetti2024investigatingneuronalpathogenesisa pages 24-28): L Badenetti. Investigating neuronal pathogenesis in mucopolysaccharidosis type ii and mucolipidosis type ii disease models. Unknown journal, 2024.

6. (khan2020mucolipidosesoverviewpast pages 1-3): Shaukat A. Khan and Saori C. Tomatsu. Mucolipidoses overview: past, present, and future. International Journal of Molecular Sciences, 21:6812, Sep 2020. URL: https://doi.org/10.3390/ijms21186812, doi:10.3390/ijms21186812. This article has 78 citations.

7. (feng2024clinicalandmolecular pages 1-2): Yuyu Feng, Yonglan Huang, Xiaoyuan Zhao, Huiying Sheng, Xueying Su, Xi Yin, Liu Li, and Wen Zhang. Clinical and molecular characteristics of 20 chinese probands with mucolipidosis type ii and iii alpha/beta. BMC Pediatrics, Dec 2024. URL: https://doi.org/10.1186/s12887-024-05223-x, doi:10.1186/s12887-024-05223-x. This article has 2 citations and is from a peer-reviewed journal.

8. (dogterom2021mucolipidosistypeii pages 3-4): Emma J. Dogterom, Margreet A.E.M. Wagenmakers, Martina Wilke, Serwet Demirdas, Nicole M. Muschol, Sandra Pohl, Jan C. van der Meijden, Dimitris Rizopoulos, Ans T. van der Ploeg, and Esmée Oussoren. Mucolipidosis type ii and type iii: a systematic review of 843 published cases. Genetics in Medicine, 23:2047-2056, Nov 2021. URL: https://doi.org/10.1038/s41436-021-01244-4, doi:10.1038/s41436-021-01244-4. This article has 44 citations and is from a highest quality peer-reviewed journal.

9. (NCT01891422 chunk 1): Longitudinal Studies of the Glycoproteinoses. Greenwood Genetic Center. 2009. ClinicalTrials.gov Identifier: NCT01891422

10. (ammer2023cnsmanifestationsin pages 4-6): Luise Sophie Ammer, Karolin Täuber, Anna Perez, Thorsten Dohrmann, Jonas Denecke, René Santer, Ulrike Blümlein, Ann-Kathrin Ozga, Sandra Pohl, and Nicole Maria Muschol. Cns manifestations in mucolipidosis type ii—a retrospective analysis of longitudinal data on neurocognitive development and neuroimaging in eleven patients. Journal of Clinical Medicine, 12:4114, Jun 2023. URL: https://doi.org/10.3390/jcm12124114, doi:10.3390/jcm12124114. This article has 8 citations.

11. (ammer2023cnsmanifestationsin media 4b113608): Luise Sophie Ammer, Karolin Täuber, Anna Perez, Thorsten Dohrmann, Jonas Denecke, René Santer, Ulrike Blümlein, Ann-Kathrin Ozga, Sandra Pohl, and Nicole Maria Muschol. Cns manifestations in mucolipidosis type ii—a retrospective analysis of longitudinal data on neurocognitive development and neuroimaging in eleven patients. Journal of Clinical Medicine, 12:4114, Jun 2023. URL: https://doi.org/10.3390/jcm12124114, doi:10.3390/jcm12124114. This article has 8 citations.

12. (ammer2021ishematopoieticstem pages 1-2): Luise Sophie Ammer, Sandra Pohl, Sandra Rafaela Breyer, Charlotte Aries, Jonas Denecke, Anna Perez, Martin Petzoldt, Johanna Schrum, Ingo Müller, and Nicole Maria Muschol. Is hematopoietic stem cell transplantation a therapeutic option for mucolipidosis type ii? Mar 2021. URL: https://doi.org/10.1016/j.ymgmr.2020.100704, doi:10.1016/j.ymgmr.2020.100704. This article has 9 citations.

13. (ammer2023cnsmanifestationsin media 18508077): Luise Sophie Ammer, Karolin Täuber, Anna Perez, Thorsten Dohrmann, Jonas Denecke, René Santer, Ulrike Blümlein, Ann-Kathrin Ozga, Sandra Pohl, and Nicole Maria Muschol. Cns manifestations in mucolipidosis type ii—a retrospective analysis of longitudinal data on neurocognitive development and neuroimaging in eleven patients. Journal of Clinical Medicine, 12:4114, Jun 2023. URL: https://doi.org/10.3390/jcm12124114, doi:10.3390/jcm12124114. This article has 8 citations.

14. (hong2023multiplextandemmass pages 4-5): Xinying Hong, Laura Pollard, Miao He, Michael H. Gelb, and Timothy C. Wood. Multiplex tandem mass spectrometry enzymatic activity assay for the screening and diagnosis of mucolipidosis type ii and iii. Jun 2023. URL: https://doi.org/10.1016/j.ymgmr.2023.100978, doi:10.1016/j.ymgmr.2023.100978. This article has 6 citations.

15. (NCT02298673 chunk 1): Biomarker for Mucolipidosis Disorder Type I, II, III, IV (BioML). CENTOGENE GmbH Rostock. 2018. ClinicalTrials.gov Identifier: NCT02298673

16. (NCT02298673 chunk 2): Biomarker for Mucolipidosis Disorder Type I, II, III, IV (BioML). CENTOGENE GmbH Rostock. 2018. ClinicalTrials.gov Identifier: NCT02298673

17. (dogterom2021mucolipidosistypeii pages 4-5): Emma J. Dogterom, Margreet A.E.M. Wagenmakers, Martina Wilke, Serwet Demirdas, Nicole M. Muschol, Sandra Pohl, Jan C. van der Meijden, Dimitris Rizopoulos, Ans T. van der Ploeg, and Esmée Oussoren. Mucolipidosis type ii and type iii: a systematic review of 843 published cases. Genetics in Medicine, 23:2047-2056, Nov 2021. URL: https://doi.org/10.1038/s41436-021-01244-4, doi:10.1038/s41436-021-01244-4. This article has 44 citations and is from a highest quality peer-reviewed journal.

18. (khan2020mucolipidosesoverviewpast pages 18-20): Shaukat A. Khan and Saori C. Tomatsu. Mucolipidoses overview: past, present, and future. International Journal of Molecular Sciences, 21:6812, Sep 2020. URL: https://doi.org/10.3390/ijms21186812, doi:10.3390/ijms21186812. This article has 78 citations.

19. (wang2018agnptabnonsense pages 8-8): Ping Wang, Hamutal Mazrier, Jessica Caverly Rae, Karthik Raj, and Urs Giger. A gnptab nonsense variant is associated with feline mucolipidosis ii (i-cell disease). BMC Veterinary Research, Dec 2018. URL: https://doi.org/10.1186/s12917-018-1728-1, doi:10.1186/s12917-018-1728-1. This article has 10 citations and is from a peer-reviewed journal.

20. (khan2020mucolipidosesoverviewpast pages 7-9): Shaukat A. Khan and Saori C. Tomatsu. Mucolipidoses overview: past, present, and future. International Journal of Molecular Sciences, 21:6812, Sep 2020. URL: https://doi.org/10.3390/ijms21186812, doi:10.3390/ijms21186812. This article has 78 citations.

Artifacts

• Edison artifact artifact-00
• Edison artifact artifact-01
• Edison artifact artifact-02
• Edison artifact artifact-03