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Spontaneous improvement of carbohydrate-deficient transferrin in PMM2-CDG without mannose observed in CDG natural history study.

ABSTRACT: A recent report on long-term dietary mannose supplementation in phosphomannomutase 2 deficiency (PMM2-CDG) claimed improved glycosylation and called for double-blind randomized study of the dietary supplement in PMM2-CDG patients. A lack of efficacy of short-term mannose supplementation in multiple prior reports challenge this study's conclusions. Additionally, some CDG types have previously been reported to demonstrate spontaneous improvement in glycosylated biomarkers, including transferrin. We have likewise observed improvements in transferrin glycosylation without mannose supplementation. This observation questions the reliability of transferrin as a therapeutic outcome measure in clinical trials for PMM2-CDG. We are concerned that renewed focus on mannose therapy in PMM2-CDG will detract from clinical trials of more promising therapies. Approaches to increase efficiency of clinical trials and ultimately improve patients' lives requires prospective natural history studies and identification of reliable biomarkers linked to clinical outcomes in CDG. Collaborations with patients and families are essential to identifying meaningful study outcomes.

SUBMITTER: Witters P

PROVIDER: S-EPMC7908710 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Spontaneous improvement of carbohydrate-deficient transferrin in PMM2-CDG without mannose observed in CDG natural history study.

Witters Peter P Edmondson Andrew C AC Lam Christina C Johnsen Christin C Patterson Marc C MC Raymond Kimiyo M KM He Miao M Freeze Hudson H HH Morava Eva E

Orphanet journal of rare diseases 20210225 1

A recent report on long-term dietary mannose supplementation in phosphomannomutase 2 deficiency (PMM2-CDG) claimed improved glycosylation and called for double-blind randomized study of the dietary supplement in PMM2-CDG patients. A lack of efficacy of short-term mannose supplementation in multiple prior reports challenge this study's conclusions. Additionally, some CDG types have previously been reported to demonstrate spontaneous improvement in glycosylated biomarkers, including transferrin. W ...[more]

PMID: 33632285

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Project description:BackgroundPhosphomannomutase deficiency (PMM2-CDG) is the most frequent congenital disorder of glycosylation. The cerebellum is nearly always affected in PMM2-CDG patients, a cerebellar atrophy progression is observed, and cerebellar dysfunction is their main daily functional limitation. Different therapeutic agents are under development, and clinical evaluation of drug candidates will require a standardized score of cerebellar dysfunction. We aim to assess the validity of the International Cooperative Ataxia Rating Scale (ICARS) in children and adolescents with genetically confirmed PMM2-CDG deficiency. We compare ICARS results with the Nijmegen Pediatric CDG Rating Scale (NPCRS), neuroimaging, intelligence quotient (IQ) and molecular data.MethodsOur observational study included 13 PMM2-CDG patients and 21 control subjects. Ethical permissions and informed consents were obtained. Three independent child neurologists rated PMM2-CDG patients and control subjects using the ICARS. A single clinician administered the NPCRS. All patients underwent brain MRI, and the relative diameter of the midsagittal vermis was measured. Psychometric evaluations were available in six patients. The Mann-Whitney U test was used to compare ICARS between patients and controls. To evaluate inter-observer agreement in patients' ICARS ratings, intraclass correlation coefficients (ICC) were calculated. ICARS internal consistency was evaluated using Cronbach's alpha. Spearman's rank correlation coefficient test was used to correlate ICARS with NPCRS, midsagittal vermis relative diameter and IQ.ResultsICARS and ICARS subscores differed between patients and controls (p < 0.001). Interobserver agreement of ICARS was "almost perfect" (ICC = 0.99), with a "good" internal reliability (Cronbach's alpha = 0.72). ICARS was significantly correlated with the total NPCRS score (rs 0.90, p < 0.001). However, there was no agreement regarding categories of severity. Regarding neuroimaging, inverse correlations between ICARS and midsagittal vermis relative diameter (rs -0.85, p = 0.003) and IQ (rs -0.94, p = 0.005) were found. Patients bearing p.E93A, p.C241S or p.R162W mutations presented a milder phenotype.ConclusionsICARS is a reliable instrument for assessment of PMM2-CDG patients, without significant inter-rater variability. Despite our limited sample size, the results show a good correlation between functional cerebellar assessment, IQ and neuroimaging. For the first a correlation between ICARS, neuroimaging and IQ in PMM2-CDG patients has been demonstrated.

Dataset Information

Spontaneous improvement of carbohydrate-deficient transferrin in PMM2-CDG without mannose observed in CDG natural history study.

Publications

Spontaneous improvement of carbohydrate-deficient transferrin in PMM2-CDG without mannose observed in CDG natural history study.

Similar Datasets

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