Dataset Information

GPI-anchor and GPI-anchored protein expression in PMM2-CDG patients.

ABSTRACT:

Background

Mutations in PMM2 impair phosphomannomutase-2 activity and cause the most frequent congenital disorder of glycosylation, PMM2-CDG. Mannose-1-phosphate, that is deficient in this disorder, is also implicated in the biosynthesis of glycosylphosphatidyl inositol (GPI) anchors.

Objective

To evaluate whether GPI-anchor and GPI-anchored proteins are defective in PMM2-CDG patients.

Methods

The expression of GPI-anchor and seven GPI-anchored proteins was evaluated by flow cytometry in different cell types from twelve PMM2-CDG patients. Additionally, neutrophil CD16 and plasma hepatic proteins were studied by Western blot. Transferrin glycoforms were evaluated by HPLC.

Results

Patients and controls had similar surface expression of GPI-anchor and most GPI-anchored proteins. Nevertheless, patients displayed a significantly diminished binding of two anti-CD16 antibodies (3G8 and KD1) to neutrophils and also of anti-CD14 (61D3) to monocytes. Interestingly, CD16 immunostaining and asialotransferrin levels significantly correlated with patients' age. Analysis by flow cytometry of CD14 with M?P9, and CD16 expression in neutrophils by Western blot using H-80 ruled out deficiencies of these antigens.

Conclusions

PMM2 mutations do not impair GPI-anchor or GPI-anchored protein expression. However, the glycosylation anomalies caused by PMM2 mutations might affect the immunoreactivity of monoclonal antibodies and lead to incorrect conclusions about the expression of different proteins, including GPI-anchored proteins. Neutrophils and monocytes are sensitive to PMM2 mutations, leading to abnormal glycosylation in immune receptors, which might potentially affect their affinity to their ligands, and contribute to infection. This study also confirms less severe hypoglycosylation defects in older PMM2-CDG patients.

SUBMITTER: de la Morena-Barrio ME

PROVIDER: S-EPMC4016514 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Publications

GPI-anchor and GPI-anchored protein expression in PMM2-CDG patients.

de la Morena-Barrio Maria E ME Hernández-Caselles Trinidad T Corral Javier J García-López Roberto R Martínez-Martínez Irene I Pérez-Dueñas Belen B Altisent Carmen C Sevivas Teresa T Kristensen Soren R SR Guillén-Navarro Encarna E Miñano Antonia A Vicente Vicente V Jaeken Jaak J Lozano Maria L ML

Orphanet journal of rare diseases 20131020

<h4>Background</h4>Mutations in PMM2 impair phosphomannomutase-2 activity and cause the most frequent congenital disorder of glycosylation, PMM2-CDG. Mannose-1-phosphate, that is deficient in this disorder, is also implicated in the biosynthesis of glycosylphosphatidyl inositol (GPI) anchors.<h4>Objective</h4>To evaluate whether GPI-anchor and GPI-anchored proteins are defective in PMM2-CDG patients.<h4>Methods</h4>The expression of GPI-anchor and seven GPI-anchored proteins was evaluated by flo ...[more]

PMID: 24139637

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Project description:Phosphomannomutase 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.Our 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.ICARS 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.ICARS 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

GPI-anchor and GPI-anchored protein expression in PMM2-CDG patients.

Background

Objective

Methods

Results

Conclusions

Publications

GPI-anchor and GPI-anchored protein expression in PMM2-CDG patients.

Similar Datasets

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