PMM2-CDG is the most common congenital disorder of glycosylation (CDG) accounting for almost 65% of known CDG cases affecting N-glycosylation. Abnormalities in N-glycosylation could have a negative impact on many endocrine axes. There is very little known on the effect of impaired N-glycosylation on the hypothalamic-pituitary-adrenal axis function and whether CDG patients are at risk of secondary adrenal insufficiency and decreased adrenal cortisol production. Cortisol and ACTH concentrations were simultaneously measured between 7:44 am to 1 pm in forty-three subjects (20 female, median age 12.8 years, range 0.1 to 48.6 years) participating in an ongoing international, multi-center Natural History study for PMM2-CDG (ClinicalTrials.gov Identifier: NCT03173300). Of the 43 subjects, 11 (25.6%) had cortisol below 5 μg/dl and low to normal ACTH levels, suggestive of secondary adrenal insufficiency. Two of the 11 subjects have confirmed central adrenal insufficiency and are on hydrocortisone replacement and/or stress dosing during illness; 3 had normal and 1 had subnormal cortisol response to ACTH low-dose stimulation test but has not yet been started on therapy; the remaining 5 have upcoming stimulation testing planned. Our findings suggest that patients with PMM2-CDG may be at risk for adrenal insufficiency. Monitoring of morning cortisol and ACTH levels should be part of the standard care in patients with PMM2-CDG.
- MeSH
- Adrenal Insufficiency diagnosis etiology physiopathology MeSH
- Child MeSH
- Adult MeSH
- Phosphotransferases (Phosphomutases) blood genetics MeSH
- Glycosylation MeSH
- Infant MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Child, Preschool MeSH
- Prospective Studies MeSH
- Risk Factors MeSH
- Pituitary-Adrenal System physiology MeSH
- Congenital Disorders of Glycosylation MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Infant MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Male MeSH
- Child, Preschool MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Observational Study MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
Cíl studie: Cílem studie bylo zavést metodu pro stanovení aktivity fosfomanomutázy 2 (PMM2) a kontrolního enzymu fosfo - manoizomerázy (PMI) v izolovaných lymfocytech a kultivovaných kožních fibroblastech a využít ji jako diferenciální diagnos - tický krok v souboru 18 pacientů s podezřením na CDG syndrom typu I. Typ studie: Původní práce. Název a sídlo pracoviště: Klinika dětského a dorostového lékařství, 1. lékařská fakulta Univerzity Karlovy a Všeobecná fakultní nemocnice v Praze. Materiál a metody: Analyzovaný soubor představuje 16 vzorků lymfocytů a 8 linií kultivovaných kožních fibroblastů od 18 pacientů z 15 nepříbuzných rodin, u kterých lékaři vyslovili vysoké podezření na CDG syndrom typu I. Kontrolní skupinu tvořilo 59 vzorků lymfocytů a 29 linií fibroblastů od pacientů, u kterých nebylo prokázáno podezření na metabolickou poruchu. Aktivity PMM2 a PMI byly měřeny spektrofotometricky při 37 °C jako redukce NADP + na NADPH při 340 nm. Výsledky: U PMM2 a PMI nebyly v lymfocytech ani kultivovaných fibroblastech nalezeny statisticky významné rozdíly aktivit v závislosti na věku či pohlaví. Aktivita PMM2 v lymfocytech u kontrolního souboru byla 0,34–2,58 nmol/min/mg (2,5% až 97,5% percentil) a ve fibroblastech 0,44–9,0 nmol/min/mg. Aktivita PMM2 v lymfocytech byla v souboru pacientů nízká (0,02–0,18 nmol/min/mg, mezikvartilové rozpětí, kontroly 0,73-1,42, p<0,001). Aktivita PMM2 ve fibroblastech od pacientů byla také nízká (0,2–0,66 nmol/min/mg; kontroly 1,06–3,17, p<0,001). Poměr PMM2/PMI byl u pacientů významně snížený v obou tkáních (p<0,001). U všech 18 pacientů byla diagnóza PMM2-CDG potvrzena i nálezem mutací v PMM2 genu. Závěr: Měření aktivity PMM2 v lymfocytech nebo kultivovaných fibroblastech umožňuje rychlé stanovení diagnózy PMM2- CDG, nejčastější dědičné poruchy glykosylace typu I
Objective: Aim of study was to establish a method for determining the activity of phosphomannomutase 2 (PMM2) and phosphomannose isomerase (PMI) as a control enzyme in isolated lymphocytes and cultured skin fibroblasts and use it as a differential diagnostic step in a group of 18 patients with suspected CDG syndrome type I. Design: Original paper. Settings: Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague Material and methods: Cohort of samples consists of 16 isolated lymphocytes and 8 cultured skin fibroblasts lines from 18 patients from 15 unrelated families with high clinical suspicion for CDG syndrome type I. Group of controls consisted of 59 lymphocytes and 29 fibroblasts cell lines from disease free patients. Activities PMM2 and PMI were measured spectrophotometrically at 37 °C as the reduction of NADP+ to NADPH at 340 nm. Results: Statistically significant correlation between activity of PMM2 and PMI and age or gender in lymphocytes or cul tured fibroblasts was not found. PMM2 activity in lymphocytes in the control group was from 0.34 to 2.58 nmol/min/mg (2.5% to 97.5% percentile) and in fibroblasts from 0.44 to 9.0 nmol/min/mg. PMM2 activity in lymphocytes in the group of patients was low (0.02-0.18 nmol/min/mg, interquartile range, controls 0.73-1.42 nmol/min/mg, p <0.001). PMM2 activity in fibroblasts from patients was also low (0.2-0.66 nmol/min/mg, controls 1.06-3.17 nmol/min/mg, p<0.001). PMM2 / PMI ratio in patients was significantly decreased in both tissues (p<0.001). The diagnosis of PMM2-CDG was confirmed by finding of mutations in PMM2 gene in all 18 patients. Conclusion: Measurement of PMM2 activity in lymphocytes or cultured fibroblasts allows to quickly diagnose PMM2-CDG, the most common congenital disorder of glycosylation.
- Keywords
- fosfomanomutáza (PMM2),
- MeSH
- Fibroblasts MeSH
- Glycosylation MeSH
- Humans MeSH
- Lymphocytes MeSH
- Mannose-6-Phosphate Isomerase * analysis MeSH
- Carbohydrate Metabolism MeSH
- Spectrophotometry MeSH
- Congenital Disorders of Glycosylation * diagnosis MeSH
- Check Tag
- Humans MeSH
- Publication type
- Clinical Study MeSH
We report on the seventh known patient with S-adenosylhomocysteine hydrolase (SAHH) deficiency presenting at birth with features resembling phosphomannomutase 2 (PMM2-CDG Ia) deficiency. Plasma methionine and total homocysteine levels were normal at 2 months and increased only after the 8th month of age. SAHH deficiency was confirmed at 4.5 years of age by showing decreased SAHH activity (11% in both erythrocytes and fibroblasts), and compound heterozygosity for a known mutation c.145C>T (p.R49C) and a novel variant c.211G>A (p.G71S) in the AHCY gene. Retrospective analysis of clinical features revealed striking similarities between SAHH deficiency and the PMM2-CDG Ia.
- MeSH
- Adenosylhomocysteinase deficiency genetics MeSH
- Diagnosis, Differential MeSH
- Erythrocytes enzymology pathology MeSH
- Fibroblasts enzymology pathology MeSH
- Phosphotransferases (Phosphomutases) deficiency MeSH
- Heterozygote MeSH
- Homocysteine blood MeSH
- Humans MeSH
- Methionine blood MeSH
- Mutation * MeSH
- Infant, Newborn MeSH
- Congenital Disorders of Glycosylation diagnosis MeSH
- Check Tag
- Humans MeSH
- Infant, Newborn MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Phosphomannomutase 2 (PMM2-CDG) is the most common congenital disorder of N-glycosylation and is caused by a deficient PMM2 activity. The clinical presentation and the onset of PMM2-CDG vary among affected individuals ranging from a severe antenatal presentation with multisystem involvement to mild adulthood presentation limited to minor neurological involvement. Management of affected patients requires a multidisciplinary approach. In this article, a systematic review of the literature on PMM2-CDG was conducted by a group of international experts in different aspects of CDG. Our managment guidelines were initiated based on the available evidence-based data and experts' opinions. This guideline mainly addresses the clinical evaluation of each system/organ involved in PMM2-CDG, and the recommended management approach. It is the first systematic review of current practices in PMM2-CDG and the first guidelines aiming at establishing a practical approach to the recognition, diagnosis and management of PMM2-CDG patients.
Cardiac involvement (CI) in phosphomannomutase 2-congenital disorders of glycosylation (PMM2-CDG) is part of the multisystemic presentation contributing to high mortality rates. The most common cardiac manifestations are pericardial effusion, cardiomyopathy, and structural heart defects. A genotype-phenotype correlation with organ involvement has not yet been described. We analyzed clinical, biochemical, and molecular genetic data of 222 patients from eight European centers and characterized the natural course of patients with CI. Fifty-seven patients (45 children) presented with CI, of whom 24 died (median age 21 months, standard deviation 49.8). Pericardial effusion was the most frequent manifestation (55.4%), occurring mostly within the first 6 months of life. The most common pathogenic variants in patients with CI were p.(Arg141His) in 74%, followed by p.(Val231Met) in 36%, which is 3.5 times higher than in PMM2-CDG patients without CI (p < 0.0001). Twenty-one out of 36 patients with p.(Val231Met) had CI; among them, 15 died, compared to 33 out of 166 patients without p.(Val231Met) who had CI (p < 0.0001). Nine out of 33 patients died (p = 0.0015), indicating greater clinical severity. Furthermore, the p.(Val231Met) variant is predominant in Eastern Europe, suggesting a founder effect. Cardiac complications in PMM2-CDG patients are common and serious. The variant p.(Val231Met) profoundly influences the extent of CI and mortality rates. Therefore, we recommend cardiac surveillance be included in the follow-up protocols for PMM2-CDG.
- MeSH
- Child MeSH
- Phenotype * MeSH
- Phosphotransferases (Phosphomutases) * genetics deficiency MeSH
- Genetic Association Studies MeSH
- Cardiomyopathies genetics MeSH
- Infant MeSH
- Humans MeSH
- Adolescent MeSH
- Mutation MeSH
- Infant, Newborn MeSH
- Child, Preschool MeSH
- Severity of Illness Index MeSH
- Congenital Disorders of Glycosylation * genetics MeSH
- Check Tag
- Child MeSH
- Infant MeSH
- Humans MeSH
- Adolescent MeSH
- Male MeSH
- Infant, Newborn MeSH
- Child, Preschool MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Multicenter Study MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Europe MeSH
Úvod: Deficit fosfomanomutázy 2 (PMM2-CDG) je nejčastějším typem poruch N-glykosylace s popsanými >900 pacienty. Onemocnění je autosomálně recesivně dědičné a biochemickou podstatou je porucha přeměny manóza-6-fosfátu na manóza-1-fosfát (M1P). Onemocnění se projevuje encefalopatií, neuropatií, typickou dysmorfií, atrofií mozečku a koagulopatií. Práce prezentuje výsledky klinických, biochemických a molekulárních vyšetření pacientů diagnostikovaných v ČR. Výsledky: Od roku 2002 bylo v ČR diagnostikováno 22 pacientů z 18 rodin. Dvě děti zemřely v kojeneckém věku. Věk žijících 20 pacientů je v rozpětí 9 měsíců až 29 let (medián 14 let). U všech pacientů je přítomný hypotonický a mozečkový syndrom, strabismus, deformity skeletu, koagulopatie a mentální retardace, která je v pásmu od lehkého až po hluboké postižení. U 94 % pacientů jsme prokázali atrofii mozečku. Typická dysmorfie (atypické rozložení tuku a vpáčení bradavek) byla zjištěna u 82 % dětí. U 9 pacientů se projevila epilepsie a 3 pacienti prodělali iktu podobné příhody. Isoelektrická fokusace transferinu v séru prokázala u všech pacientů zvýšené zastoupení nízkosialovaných forem. Diagnóza byla potvrzena enzymologicky detekcí snížené aktivity PMM2 v lymfocytech či fibroblastech a/nebo molekulárně-geneticky. V našem souboru pacientů bylo zastoupeno 10 mutací v genu PMM2, všichni pacienti jsou složení heterozygoti a 71 % mutovaných alel neslo jednu ze dvou prevalentních patogenních variant (c.422G>A, c.338C>T). Závěr: S ohledem na odhadovanou incidenci PMM2-CDG 1:20 000 se jedná o onemocnění v ČR poddiagnostikované. PMM2-CDG patří do diferenciální diagnostiky všech dětí s atrofií mozečku, a to i bez přítomnosti charakteristických dysmorfických rysů. V plánu je zařazení českých pacientů do prospektivní multicentrické mezinárodní studie hodnotící přirozený průběh onemocnění a eventuálně zařazení do klinické studie s novou experimentální léčebnou molekulou LipoM1P (manóza-1-fosfát inkorporovaná do liposomu).
Introduction: PMM2-CDG is the most common autosomal recessive N-glycosylation disorder with more than 900 patients described worldwide. It is caused by a deficiency of the phosphomannomutase 2 enzyme (PMM2) which catalyzes the second step of the mannose pathway, namely the conversion of mannose-6-phosphate to mannose-1-phosphate. The clinical presentation is characterised by encephalopathy, neuropathy, typical dysmorphism, cerebellar atrophy and coagulopathy. We present the results of clinical, biochemical and molecular analyses in patients diagnosed in the Czech Republic. Results: Since 2002, a total of 22 Czech patients from 18 families with PMM2 deficiency have been diagnosed. The age range of the patients spans from 9 months to 29 years with a median of 14 years, except two patients who died during infancy. Muscle hypotonia, intellectual disability of varying severity, strabismus, ataxia, bone deformities, and coagulopathy were observed in all patients. Cerebellar atrophy was documented in 94% of the investigated patients. The characteristic dysmorphism (inverted nipples and atypical fat pads) were present in 82% of the patients. Nine patients suffered from seizures, and three patients showed transient neurological deterioration after stroke-like episodes. In all the patients, increased amount of hypoglycosylated transferrin was found by isoelectric focusing. The diagnosis of the PMM2-CDG was confirmed at enzymatic and/or at molecular levels. Molecular analyses revealed that all patients are compound heterozygotes for a total of 10 different mutations in PMM2, and that 71% of our patients´ alleles have one of the two most frequent genetic variants (c.422G>A, c.338C>T). Conclusion: The estimated incidence of PMM2-CDG is 1:20,000, suggesting that this disorder is underdiagnosed in the Czech Republic. PMM2-CDG must be considered in differential diagnosis of patients with cerebellar atrophy even if they do not manifest characteristic dysmorphism. We plan to include our patients in a longitudinal international multicenter observational study and potentially the upcoming clinical trial with LipoM1P (lipomised mannose-1-phosphate).
- Keywords
- atrofie mozečku,
- MeSH
- Blood Coagulation Disorders, Inherited diagnosis pathology MeSH
- Child MeSH
- Adult MeSH
- Phosphotransferases (Phosphomutases) * deficiency MeSH
- Genetic Techniques MeSH
- Isoelectric Focusing MeSH
- Infant MeSH
- Humans MeSH
- Adolescent MeSH
- Cerebellum pathology MeSH
- Child, Preschool MeSH
- Retrospective Studies MeSH
- Congenital Disorders of Glycosylation * diagnosis complications physiopathology MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Infant MeSH
- Humans MeSH
- Adolescent MeSH
- Male MeSH
- Child, Preschool MeSH
- Female MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Východisko. Dědičné poruchy glykosylace proteinů způsobené poruchou tvorby N-glykanů představují rozsáhlou skupinu metabolických onemocnění, která se označuje jako syndrom CDG. V našem sdělení předkládáme výsledky klinických, metabolických a molekulárních vyšetření u dvou sourozenců s CDG syndromem typ Ia. Metody a výsledky. Asialované a nízkosialované transferiny v séru byly analyzovány pomocí turbidimetrické imunoeseje a izoelektrické fokusace. Gen pro fosfomannomutázu 2 (PMM2) byl studován cyklickým sekvenováním. Zvýšené zastoupení asialo- a nízkosialovaných transferinů v séru bylo zjištěno u dvou sourozenců s vpáčenými bradavkami, neprospíváním, strabismem, svalovou hypotonií, ataxií, epilepsií, mikrocefalií, hypoplazií mozečku a psychomotorickou retardací. Obě děti měly zvýšené aktivity aminotransferáz, arylsulfatázy A a β-glukuronidázy v séru a sníženou aktivitu α-mannosidázy v leukocytech. Obě děti měly sníženou koncentraci faktoru XI a proteinu S, jedno dítě mělo i sníženou koncentraci antitrombinu III a proteinu C. Molekulární analýzy ukázaly, že obě děti jsou „smíšení heterozygoti“ pro „missense mutace“ 422G>A a 357C>A v genu pro PMM 2 a současně i nositeli polymorfizmu IVS5+19 C→T v intronu za exonem 5 v homozygotní formě a polymorfizmem IVS5+22 T→A v heterozygotní formě. Závěry. Prognóza dětí se syndromem CDG Ia není příznivá. Skríninkovou metodou pro diagnostiku CDG syndromu je stanovení spektra sérových asialovaných a nízkosialovaných transferinů. Pro potvrzení diagnózy a upřesnění, o který typ onemocnění se jedná, jsou nutná enzymatická a/nebo molekulární vyšetření.
Backround. Congenital disorders of glycosylation (CDG syndrome) represent a newly delineated group of inherited diseases of glycoprotein synthesis. We present results of biochemical and molecular analyses in two Czech patients with CDG Ia syndrome. Methods andResults. Serumconcentrations of the nonglycosylated and hypoglycosylated transferrinweremeasured using turbidimetric immunoassay. In positive patients, the isoelectric focusing of serum transferrin and molecular analyses of the gene for phosphomannomutase 2 were performed. The disease manifested in both children in infancy with failure to thrive, inverted nipples, strabismus, epilepsy, muscle hypotonia, microcephaly, psychomotor retardation and hypoplasia of the cerebellum. The biochemical investigation revealed elevated liver enzymes, low concentration of factor XI and protein S. In one child lower concentration of the antithrombin III and protein C were found. Activities of arylsulfatase A and β-glucuronidase in serum were higher and activity of α-mannosidase in leucocytes was lower in comparison with controls. Molecular analyses revealed that both children are compound heterozygotes for the mutation 422G>A and 357C>A in gene for phosphomanomutase 2. Both siblings are also homozygotes for polymorfism IVS5+19 C →T and heterozygygotes for polymorfism IVS5+22 T→A. Conclusions, The prognosis of children with CDG Ia is unfavourable. Enzymatic and/or molecular studies are necessary for genetic counselling and the prenatal diagnosis.
- MeSH
- Child MeSH
- Adult MeSH
- Research Support as Topic MeSH
- Glycoproteins MeSH
- Glycosylation MeSH
- Clinical Laboratory Techniques statistics & numerical data MeSH
- Humans MeSH
- Cerebellar Diseases diagnosis genetics congenital MeSH
- Mass Screening methods MeSH
- Signs and Symptoms MeSH
- Metabolism, Inborn Errors diagnosis genetics MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Case Reports MeSH
- Review MeSH
- Comparative Study MeSH
Congenital disorders of glycosylation (CDG) are a rapidly growing family of genetic diseases with the phosphomannomutase 2 (PMM2)-CDG being the most common form of CDG. Most of these monogenic diseases are autosomal recessive and have multi-systemic manifestations, mainly psychomotor retardation, facial dysmorphisms, characteristic distribution of the fat pads, and variable coagulation abnormalities. The association of fetal hydrops with CDG has been reported, and pericardial effusion was also rarely observed in patients with PMM2-CDG. Here we describe an infant boy with PMM2-CDG. The diagnosis was suspected based on inverted nipples, fat pads, and combined coagulopathy. However, the primary symptom was progressive pericardial effusion leading to patient death at the age of 3 months. Screening for CDG performed by the use of isoelectric focusing of serum transferrin showed a typical PMM2-CDG pattern. Exome sequencing revealed one common pathogenic variant (c.691G > A/p.Val231Met) and one novel variant (c.447 + 3dupA) in the PMM2 gene. Both PMM2 variants were further confirmed by Sanger sequencing in both the proband and the parents' DNA. The novel variant was predicted to result in loss of donor splice site, and the analysis at mRNA level confirmed that it leads to exon five skipping (r.348_447del) and causes premature termination of translation to the protein (p.G117Kfs∗4), therefore is classified as likely pathogenic. Although there is no curative therapy for the PMM2-CDG at the moment, the other supportive care options are available to be offered. The definite diagnosis of PMM2-CDG can also assist in the process of genetic counseling, family planning, and preimplantation genetic diagnosis.
- Publication type
- Journal Article MeSH
PMM2-CDG is the most prevalent type of congenital disorders of glycosylation (CDG). It is caused by pathogenic variants in the gene encoding phosphomannomutase 2 (PMM2), which converts mannose-6-phosphate to mannose-1-phosphate and thus activates this saccharide for further glycosylation processes. Defective glycosylation can lead to an abnormal accumulation of unfolded proteins in endoplasmic reticulum (ER) and cause its stress. The ER is a key compartment for glycosylation, and its connection and communication with mitochondria has been described extensively in literature. Their crosstalk is important for cell proliferation, calcium homeostasis, apoptosis, mitochondrial fission regulation, bioenergetics, autophagy, lipid metabolism, inflammasome formation and unfolded protein response. Therefore, in the present study we posed a question, whether defective glycosylation leads to bioenergetic disruption. Our data reveal possible chronic stress in ER and activated unfolded protein response via PERK pathway in PMM2-CDG fibroblasts. Presumably, it leads to bioenergetic reorganization and increased assembly of respiratory chain complexes into supercomplexes together with suppressed glycolysis in PMM2-CDG patient cells. These changes cause alterations in Krebs cycle, which is tightly connected to electron transport system in mitochondria. In summary, we present data showing metabolic adaptation of cells to glycosylation defect caused by various pathogenic variants in PMM2.
