Intranasal oxytocin suppresses seizure-like behaviors in a mouse model of NGLY1 deficiency

NGLY1 deficiency is a genetic disease caused by biallelic mutations of the Ngly1 gene. Although epileptic seizure is one of the most severe symptoms in patients with NGLY1 deficiency, preclinical studies have not been conducted due to the lack of animal models for epileptic seizures in NGLY1 deficiency. Here, we observed the behaviors of male and female Ngly1-/- mice by video monitoring and found that these mice exhibit spontaneous seizure-like behaviors. Gene expression analyses and enzyme immunoassay revealed significant decreases in oxytocin, a well-known neuropeptide, in the hypothalamus of Ngly1-/- mice. Seizure-like behaviors in Ngly1-/- mice were transiently suppressed by a single intranasal administration of oxytocin. These findings suggest the therapeutic potential of oxytocin for epileptic seizure in patients with NGLY1 deficiency and contribute to the clarification of the disease mechanism.

"Hide and seek": Misleading transferrin variants in PMM2-CDG complicate diagnostics

PURPOSE

Congenital disorders of glycosylation (CDG) are one of the fastest growing groups of inborn errors of metabolism. Despite the availability of next-generation sequencing techniques and advanced methods for evaluation of glycosylation, CDG screening mainly relies on the analysis of serum transferrin (Tf) by isoelectric focusing, HPLC or capillary electrophoresis. The main pitfall of this screening method is the presence of Tf protein variants within the general population. Although reports describe the role of Tf variants leading to falsely abnormal results, their significance in confounding diagnosis in patients with CDG has not been documented so far. Here, we describe two PMM2-CDG cases, in which Tf variants complicated the diagnostic.

EXPERIMENTAL DESIGN

Glycosylation investigations included classical screening techniques (capillary electrophoresis, isoelectric focusing and HPLC of Tf) and various confirmation techniques (two-dimensional electrophoresis, western blot, N-glycome, UPLC-FLR/QTOF MS with Rapifluor). Tf variants were highlighted following neuraminidase treatment. Sequencing of PMM2 was performed.

RESULTS

In both patients, Tf screening pointed to CDG-II, while second-line analyses pointed to CDG-I. Tf variants were found in both patients, explaining these discrepancies. PMM2 causative variants were identified in both patients.

CONCLUSION AND CLINICAL RELEVANCE

We suggest that a neuraminidase treatment should be performed when a typical CDG Tf pattern is found upon initial screening analysis.

Coagulation abnormalities in a prospective cohort of 50 patients with PMM2-congenital disorder of glycosylation

BACKGROUND

Given the lack of reliable data on the prevalence of bleeding abnormalities and thrombotic episodes in PMM2-CDG patients, and whether coagulation abnormalities change over time, we prospectively collected and reviewed natural history data. Patients with PMM2-CDG often have abnormal coagulation studies due to glycosylation abnormalities but the frequency of complications resulting from these has not been prospectively studied.

METHODS

We studied fifty individuals enrolled in the Frontiers in Congenital Disorders of Glycosylation Consortium (FCDGC) natural history study with molecularly confirmed diagnosis of PMM2-CDG. We collected data on prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), platelets, factor IX activity (FIX), factor XI activity (FXI), protein C activity (PC), protein S activity (PS) and antithrombin activity (AT).

RESULTS

Prothrombotic and antithrombotic factor activities were frequently abnormal in PMM2-CDG patients, including AT, PC, PT, INR, and FXI. AT deficiency was the most common abnormality in 83.3% of patients. AT activity was below 50% in 62.5% of all patients (normal range 80-130%). Interestingly, 16% of the cohort experienced symptoms of spontaneous bleeding and 10% had thrombosis. Stroke-like episodes (SLE) were reported in 18% of patients in our cohort. Based on the linear growth models, on average, patients did not show significant change in AT (n = 48; t(23.8) = 1.75, p = 0.09), FIX (n = 36; t(61) = 1.60, p = 0.12), FXI (n = 39; t(22.8) = 1.88, p = 0.07), PS (n = 25; t(28.8) = 1.08, p = 0.29), PC (n = 38; t(68) = 1.61, p = 0.11), INR (n = 44; t(184) = -1.06, p = 0.29), or PT (n = 43; t(192) = -0.69, p = 0.49) over time. AT activity positively correlated with FIX activity. PS activity was significantly lower in males.

CONCLUSION

Based on our natural history data and previous literature, we conclude that caution should be exercised when the AT levels are lower than 65%, as most thrombotic events occur in patients with AT below this level. All five, male PMM2-CDG patients in our cohort who developed thrombosis had abnormal AT levels, ranging between 19% and 63%. Thrombosis was associated with infection in all cases. We did not find significant change in AT levels over time. Several PMM2-CDG patients had an increased bleeding tendency. More long-term follow-up is necessary on coagulation abnormalities and the associated clinical symptoms to provide guidelines for therapy, patient management, and appropriate counseling.

SYNOPSIS

Most PMM2-CDG patients display chronic coagulation abnormalities without significant improvement, associated with a frequency of 16% clinical bleeding abnormalities, and 10% thrombotic episodes in patients with severe antithrombin deficiency.

Liver transplantation recovers hepatic N-glycosylation with persistent IgG glycosylation abnormalities: Three-year follow-up in a patient with phosphomannomutase-2-congenital disorder of glycosylation

Phosphomannomutase-2-congenital disorder of glycosylation (PMM2-CDG) is the most common CDG and presents with highly variable features ranging from isolated neurologic involvement to severe multi-organ dysfunction. Liver abnormalities occur in in almost all patients and frequently include hepatomegaly and elevated aminotransferases, although only a minority of patients develop progressive hepatic fibrosis and liver failure. No curative therapies are currently available for PMM2-CDG, although investigation into several novel therapies is ongoing. We report the first successful liver transplantation in a 4-year-old patient with PMM2-CDG. Over a 3-year follow-up period, she demonstrated improved growth and neurocognitive development and complete normalization of liver enzymes, coagulation parameters, and carbohydrate-deficient transferrin profile, but persistently abnormal IgG glycosylation and recurrent upper airway infections that did not require hospitalization. Liver transplant should be considered as a treatment option for PMM2-CDG patients with end-stage liver disease, however these patients may be at increased risk for recurrent bacterial infections post-transplant.

Phosphoglucomutase-1 deficiency: Early presentation, metabolic management and detection in neonatal blood spots

Phosphoglucomutase 1 deficiency is a congenital disorder of glycosylation (CDG) with multiorgan involvement affecting carbohydrate metabolism, N-glycosylation and energy production. The metabolic management consists of dietary D-galactose supplementation that ameliorates hypoglycemia, hepatic dysfunction, endocrine anomalies and growth delay. Previous studies suggest that D-galactose administration in juvenile patients leads to more significant and long-lasting effects, stressing the urge of neonatal diagnosis (0-6 months of age). Here, we detail the early clinical presentation of PGM1-CDG in eleven infantile patients, and applied the modified Beutler test for screening of PGM1-CDG in neonatal dried blood spots (DBSs). All eleven infants presented episodic hypoglycemia and elevated transaminases, along with cleft palate and growth delay (10/11), muscle involvement (8/11), neurologic involvement (5/11), cardiac defects (2/11). Standard dietary measures for suspected lactose intolerance in four patients prior to diagnosis led to worsening of hypoglycemia, hepatic failure and recurrent diarrhea, which resolved upon D-galactose supplementation. To investigate possible differences in early vs. late clinical presentation, we performed the first systematic literature review for PGM1-CDG, which highlighted respiratory and gastrointestinal symptoms as significantly more diagnosed in neonatal age. The modified Butler-test successfully identified PGM1-CDG in DBSs from seven patients, including for the first time Guthrie cards from newborn screening, confirming the possibility of future inclusion of PGM1-CDG in neonatal screening programs. In conclusion, severe infantile morbidity of PGM1-CDG due to delayed diagnosis could be prevented by raising awareness on its early presentation and by inclusion in newborn screening programs, enabling early treatments and galactose-based metabolic management.

A novel phosphoglucomutase-deficient mouse model reveals aberrant glycosylation and early embryonic lethality

Patients with phosphoglucomutase (PGM1) deficiency, a congenital disorder of glycosylation (CDG) suffer from multiple disease phenotypes. Midline cleft defects are present at birth. Overtime, additional clinical phenotypes, which include severe hypoglycemia, hepatopathy, growth retardation, hormonal deficiencies, hemostatic anomalies, frequently lethal, early-onset of dilated cardiomyopathy and myopathy emerge, reflecting the central roles of the enzyme in (glycogen) metabolism and glycosylation. To delineate the pathophysiology of the tissue-specific disease phenotypes, we constructed a constitutive Pgm2 (mouse ortholog of human PGM1)-knockout (KO) mouse model using CRISPR-Cas9 technology. After multiple crosses between heterozygous parents, we were unable to identify homozygous life births in 78 newborn pups (P = 1.59897E-06), suggesting an embryonic lethality phenotype in the homozygotes. Ultrasound studies of the course of pregnancy confirmed Pgm2-deficient pups succumb before E9.5. Oral galactose supplementation (9 mg/mL drinking water) did not rescue the lethality. Biochemical studies of tissues and skin fibroblasts harvested from heterozygous animals confirmed reduced Pgm2 enzyme activity and abundance, but no change in glycogen content. However, glycomics analyses in serum revealed an abnormal glycosylation pattern in the Pgm2^+/- animals, similar to that seen in PGM1-CDG.

Factor VIII and vWF deficiency in STT3A-CDG

STT3A-CDG (OMIM# 615596) is an autosomal recessive N-linked glycosylation disorder characterized by seizures, developmental delay, intellectual disability, and a type I carbohydrate deficient transferrin pattern. All previously reported cases (n = 6) have been attributed to a homozygous pathogenic missense variant c.1877C>T (p.Val626Ala) in STT3A. We describe a patient with a novel homozygous likely pathogenic missense variant c.1079A>C (p.Tyr360Ser) who presents with chronically low Factor VIII (FVIII) and von Willebrand Factor (vWF) levels and activities in addition to the previously reported symptoms of developmental delay and seizures. VWF in our patient's plasma is present in a mildly hypoglycosylated form. FVIII antigen levels were too low to quantify in our patient. Functional studies with STT3A^-/- HEK293 cells showed severely reduced FVIII antigen and activity levels in conditioned media <10% expected, but normal intracellular levels. We also show decreased glycosylation of STT3A-specific acceptors in fibroblasts from our patient, providing a mechanistic explanation for how STT3A deficiency leads to a severe defect in FVIII secretion. Our results suggest that certain STT3A-dependent N-glycans are required for efficient FVIII secretion, and the decreased FVIII level in our patient is a combined effect of both severely impaired FVIII secretion and lower plasma VWF level. Our report expands both the genotype and phenotype of STT3A-CDG; demonstrating, as in most types of CDG, that there are multiple disease-causing variants in STT3A.

Unexplained death in patients with NGLY1 mutations may be explained by adrenal insufficiency

Homozygous mutations in NGLY1 were recently found to cause a condition characterized by a complex neurological syndrome, hypo- or alacrimia, and elevated liver transaminases. For yet unknown reasons, mortality is increased in patients with this condition. NGLY1 encodes the cytosolic enzyme N-glycanase 1, which is responsible for the deglycosylation of misfolded N-glycosylated proteins. Disruption of this process is hypothesized to lead to an accumulation of misfolded proteins in the cytosol. Here, we describe the disease course of a girl with a homozygous mutation in NGLY1, namely c.1837del (p.Gln613 fs). In addition to the previously described symptoms, at the age of 8 she presented with recurrent infections and hyperpigmentation, and, subsequently, a diagnosis of primary adrenal insufficiency was made. There are no previous reports describing adrenal insufficiency in such patients. We postulate that patients with NGLY1 deficiency may develop adrenal insufficiency as a consequence of impaired proteostasis, and the accompanying proteotoxic stress-induced cell death, through defective Nrf1 function. We recommend an annual evaluation of adrenal function in all patients with NGLY1 mutations in order to prevent unnecessary deaths.

CCDC115-CDG: A new rare and misleading inherited cause of liver disease

Congenital disorders of glycosylation (CDG) linked to defects in Golgi apparatus homeostasis constitute an increasing part of these rare inherited diseases. Among them, COG-CDG, ATP6V0A2-CDG, TMEM199-CDG and CCDC115-CDG have been shown to disturb Golgi vesicular trafficking and/or lumen pH acidification. Here, we report 3 new unrelated cases of CCDC115-CDG with emphasis on diagnosis difficulties related to strong phenotypic similarities with mitochondriopathies, Niemann-Pick disease C and Wilson Disease. Indeed, while two individuals clinically presented with early and severe liver fibrosis and cirrhosis associated with neurological symptoms, the other one "only" showed isolated and late severe liver involvement. Biological results were similar to previously described patients, including hypercholesterolemia, elevated alkaline phosphatases and defects in copper metabolism. CDG screening and glycosylation study finally led to the molecular diagnosis of CCDC115-CDG. Besides pointing to the importance of CDG screening in patients with unexplained and severe liver disease, these reports expand the clinical and molecular phenotypes of CCDC115-CDG. The hepatic involvement is particularly addressed. Furthermore, hypothesis concerning the pathogenesis of the liver disease and of major biological abnormalities are proposed.

Cardiac complications of congenital disorders of glycosylation (CDG): a systematic review of the literature

Congenital disorders of glycosylation (CDG) are inborn errors of metabolism due to protein and lipid hypoglycosylation. This rapidly growing family of genetic diseases comprises 103 CDG types, with a broad phenotypic diversity ranging from mild to severe poly-organ -system dysfunction. This literature review summarizes cardiac involvement, reported in 20% of CDG. CDG with cardiac involvement were divided according to the associated type of glycosylation: N-glycosylation, O-glycosylation, dolichol synthesis, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, COG complex, V-ATPase complex, and other glycosylation pathways. The aim of this review was to document and interpret the incidence of heart disease in CDG patients. Heart disorders were grouped into cardiomyopathies, structural defects, and arrhythmogenic disorders. This work may contribute to improved early management of cardiac complications in CDG.

Key features and clinical variability of COG6-CDG

The conserved oligomeric Golgi (COG) complex consists of eight subunits and plays a crucial role in Golgi trafficking and positioning of glycosylation enzymes. Mutations in all COG subunits, except subunit 3, have been detected in patients with congenital disorders of glycosylation (CDG) of variable severity. So far, 3 families with a total of 10 individuals with biallelic COG6 mutations have been described, showing a broad clinical spectrum. Here we present 7 additional patients with 4 novel COG6 mutations. In spite of clinical variability, we delineate the core features of COG6-CDG i.e. liver involvement (9/10), microcephaly (8/10), developmental disability (8/10), recurrent infections (7/10), early lethality (6/10), and hypohidrosis predisposing for hyperthermia (6/10) and hyperkeratosis (4/10) as ectodermal signs. Regarding all COG6-related disorders a genotype-phenotype correlation can be discerned ranging from deep intronic mutations found in Shaheen syndrome as the mildest form to loss-of-function mutations leading to early lethal CDG phenotypes. A comparison with other COG deficiencies suggests ectodermal changes to be a hallmark of COG6-related disorders. Our findings aid clinical differentiation of this complex group of disorders and imply subtle functional differences between the COG complex subunits.

Skin manifestations in CDG

The group of congenital disorders of glycosylation (CDG) has expanded tremendously since its first description in 1980, with around 70 distinct disorders described to date. A great phenotypic variability exists, ranging from multisystem disease to single organ involvement. Skin manifestations, although inconsistently present, are part of this broad clinical spectrum. Indeed, the presence of inverted nipples, fat pads and orange peel skin in a patient with developmental delay are considered as a hallmark of CDG, particularly seen in PMM2 deficiency. However, over the years many more dermatological findings have been observed (e.g., ichthyosis, cutis laxa, tumoral calcinosis…). In this review we will discuss the variety of skin manifestations reported in CDG. Moreover, we will explore the possible mechanisms that link a certain glycosylation deficiency to its skin phenotype.

Galactose supplementation in phosphoglucomutase-1 deficiency; review and outlook for a novel treatable CDG

We recently redefined phosphoglucomutase-1 deficiency not only as an enzyme defect, involved in normal glycogen metabolism, but also an inborn error of protein glycosylation. Phosphoglucomutase-1 is a key enzyme in glycolysis and glycogenesis by catalyzing in the bidirectional transfer of phosphate from position 1 to 6 on glucose. Glucose-1-P and UDP-glucose are closely linked to galactose metabolism. Normal PGM1 activity is important for effective glycolysis during fasting. Activated glucose and galactose are essential for normal protein glycosylation. The complex defect involving abnormal concentrations of activated sugars leads to hypoglycemia and two major phenotypic presentations, one with primary muscle involvement and the other with severe multisystem disease. The multisystem phenotype includes growth delay and malformations, like cleft palate or uvula, and liver, endocrine and heart function with possible cardiomyopathy. The patients have normal intelligence. Decreased transferrin galactosylation is a characteristic finding on mass spectrometry. Previous in vitro studies in patient fibroblasts showed an improvement of glycosylation on galactose supplements. Four patients with PGM1 deficiency have been trialed on d-galactose (compassionate use), and showed improvement of serum transferrin hypoglycosylation. There was a parallel improvement of liver function, endocrine abnormalities and a decrease in the frequency of hypoglycemic episodes. No side effects have been observed. Galactose supplementation didn't seem to resolve all clinical symptoms. Adding complex carbohydrates showed an additional clinical amelioration. Based on the available clinical data we suggest to consider the use of 0.5-1g/kg/day d-galactose and maximum 50 g/day oral galactose therapy in PGM1-CDG. The existing data on galactose therapy have to be viewed as preliminary observations. A prospective multicenter trial is ongoing to evaluate the efficacy and optimal d-galactose dose of galactose supplementation.

Congenital disorders of glycosylation with neonatal presentation

Congenital disorders of glycosylation (CDG) are a group of hereditary diseases characterised by deficiency of enzymes involved in proteins glycosylation. We describe the clinical case of a neonate with CDG type 1a, nowadays designated phosphomannomutase 2 (PMM2)-CDG. Physical examination showed an abnormal facies, axial hypotonia, abnormal fat distribution, inverted nipples, non-palpable testicles and arachnodactyly. Progressive multiple system organ involvement and worsening of hypertrophic cardiomyopathy occurred. Metabolic study revealed a CDG disturbance, which was confirmed by genetic study. The following mutations were identified: c.193G>T; p.D65Y and c.470T>C; p.F157S. Clinical deterioration was inevitable with multisystemic failure and death. CDG represents a challenge for physicians due to multiple organ involvement, and heterogeneous clinical manifestations. The neonatal form is usually associated with the worst prognosis.

Severe, fatal multisystem manifestations in a patient with dolichol kinase-congenital disorder of glycosylation

Congenital disorders of glycosylation are a group of metabolic disorders with an expansive and highly variable clinical presentation caused by abnormal glycosylation of proteins and lipids. Dolichol kinase (DOLK) catalyzes the final step in biosynthesis of dolichol phosphate (Dol-P), which is the oligosaccharide carrier required for protein N-glycosylation. Human DOLK deficiency, also known as DOLK-CDG or CDG-Im, results in a syndrome that has been reported to manifest with dilated cardiomyopathy of variable severity. A male neonate born to non-consanguineous parents of Palestinian origin presented with dysmorphic features, genital abnormalities, talipes equinovarus, and severe, refractory generalized seizures. Additional multi-systemic manifestations developed including dilated cardiomyopathy, hepatomegaly, severe insulin-resistant hyperglycemia, and renal failure, which were ultimately fatal at age 9months. Electrospray ionization mass spectrometric (ESI-MS) analysis of transferrin identified a type I congenital disorder of glycosylation; next-generation sequencing demonstrated homozygous p.Q483K DOLK mutations that were confirmed in patient fibroblasts to result in severely reduced substrate binding and catalytic activity. This patient expands the phenotype of DOLK-CDG to include anatomic malformations and multi-systemic dysfunction.

Retinal characteristics of the congenital disorder of glycosylation PMM2-CDG

The congenital disorder of glycosylation, PMM2-CDG, is associated with progressive photoreceptor degeneration, which causes a pigmentary retinopathy. We identified a sibling pair, mildly affected with PMM2-CDG, who showed preserved photoreceptor function, but profound deficits of the 'on-pathway' in the retina. This localises the site of early, or initial, retinal dysfunction in PMM2-CDG to the synapse in the outer plexiform layer between bipolar cells, photoreceptors and horizontal cells. We sought wider evidence to support this novel finding by reviewing retrospectively the case notes of eight patients, diagnosed with PMM2-CDG between the ages of 7 months to 16 years. We compared the clinical presentation and electroretinograms, (ERGs), of these patients with the sibling pair. We found that five of eight patients showed characteristic ERG features of on-pathway dysfunction in the form of reduced ERG b-wave amplitude. The remaining three patients had significant photoreceptor dysfunction by the time of ERG recording, and both a- and b-wave amplitudes were markedly attenuated. We conclude that ERG signs of on-pathway dysfunction can be detected in the early stages of PMM2-CDG. Referral for electroretinography evidence of this specific on-pathway deficit, with preservation of oscillatory potentials, can help establish the diagnosis of infants with developmental delay or failure to thrive in whom a glycosylation defect is suspected. Also by increasing our understanding of the interaction of N-glycoproteins at this synapse we may be able to design future therapeutic intervention to prevent or ameliorate the progressive visual loss associated with PMM2-CDG.

Thrombotic complications in patients with PMM2-CDG

Many proteins regulating coagulation, including factor IX, factor XI, Antithrombin-III, Protein C and Protein S are deficient or decreased in activity in congenital disorders of glycosylation (CDG). Because of the imbalance of coagulation and anticoagulation factors, some patients develop acute vascular events, such as thrombosis. Identifying patients with increased risk for thrombotic events could prevent serious complications and even mortality. We performed a systematic review on patients diagnosed with the most common CDG form; PMM2-CDG, reported between 1990 and 2012 in medical literature. We also evaluated our PMM2-CDG patient-cohort of 15 patients. In total, based on the availability of comprehensive clinical descriptions, 100 patients were included in the study. Patients with and without thrombotic events were compared based on the alterations of the following glycosylated coagulation and anticoagulation factors: Antithrombin-III, Protein C, Protein S, factors IX and XI. We also assessed the global hemostasis, family history and provoking events. In the group of 100 PMM2-CDG patients 14 had suffered a venous or arterial thrombotic event. Low activity of several anticoagulation factors correlated with thrombotic events. Relatively high factor IX and XI activities were not associated with thrombosis. Prolonged PT and aPTT did not seem to protect against thrombosis in patients. Surgical procedures were frequently associated with thrombotic events. Based on the association of thrombosis and surgery in PMM2-CDG we advise to avoid elective surgical procedures in PMM2-CDG patients. Easily preventable risk factors like immobility should be treated with regular physiotherapy. We suggest a yearly follow-up for Antithrombin-III and Protein C levels and parent education for early thrombotic signs in CDG.

A novel congenital disorder of glycosylation type without central nervous system involvement caused by mutations in the phosphoglucomutase 1 gene

Recent years have seen great advances in our knowledge of congenital disorders of glycosylation (CDG), a clinically and biochemically heterogeneous group of genetic diseases caused by defects in the synthesis (CDG-I) or processing (CDG-II) of glycans that form glycoconjugates. This paper reports a new subtype of non-neurological CDG involving the impaired cytoplasmic biosynthesis of nucleotide sugars needed for glycan biosynthesis. A patient presented with muscle fatigue, elevated creatine kinase, growth hormone deficiency, and first branchial arch syndrome. These findings, together with the abnormal type II plasma transferrin isoform profile detected, was compatible with a CDG. Functional testing and clinical analyses suggested a deficiency in the interconversion of glucose-1-phosphate and glucose-6-phosphate catalyzed by phosphoglucomutase (PGM1), a defect previously described as glycogenosis type XIV (GSDXIV, MIM 612934). PGM1 activity in patient-derived fibroblasts was significantly reduced, as was the quantity of immunoreactive PGM1 protein (Western blot assays). Mutation analysis of PGM1 and subsequent functional analysis investigating transient expression of PGM1 in immortalized patient fibroblasts, followed by ex vivo splicing assays using minigenes, allowed the characterization of two novel pathogenic mutations: c.871G>A (p.Gly291Arg) and c.1144 + 3A>T. The latter represents a severe splicing mutation leading to the out-of-frame skipping of exon 7 and the formation of a truncated protein (p.Arg343fs). MALDI mass spectra of permethylated protein N-glycans from the patient's serum suggested a marked hypoglycosylation defect. The present findings confirm that, in addition to a rare muscular glycolytic defect, PGM1 deficiency causes a non-neurological disorder of glycosylation.

From discrete dilated cardiomyopathy to successful cardiac transplantation in congenital disorders of glycosylation due to dolichol kinase deficiency (DK1-CDG)

Congenital disorders of glycosylation are a growing group of inborn errors of protein glycosylation. Cardiac involvement is frequently observed in the most common form, PMM2-CDG, especially hypertrophic cardiomyopathy. Dilated cardiomyopathy, however, has been only observed in a few CDG subtypes, usually with a lethal outcome. We report on cardiac pathology in nine patients from three unrelated Israeli families, diagnosed with dolichol kinase deficiency, due to novel, homozygous DK1 gene mutations. The cardiac symptoms varied from discrete, mild dilation to overt heart failure with death. Two children died unexpectedly with acute symptoms of heart failure before the diagnosis of DK1-CDG and heart transplantation could take place. Three other affected children with mild dilated cardiomyopathy at the time of the diagnosis deteriorated rapidly, two of them within days after an acute infection. They all went through successful heart transplantation; one died unexpectedly and 2 others are currently (after 1-5 years) clinically stable. The other 4 children diagnosed with mild dilated cardiomyopathy are doing well on supportive heart failure therapy. In most cases, the cardiac findings dominated the clinical picture, without central nervous system or multisystem involvement, which is unique in CDG syndrome. We suggest to test for DK1-CDG in patients with dilated cardiomyopathy. Patients with discrete cardiomyopathy may remain stable on supportive treatment while others deteriorate rapidly. Our paper is the first comprehensive study on the phenotype of DK1-CDG and the first successful organ transplantation in CDG syndrome.

Hypertrophic cardiomyopathy with cardiac rupture and tamponade caused by congenital disorder of glycosylation type Ia

Hypertrophic cardiomyopathy (HCM) is a rare presenting feature of congenital disorder of glycosylation type Ia (CDG-Ia). We report two female siblings with CDG-Ia and cardiomyopathy. Patient no. 1 died at 12 days of age from cardiac rupture and tamponade, which has not previously been reported in CDG-Ia. The second patient died at 2 months of age from HCM. The severe cardiac manifestations seen in our patients emphasize the importance of early cardiac assessment in all patients with CDG-Ia.

Metabolic cutis laxa syndromes

Cutis laxa is a rare skin disorder characterized by wrinkled, redundant, inelastic and sagging skin due to defective synthesis of elastic fibers and other proteins of the extracellular matrix. Wrinkled, inelastic skin occurs in many cases as an acquired condition. Syndromic forms of cutis laxa, however, are caused by diverse genetic defects, mostly coding for structural extracellular matrix proteins. Surprisingly a number of metabolic disorders have been also found to be associated with inherited cutis laxa. Menkes disease was the first metabolic disease reported with old-looking, wrinkled skin. Cutis laxa has recently been found in patients with abnormal glycosylation. The discovery of the COG7 defect in patients with wrinkled, inelastic skin was the first genetic link with the Congenital Disorders of Glycosylation (CDG). Since then several inborn errors of metabolism with cutis laxa have been described with variable severity. These include P5CS, ATP6V0A2-CDG and PYCR1 defects. In spite of the evolving number of cutis laxa-related diseases a large part of the cases remain genetically unsolved. In metabolic cutis laxa syndromes the clinical and laboratory features might partially overlap, however there are some distinct, discriminative features. In this review on metabolic diseases causing cutis laxa we offer a practical approach for the differential diagnosis of metabolic cutis laxa syndromes.

Clinical and molecular studies of EXT1/EXT2 in Bulgaria

EXT1/EXT2-CDG (Multiple cartilagineous exostoses, hereditary multiple osteochondroma (MO); OMIM 133700/133701) are common defects of O-xylosylglycan glycosylation. The diagnostic criteria are at least two osteochondromas of the juxta-epiphyseal region of long bones with in the majority of cases a positive family history and/or mutation in one of the EXT genes. The authors report data on clinical symptoms and complications of 23 patients (from 16 families), discussing the family history, age of diagnosis, new clinical and molecular data. Fifteen mutations and large deletions, of which nine are new, were detected in the EXT1 and EXT2 gene by sequence analysis, FISH and MLPA analysis.

RFT1-CDG: deafness as a novel feature of congenital disorders of glycosylation

Congenital disorders of glycosylation (CDG) are genetic diseases due to defects in the synthesis of glycans and in the attachment of glycans to lipids and proteins. Actually, some 42 CDG are known including defects in protein N-glycosylation, in protein O-glycosylation, in lipid glycosylation, and in multiple and other glycosylation pathways. Most CDG are multisystem diseases and a large number of signs and symptoms have already been reported in CDG. An exception to this is deafness. This symptom has not been observed as a consistent feature in CDG. In 2008, a novel defect was identified in protein N-glycosylation, namely in RFT1. This is a defect in the assembly of N-glycans. RFT1 is involved in the transfer of Man(5)GlcNAc(2)-PP-Dol from the cytoplasmic to the luminal side of the endoplasmic reticulum. According to the novel nomenclature (non-italicized gene symbol followed by -CDG) this defect is named RFT1-CDG. Recently, three other patients with RFT1-CDG have been reported and here we report two novel patients. Remarkably, all six patients with RFT1-CDG show sensorineural deafness as part of a severe neurological syndrome. We conclude that RFT1-CDG is the first 'deafness-CDG'. CDG should be included in the work-up of congenital, particularly syndromic, hearing loss.

Congenital disorder of glycosylation type Ia: heterogeneity in the clinical presentation from multivisceral failure to hyperinsulinaemic hypoglycaemia as leading symptoms in three infants with phosphomannomutase deficiency

We describe three patients with congenital disorder of glycosylation (CDG) type Ia, all of whom had persistent hyperinsulinaemic hypoglycaemia responding to diazoxide therapy as a common feature. The first patient, an infant girl, presented with recurrent vomiting, failure to thrive, liver impairment, hypothyroidism and a pericardial effusion. The second patient, also female, had a milder disease with single organ involvement, presenting as isolated hyperinsulinaemic hypoglycaemia, not associated with any cognitive impairment. The third patient, a boy presented with multi-organ manifestations including congenital hypothyroidism, persistent hyperinsulinaemic hypoglycaemia, coagulopathy, olivopontocerebellar hypoplasia and recurrent pancreatitis. All three patients had a type 1 serum transferrin isoform pattern, and were subsequently found to have low phosphomannomutase activity, confirming the diagnosis of CDG type Ia. Our findings emphasize that CDG should be considered as a differential diagnosis in patients with persistent hyperinsulinaemic hypoglycaemia and that it may even occasionally be the leading symptom in CDG Ia.

Cardiomyopathy in the congenital disorders of glycosylation (CDG): a case of late presentation and literature review

The congenital disorders of glycosylation (CDG) are a recently described group of inherited multisystem disorders characterized by defects predominantly of N- and O-glycosylation of proteins. Cardiomyopathy in CDG has previously been described in several subtypes; it is usually associated with high morbidity and mortality and the majority of cases present in the first 2 years of life. This is the first case with presentation in late childhood and the article reviews current literature. An 11-year-old female with a background of learning difficulties presented in cardiac failure secondary to severe dilated cardiomyopathy. Prior to the diagnosis of CDG, her condition deteriorated; she required mechanical support (Excor Berlin Heart) and was listed for cardiac transplant. Investigations included screening for glycosylation disorders, and isoelectric focusing of transferrin revealed an abnormal type 1 pattern. Analysis of phosphomannomutase and phosphomannose isomerase showed normal enzyme activity, excluding PMM2 (CDG Ia) and MPI (CDG Ib). Lipid-linked oligosaccharide and mutational studies have not yet defined the defect. Despite aggressive therapy there were persistent difficulties achieving adequate anticoagulation and she developed multiple life-threatening thrombotic complications. She was removed from the transplant list and died from overwhelming sepsis 5 weeks following admission. This case emphasizes the need to screen all children with an undiagnosed cardiomyopathy for CDG, regardless of age, and where possible to exclude CDG before the use of cardiac bridging devices. It highlights the many practical and ethical challenges that may be encountered where clinical knowledge and experience are still evolving.

Comprehensive description of the phenotype of the first case of congenital disorder of glycosylation due to RFT1 deficiency (CDG In)

Very recently, Haeuptle and colleagues described a new glycosylation defect due to RFT1 deficiency (CDG In). Accumulation of intracellular DolPP-GlcNAc(2)Man(5) with absence of cytosolic GlcNAc(2)Man(5) resembled the profile of a yeast mutant deficient in RFT1, a protein that is thought to have a role as a flippase. This is the first detailed description of the clinical phenotype of this patient. It was a severe disorder affecting intrauterine development and movement, and leading to intrauterine growth retardation. The child was born with several musculoskeletal abnormalities including arthrogryposis. Postnatally, severe reflux and irregular bowl movements contributed to failure to thrive. The patient showed very little development and no vision and suffered from drug-resistant epilepsy. Abnormal coagulation resulted in thrombosis and the patient died at the age of 4 years from a pulmonary embolus.

Congenital disorder of glycosylation type Id (CDG Id): phenotypic, biochemical and molecular characterization of a new patient

Congenital disorders of glycosylation (CDG) are a family of multisystem inherited disorders caused by defects in the biosynthesis of N- or O-glycans. Among the many different subtypes of CDG, the defect of a mannosyltransferase encoded by the human ALG3 gene (chromosome 3q27) is known to cause CDG Id. Six patients with CDG Id have been described in the literature so far. We further delineate the clinical, biochemical, neuroradiological and molecular features of CDG Id by reporting an additional patient bearing a novel missense mutation in the ALG3 gene. All patients with CDG Id display a slowly progressive encephalopathy with microcephaly, severe psychomotor retardation and epileptic seizures. They also share some typical dysmorphic features but they do not present the multisystem involvement observed in other CDG syndromes or any biological marker abnormalities. Unusually marked osteopenia is a feature in some patients and may remain undiagnosed until revealed by pathological fractures. Serum transferrin screening for CDG should be extended to all patients with encephalopathy of unknown origin, even in the absence of multisystem involvement.

Long-standing mild hypertransaminasaemia caused by congenital disorder of glycosylation (CDG) type IIx

A 32 year-old asymptomatic male came to our attention with a 21-year history, documented elsewhere, of puzzling increases in his serum transaminase level. At first, very low serum ceruloplasmin level suggested Wilson disease. Two liver biopsies showed mild portal inflammation, steatosis and mild fibrosis. Further investigation revealed low levels of the glycoproteins AT III and clotting factor XI, leading to a diagnosis of congenital disorder of glycosylation (CDG) type II. Further studies as to the cause of this 'apparently new' CDG, are ongoing. On the basis of our data and a literature review, we suggest that subjects with asymptomatic hypertransaminasaemia be screened for CDG.

Congenital disorder of glycosylation type Ix: review of clinical spectrum and diagnostic steps

Congenital disorder of glycosylation type I (CDG I) represent a rapidly growing group of inherited multisystem disorders with 13 genetically established subtypes (CDG Ia to CDG Im), and a high number of biochemically unresolved cases (CDG Ix). Further diagnostic effort and prognosis counselling are very challenging in these children. In the current study, we reviewed the clinical records of 10 CDG Ix patients and compared the data with 13 CDG Ix patients published in the literature in search for specific symptoms to create clinical subgroups. The most frequent findings were rather nonspecific, including developmental delay and axial hypotonia. Several features were found that are uncommon in CDG syndrome, such as elevated creatine kinase or arthrogryposis. Distinct ophthalmological abnormalities were observed including optic nerve atrophy, cataract and glaucoma. Two subgroups could be established: one with a pure neurological presentation and the other with a neurological-multivisceral form. The first group had a significantly better prognosis. The unique presentation of microcephaly, seizures, ascites, hepatomegaly, nephrotic syndrome and severe developmental delay was observed in one child diagnosed with CDG Ik. Establishing clinical subgroups and increasing the number of patients within the subgroups may lead the way towards the genetic defect in children with a so far unsolved type of the congenital disorders of glycosylation. Raising awareness for less common, non-CDG specific clinical features such as congenital joint contractures, movement disorders or ophthalmological anomalies will encourage clinicians to think of CDG in its more unusual presentation. Clinical grouping also helps to determine the prognosis and provide better counselling for the families.

Risk assessment of acute vascular events in congenital disorder of glycosylation type Ia

The congenital disorder of glycosylation type Ia (CDG-Ia) presents a broad clinical spectrum. Some patients suffer from acute vascular events (thrombosis and bleeding) and stroke-like events. No correlations have been made between the marked hemostasis abnormalities of CDG-Ia and the occurrence of acute vascular events. We report on 6 patients with CDG-Ia presenting vascular events, then we analyze the clinical and hemostasis data of 39 CDG-Ia patients described in the literature, 17 with vascular events (E) and 21 unscathed from any event (EF), to determine the risk factors for acute vascular events in CDG-Ia. Acute vascular events occurred in patients younger than 15 years, especially with fever and prolonged immobilization. Hemostasis and liver cytolysis were statistically abnormal in patients younger than 5 years whatever the occurrence of vascular events and they normalized with time. Higher factors VIII and IX activities were statistically observed in the E cluster (p=0.03) compared to the EF cluster. The activity/antigenicity ratio for protein C (p=0.02) was also higher in the E group. CDG-Ia patients younger than 15 years old are at risk of acute vascular events. The paradoxical results-abnormal VIII and IX factors in EF patients and normal results in E patients, while XI, antithrombin, protein C, ASAT and ALAT are abnormal in both groups, could suggest a disequilibrium between prothrombotic and antithrombotic factors in the E group. Vascular events may also occur in patients where glycoproteins are proportionally more hypoglycosylated, particularly protein C.

Congenital disorder of glycosylation type 1a: Three siblings with a mild neurological phenotype

We report 3 siblings (1 male and 2 female) recently diagnosed with congenital disorder of glycosylation type Ia (CDG-Ia) in their mid-20s. They experience mild mental retardation but manage to function independently in society. Their professions are library assistant, professional artistic painter and secretarial work. All three siblings have cerebellar hypoplasia and ataxia, but are able to ambulate easily. Two of the siblings have required strabismus surgical repairs. All have antithrombin III deficiency, osteoporosis, and mild dysmorphic features. Hypergonadotrophic hypogonadism was a feature of the two female siblings. A type 1 sialotransferrin pattern and phosphomannomutase (PMM) deficiency have been demonstrated. They are compound heterozygotes for R141H and L32R mutations in the PMM2 gene. While there is clinical heterogeneity in CDG-Ia, we believe that our patients are among the mildest of intellectually affected CDG-Ia patients reported to date.

Radiologic and neurophysiologic aspects of stroke-like episodes in children with congenital disorder of glycosylation type Ia

In an effort to shed light on the mechanism of hemiparetic stroke-like events experienced by patients with congenital disorder of glycosylation type Ia, we evaluated 3 children with this disorder by brain imaging studies and continuous electroencephalogram monitoring during such events. No evidence of ischemia or infarction was revealed on imaging studies and electrographic seizures or intermittent epileptiform activity was demonstrated on electrographic recordings. All 3 patients showed clinical and electrographic improvement after administration of antiepileptic medication. Epileptic phenomena can complicate the stroke-like events of patients with congenital disorder of glycosylation type Ia, and the cause of the hemiparesis may indeed be an active epileptic inhibitory process. As such, electroencephalogram monitoring is warranted, and treatment with anticonvulsant agents is indicated.

CDG-Id in two siblings with partially different phenotypes

We present two sibs with congenital disorder of glycosylation (CDG) type Id. Each shows severe global delay, failure to thrive, seizures, microcephaly, axial hypotonia, and disaccharidase deficiency. One sib has more severe digestive issues, while the other is more neurologically impaired. Each is compound heterozygous for a novel point mutation and an already known mutation in the ALG3 gene that leads to the synthesis of a severely truncated oligosaccharide precursor for N-glycans. The defect is corrected by introduction of a normal ALG3 cDNA. CDG should be ruled out in all patients with severe seizures and failure to thrive. (c) 2007 Wiley-Liss, Inc.

Skeletal dysplasia and myelopathy in congenital disorder of glycosylation type IA

We report on a boy with a congenital disorder of glycosylation (CDG) Ia and a severe narrowing of the spinal canal caused by atlantoaxial subluxation with anterior displacement of C1. C1-laminectomy improved the progressive paresis. Progressive paresis caused by spinal cord compression is a hitherto unrecognized complication in patients with CDG-Ia.

Cutaneous findings in congenital disorders of glycosylation: the hanging fat sign

The congenital disorders of glycosylation are a group of rare metabolic disorders with predominantly neurologic findings. Some variants of this disorder also exhibit cutaneous manifestations. We report a patient with a congenital disorder of glycosylation type Ia, the most common form, with emphasis on the cutaneous findings of this type, and summarize the cutaneous findings in the other forms of the disorder.

[The blood oxygen-transport system and oxygen tissue balance in patients with bronchial asthma (BA) concurrent with carbohydrate metabolic disturbances]

Examining the parameters of the blood oxygen-transport system and oxygen tissue balance in 71 patients with bronchial asthma (BA) and in 60 patients with BA concurrent with varying carbohydrate metabolic disturbances (CMDs) revealed differences in oxygen transport. In asthmatic patients without CMDs, the pattern of changes in oxygen balance permitted identification of arteriohypoxemic hypoxia. The high frequency of factors (alkalosis, hypocapnia) that enhance hemoglobin affinity for oxygen, which are compensated for by the increase in 2,3-DPH, as well as hypoxia of peripheral shunting are the specific features of impaired oxygen balance in asthmatic patients with concomitant CMDs that predispose to the development and progression of pulmonary hypertension and cor pulmonale which cause early disability. The determination of the leading link in impaired oxygen transport individualizes treatment approaches and provides evidence for a need for earlier use of metabolic and antihypoxic agents in asthmatic patients with CMDs.

Screening for CDG type Ia in Joubert syndrome

BACKGROUND

The features of Joubert syndrome include hypotonia, ataxia, characteristic neuro-imaging findings, episodic hypoventilation, psychomotor retardation, and abnormal eye movements. Common symptoms in congenital disorders of glycosylation (CDG) type Ia are muscle hypotonia, cerebellar hypoplasia, ataxia, mental retardation, ophthalmologic involvement, failure to thrive, abnormal fat distribution, and hepatopathy. It has been postulated that some Joubert syndrome patients might have an underlying disorder of protein glycosylation.

MATERIAL/METHODS

Screening for disorders of glycosylation was performed in five children diagnosed with Joubert syndrome. Data were retrospectively collected from clinical charts, the patients were reexamined by clinical geneticists, and available neuro-imaging data were also reanalyzed. Diagnoses were established based on results of serum transferrin isoelectric focusing, phosphomannomutase enzyme activity measurements, and DNA mutation analysis.

RESULTS

We confirmed the diagnoses of CDG type Ia in two of the five children originally diagnosed with Joubert syndrome. The symptoms of the two syndromes were clearly distinguishable.

CONCLUSIONS

Syndromic patients with congenital vermis malformations should be screened for congenital disorders of glycosylation.

Gastrointestinal and other clinical manifestations in 17 children with congenital disorders of glycosylation type Ia, Ib, and Ic

OBJECTIVES

The typical signs and symptoms of congenital disorders of glycosylation (CDG) include dysmorphy, failure to thrive, and neurologic abnormalities. However, more and more children diagnosed at a young age are not dysmorphic and do not have neurologic involvement. The authors studied the gastrointestinal and other clinical manifestations of CDG type Ia, Ib, and Ic.

METHODS

As of January 2003, 17 children were identified with CDG at the authors' institution. The medical records of the patients were reviewed.

RESULTS

Five children had CDG Ia, three children CDG Ib, and nine children CDG Ic. Age at diagnosis ranged from 2 months to 15 years. Failure to thrive was present in 80% of patients with CDG Ia, in 66% of those with CDG Ib, and in 11% of those with CDG Ic. Five children had protein-losing enteropathy (two CDG Ia, two CDG Ib, and one CDG Ic). Hepatomegaly was present in 40% of patients with CDG Ia, in 66% of those with CDG Ib, and in 11% of those with CDG Ic. In CDG Ic, hepatomegaly was transient. In CDG Ia, histologic analysis of the liver showed swollen hepatocytes, steatosis, and fibrosis. In CDG Ib, hamartomatous collections of bile ducts were seen. In one patient with CDG Ib, the clinical picture was restricted to congenital hepatic fibrosis for more than a decade.

CONCLUSIONS

The study confirms the heterogeneity of the clinical picture in children with CDG type Ia, Ib, and Ic. Children with protein-losing enteropathy should be tested for CDG. Protein-losing enteropathy can be caused, not only by CDG Ia and Ib, but also by type Ic. Children with congenital hepatic fibrosis should be tested for CDG, even in the absence of other symptoms. In CDG Ib, histologic analysis of the liver showed hamartomatous collections of bile ducts (Meyenburg complex).

[Congenital disorder of type Ia protein glycosylation: clinical, biochemical and molecular characteristics in 2 siblings with cerebellar hypoplasia]

BACKGROUND

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 AND RESULTS

Serum concentrations of the nonglycosylated and hypoglycosylated transferrin were measured 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 beta-glucuronidase in serum were higher and activity of alpha-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.

Cardiac manifestations of carbohydrate-deficient glycoprotein syndrome

A 2-month-old girl with exudative pericarditis and hypertrophic obstructive cardiomyopathy is presented. The child had characteristic dysmorphic features of carbohydrate-deficient glycoprotein syndrome, which was confirmed by serum levels of carbohydrate-deficient transferrin.

[Failure to thrive and intestinal diseases in congenital disorders of glycosylation]

Congenital disorders of glycosylation type I (GDG-I) is a class of genetic multisystem disorders characterised by defective glycosylation of glycoproteins. The characteristics and mechanisms of failure to thrive and intestinal diseases present in CDG-I are anectodal.

PATIENTS AND METHODS

The aim of this study was to analyse 7 CDG-I (4 CDG-Ia, 2 CDG-Ib and 1 CDG-Ix) with important digestive symptoms and failure to thrive in order to characterise the mechanisms implied.

RESULTS

Four children had no skin abnormality or dysmorphia (1 CDG-Ia, 2 CDG-Ib, 1 CDG-Ix). An encephalopathy with cerebellar hypoplasia was present only in the 4 CDG-Ia. Failure to thrive and diarrhea were present during the first month of life in 6 and appeared at 5 years in one CDG-Ia associated to mild or severe hepatopathy in all patients. One CDG-Ia, 1 CDG-Ib, 1 CDG-Ix had an exsudative enteropathy. A positive steatorrhea was present in 3 patients. Five patients had an abnormal small bowel biopsy. Abnormalities were variable: moderate inflammation of the chorion without villous atrophy in 2, intra-enterocyte fat accumulation without villous atrophy in 2, and partial villous atrophy with lymphangectasia in 1. In 2 CDG-Ia the intestinal biopsy was normal. Enteral nutrition in 4 and parenteral nutrition in 2 were effective in 4 patients and 1 patient with an exsudative enteropathy respond to a free fat diet (CDG-Ix).

CONCLUSION

The digestive symptoms with failure to thrive is a common feature of CDG-I and could be the first symptoms. The diagnostic should be suspected if no other cause is found. Mechanisms of the intestinal symptoms appear to be multiple such as inflammation, abnormal enterocyte lipid transport or intestinal permeability related to the abnormal glycosylation of intestinal mucosa glycoproteins.

Spinal deformity associated with carbohydrate-deficient glycoprotein syndrome (Jaeken's syndrome): a report of three cases

STUDY DESIGN

Case reports are presented.

OBJECTIVE

To report the association between carbohydrate-deficient glycoprotein syndrome Type 1a (CDGS Type 1a) and spinal deformity.

SUMMARY OF BACKGROUND DATA

Carbohydrate-deficient glycoprotein syndrome Type 1a is an autosomal recessive metabolic disorder that may occur in association with spinal deformity.

METHODS

Analyses of three cases are presented, including a review of the natural history of the disease.

RESULTS

Three cases were reviewed in which spinal deformities developed in patients with CDGS Type 1a. Two patients required surgical correction of their spinal deformity, and one patient, at this writing, is undergoing conservative treatment. Before surgery, the pediatric hematology service was consulted regarding the patients' CDGD-related hypercoagulability. Of the two patients who underwent surgical correction, one had severe blood loss (7500 mL), and both cases were treated for infection via intravenous antibiotics.

CONCLUSIONS

The incidence of CDGS Type 1a is 1 in 80,0000. Spinal deformity appears to be common in patients with CDGS Type 1a. Therefore, young patients with spinal deformities in combination with mental retardation, failure to thrive, abnormal fat distribution, and other symptoms of CDGS Type 1a should be assessed for this disorder, and patients with CDGS Type 1a should be screened also for spinal deformities. If abnormalities are identified early, treatment outcomes may be optimized.

Neurological presentation in pediatric patients with congenital disorders of glycosylation type Ia

OBJECTIVE

Congenital disorders of glycosylation (CDG), formerly called carbohydrate-deficient glycoprotein syndromes, constitute a newly identified group of multisystem disorders characterized by defective glycosylation of N-glycosylated proteins. The objective of this work was to describe precisely neurological findings in patients with type Ia CDG (CDG-Ia) and to compare our results with the literature.

STUDY DESIGN

We retrospectively reviewed neurological and neurodevelopmental, neuroimaging, and genetic features in ten patients with CDG-Ia who mainly presented with neurological abnormalities during childhood and therefore were referred to a neuropediatrician or a neurogeneticist.

RESULTS

Neurological manifestations had a static clinical course, dominated by mental retardation and cerebellar dysfunction, and acute episodes: stroke-like episodes and seizures. However, microcephaly, retinopathy, and polyneuropathy were progressive. All patients had severe global neurodevelopmental delay: only one was able to walk alone at ten years of age and only one could read. Marked heterogeneity in manifestations and delay of diagnosis was noted across the patients. Cerebellar hypoplasia was found by magnetic resonance imaging in all ten patients and olivopontocerebellar hypoplasia in four patients. As in the literature, there was no clear phenotype-mutation correlation.

CONCLUSION

Our findings confirm the importance of a precise and complete description of the neurological and neuroradiological phenotype delineating the phenotype of CDG-Ia to increase the likelihood of diagnosing the disease.

Congenital disorder of glycosylation Ib (CDG-Ib) without gastrointestinal symptoms

We report a 7-year-old girl with hyperinsulinaemic hypoglycaemia and hepatomegaly due to congenital disorder of glycosylation (CDG) Ib without gastrointestinal symptoms. Oral mannose therapy produced clinical and biochemical normalization after 2 years of treatment.

Severe transient myocardial ischaemia caused by hypertrophic cardiomyopathy in a patient with congenital disorder of glycosylation type Ia

Severely affected children with congenital disorder of glycosylation type Ia (CDG-Ia; MIM 212065) may develop hypertrophic cardiomyopathy. In this report we describe the near-death of a 10-month-old girl with CDG-Ia due to acute left-ventricular outlet obstruction caused by hypertrophic cardiomyopathy and acute dehydration. The girl had multi-organ failure and signs of severe myocardial damage mimicking myocardial infarction.

CONCLUSION

hypertrophic cardiomyopathy contributes to the high mortality of young children with congenital disorder of glycosylation type Ia. Even if cardiomyopathy in this disease is non-obstructive, acute fluid-loss might cause left ventricular outflow tract obstruction and life-threatening myocardial ischaemia. Patients with congenital disorder of glycosylation type Ia are at risk for cardiac complications and should be monitored regularly by echocardiography.

Prepubertal growth in congenital disorder of glycosylation type Ia (CDG-Ia)

AIMS

To delineate the pattern of growth in prepubertal children with congenital disorder of glycosylation type Ia (CDG-Ia) in order to identify critical period(s) and possible cause(s) of growth failure.

METHODS

Longitudinal measurements of weight, length/height, and head circumference from birth to 10 years of age in 25 CDG-Ia patients with the R141H/F119L PMM2 genotype were analysed. The data and derived body mass indices (BMI) were compared with standards and expressed as standard deviation scores (SDS). A linear mixed effects model was fitted to each set of data, and mean curves were estimated.

RESULTS

The mean weight SDS decreased from -0.3 at birth to -3.0 at 7 months of age and remained low or increased slightly. The mean length SDS decreased from zero at birth to -2.4 at 7 months of age followed by a slight increase to a maximum of -1.8 SDS at the end of the second year of life. After age 2 the mean length/height SDS decreased again. The mean BMI SDS at birth was -0.7 and declined to a minimum of -2.8 at the end of the second year of life followed by a gradual increase. The mean head circumference SDS declined gradually from 0 at 3 months of age to -1.9 at age 5.

CONCLUSION

CDG-Ia patients with the R141H/F119L genotype have normal fetal growth and an immediate postnatal onset of severe growth failure. A notable decline in weight end length SDS takes place during the first seven months of life with no prepubertal catch up.