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March 2023

March 1, 2023

Successful heart transplantation in an infant with phosphoglucomutase 1 deficiency (PGM1-CDG)

Altassan R, Albert-Brotons DC, Alowain M, Al-Halees Z, Jaeken J, Morava E. JIMD Rep., March 1, 2023

We report successful heart transplantation in a phosphoglucomutase 1 deficient (PGM1-CDG) patient. She presented with facial dysmorphism, bifid uvula and structural heart defects. Newborn screening was positive for classic galactosemia. The patient was on a galactose-free diet for 8 months. Eventually, whole exome sequencing excluded the galactosemia and revealed PGM1-CDG. Oral D-galactose therapy was started. Rapid deterioration of the progressive dilated cardiomyopathy prompted heart transplantation at the age of 12 months. Cardiac function was stable in the first 18 months of follow-up, and hematologic, hepatic, and endocrine laboratory findings improved during D-galactose therapy. The latter therapy improves several systemic symptoms and biochemical abnormalities in PGM1-CDG but does not correct the heart failure related to cardiomyopathy. Heart transplantation has so far only been described in DOLK-CDG.


February 2023

February 28, 2023

ALG11-CDG: novel variant and review of the literature

Erdal AE, Ceylan AC, Gücüyener K, Öktem RM, Kıreker Köylü O, Kasapkara ÇS. J Pediatr Endocrinol Metab., February 28, 2023

Asparagine-dependent glycosylation 11-congenital disorders of glycosylation (ALG11-CDG) is a rare autosomal recessive N-glycosylation defect with multisystem involvement particularly neurological symptoms such as epilepsy and neuromotor developmental delay. A 31-month-old male patient admitted to our center with complaints of axial hypotonia, drug-resistant myoclonic seizures, microcephaly and deafness. [...]Compound heterozygous mutations of the ALG11 gene were found by whole exome sequencing (WES) analysis. It was determined that the c.476T>C mutati


February 26, 2023

The role of PGM1-isoform 2 in PGM1-CDG: one step closer to genotype-phenotype correlation?

Radenkovic S, Laerdahl JK, Backe PH, Morava E. J Inherit Metab Dis., February 26, 2023


February 16, 2023

N-Glycoprofiling of SLC35A2-CDG: Patient with a Novel Hemizygous Variant

Kodríková R et al. Biomedicines, February 16, 2023

Congenital disorders of glycosylation (CDG) are a group of rare inherited metabolic disorders caused by a defect in the process of protein glycosylation. In this work, we present a comprehensive glycoprofile analysis of a male patient with a novel missense variant in the SLC35A2 gene, coding a galactose transporter that translocates UDP-galactose from the cytosol to the lumen of the endoplasmic reticulum and Golgi apparatus. Isoelectric focusing of serum transferrin, which resulted in a CDG type II pattern, was followed by structural analysis of transferrin and serum N-glycans, as well as the analysis of apolipoprotein CIII O-glycans by mass spectrometry.


February 16, 2023

Generation and characterization of NGLY1 patient-derived midbrain organoids

Abbott J, et al. Front Cell Dev Biol., February 16, 2023

NGLY1 deficiency is an ultra-rare, autosomal recessive genetic disease caused by mutations in the NGLY1 gene encoding N-glycanase one that removes N-linked glycan. Patients with pathogenic mutations in NGLY1 have complex clinical symptoms including global developmental delay, motor disorder and liver dysfunction. To better understand the disease pathogenesis and the neurological symptoms of the NGLY1 deficiency we generated and characterized midbrain organoids using patient-derived iPSCs from two patients with distinct disease-causing mutations-one homozygous for p. Q208X, the other compound heterozygous for p. L318P and p. R390P and CRISPR generated NGLY1 knockout iPSCs.


February 11, 2023

Phosphomannomutase 2 (PMM2) variants leading to hyperinsulinism-polycystic kidney disease are associated with early-onset inflammatory bowel disease and gastric antral foveolar hyperplasia

Kiparissi F, et al. Hum Genet., February 11, 2023

Phosphomannomutase 2 (PMM2) deficiency causes Congenital Disorder of Glycosylation (PMM2-CDG), but does not have a recognised association with Inflammatory Bowel Disease (IBD). A distinct clinical syndrome of hyperinsulinism and autosomal recessive polycystic kidney disease (HIPKD) arises in the context of a specific variant in the PMM2 promotor, either in homozygosity, or compound heterozygous with a deleterious PMM2 variant. Here, we describe the development of IBD in three patients with PMM2-HIPKD, with onset of IBD at 0, 6, and 10 years of age.


February 8, 2023

Analysis of urinary oligosaccharide excretion patterns by UHPLC/HRAM mass spectrometry for screening of lysosomal storage disorders

Hagemeijer MC, et al. J Inherit Metab Dis., February 8, 2023

Oligosaccharidoses, sphingolipidoses and mucolipidoses are lysosomal storage disorders (LSDs) in which defective breakdown of glycan-side chains of glycosylated proteins and glycolipids leads to the accumulation of incompletely degraded oligosaccharides within lysosomes. In metabolic laboratories, these disorders are commonly diagnosed by thin-layer chromatography (TLC) but more recently also mass spectrometry-based approaches have been published. To expand the possibilities to screen for these diseases, we developed an ultra-high-performance liquid chromatography (UHPLC) with high-resolution accurate mass (HRAM) mass spectrometry (MS) screening platform, together with an open-source iterative bioinformatics pipeline.[...] Using this platform, we were able to identify α-mannosidosis, β-mannosidosis, α-N-acetylgalactosaminidase deficiency, sialidosis, galactosialidosis, fucosidosis, aspartylglucosaminuria, GM1 gangliosidosis, GM2 gangliosidosis (M. Sandhoff) and mucolipidosis II/III in patient samples. Aberrant urinary oligosaccharide excretions were also detected for other disorders, including NGLY1 congenital disorder of deglycosylation, sialic acid storage disease, MPS type IV B and GSD II (Pompe disease).


February 8, 2023

Severe Ciliopathy-Like Phenotype in an Infant With a Novel MPDU1 Missense Variant

Darouich S, Bellamine H, Khamassi I. Pediatr Dev Pathol., February 8, 2023

Congenital disorders of glycosylation (CDG) are associated with ciliary dysfunction due to altered glycosylation of ciliary glycoproteins. We describe a severe ciliopathy-like phenotype in a female infant associated with a novel homozygous missense variant NM_004870.4(MPDU1):c.503G>A/p.Gly168Glu. Our findings, based on the co-segregation of the variant with the phenotype and in-silico analysis, implicate this MPDU1 missense variant in this disorder. Matched phenotype includes symmetric growth restriction, facial dysmorphism, ichthyosis, hepatomegaly with severe duct plate malformation, renal cortical tubular and glomerular cysts, moderate cerebral tetraventricular dilatation, and severe pontocerebellar hypoplasia. According to this observation, CDG should be included in the workup of infantile ciliopathy-like disorder.


February 2, 2023

A Case of ALG6-CDG with Explosive Onset of Intractable Epilepsy During Infancy

Clark DJ, Murray T, Drees M, Kulkarni N. Child Neurol., February 2, 2023

ALG6-CDG is a rare, but second most common, type 1 congenital disorder of glycosylation (CDG) caused by a defect in the α-1-3-glucosyltransferase (ALG6) enzyme in the N-glycan assembly pathway. Many mutations have been identified and inherited in an autosomal recessive pattern. There are less than 100 ALG6-CDG cases reported, all sharing the phenotype of hypotonia and developmental delay. The majority (perhaps >70%) have seizures, but a minority have intractable epilepsy or epileptic encephalopathy. We report the clinical course, EEG findings, and neuroimaging of a child found to have compound heterozygous alleles c.257 + 5G > A and c.680G > A (p.G227E) who developed explosive onset of intractable epilepsy and epileptic encephalopathy. Initially, CDG was not suspected due to its rarity and lack of multi-organ system involvement, but rapid whole exam sequence (8-day turnaround) revealed the specific diagnosis quickly.


January 2023

January 31, 2023

Elevated Oxysterol and N-Palmitoyl-O-Phosphocholineserine Levels in Congenital Disorders of Glycosylation

Dang Do AN, et al. J Inherit Metab Dis., January 31, 2023

Congenital disorders of glycosylation (CDG) and Niemann-Pick type C (NPC) disease are inborn errors of metabolism that can both present with infantile-onset severe liver disease and other multi-systemic manifestations. Plasma bile acid and N-palmitoyl-O-phosphocholineserine (PPCS) are screening biomarkers with proposed improved sensitivity and specificity for NPC. We report an infant with ATP6AP1-CDG who presented with cholestatic liver failure and elevated plasma oxysterols and bile acid, mimicking NPC clinically and biochemically. On further investigation, PPCS, but not the bile acid derivative N-(3β,5α,6β-trihydroxy-cholan-24-oyl) glycine (TCG), were elevated in plasma samples from individuals with ATP6AP1-, ALG1-, ALG8-, and PMM2-CDG. These findings highlight the importance of keeping CDG within the diagnostic differential when evaluating children with early onset severe liver disease and elevated bile acid or PPCS to prevent delayed diagnosis and treatment.