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Role of Tandem Mass Spectrometry in Diagnosis and Management of Inborn Errors of Metabolism
Published in P. Mereena Luke, K. R. Dhanya, Didier Rouxel, Nandakumar Kalarikkal, Sabu Thomas, Advanced Studies in Experimental and Clinical Medicine, 2021
Kannan Vaidyanathan, Sandhya Gopalakrishnan
Proteomic study on patients with congenital disorder of glycosylation type 1a (CDG1a) revealed 14 proteins which are expressed in patients and not seen in controls. The most notable proteins are those involved in immune response, coagulation mechanism, and tissue protection against oxidative stress and include alpha(2)-macroglobulin, afamin, fibrin, and fibrinogen [68]. An LC-MS/MS method was developed for the simultaneous measurement of delta aminolevulinic acid and porphobilinogen in patients with acute porphyria [69]. Thirty differentially expressed proteins were identified in Hutchinson-Gilford progeria syndrome (HGPS); these genes were involved in methylation, ionic calcium-binding, cytoskeleton, duplication, and regulation of apoptosis. These genes may therefore be involved in the aging process [70].
Metabolic disorders
Published in Rachel U Sidwell, Mike A Thomson, Concise Paediatrics, 2020
Rachel U Sidwell, Mike A Thomson
Congenital disorders of glycosylation (CDG disorders, alternatively carbohydrate deficient glycoprotein disorders). Prior to a protein being exported from a cell carbohydrate moieties are attached by the endoplasmic reticulum and golgi apparatus in a process known as glycosylation. This requires a huge variety of enzymes and defects in any one of these lead to a CDG disorder. Preliminary diagnosis is made by studying the glycosylation pattern of transferrin (a glycoprotein)
The gastrointestinal tract
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
In addition to the cystic diseases of the liver and/or kidneys, congenital hepatic fibrosis can also arise in association with Leber congenital amaurosis and juvenile nephronophthisis (the heterogeneous Senior-Løken syndrome), or as part of a spectrum of ciliopathies (cerebellar vermis aplasia, oligophrenia, congenital ataxia, coloboma and hepatic fibrosis [COACH] syndrome, with features overlapping with Joubert syndrome and Meckel syndrome). It is also a feature of congenital disorder of glycosylation (CDG) type 1B.
Ocular abnormalities in a patient with congenital disorder of glycosylation type Ig
Published in Ophthalmic Genetics, 2019
Hamed Esfandiari, Marilyn B. Mets, Katherine H. Kim, Sudhi P. Kurup
Congenital disorders of glycosylation (CDG) are a genetically and clinically heterogeneous group of over a hundred diseases that are characterized by a deficiency of one of the many steps in glycan synthesis or modification pathways (1). In CDG type I there is a defect in the assembly of lipid-linked oligosaccharides or their transfer onto nascent glycoproteins. Most subtypes are extremely rare; CDG type Ia is the most common and best described subtype of CDG I and presents with developmental delay, failure to thrive, characteristic dysmorphic features, and neurological findings. Ocular abnormalities are reported in 70% of patients with CDG type Ia (5,6). Convergent strabismus is the characteristic ophthalmic finding, and retinitis pigmentosa is the most common retinal abnormality (3). Ocular abnormalities have been reported in other CDG I subtypes, including optic atrophy, cataract, retinitis pigmentosa, strabismus, nystagmus, iris coloboma, and chorioretinal coloboma (7–10).
Early-onset retinal dystrophy and chronic dermatitis in a girl with an undiagnosed congenital disorder of glycosylation (SRD5A3-CDG)
Published in Ophthalmic Genetics, 2018
Congenital disorders of glycosylation (CDG syndromes) are a family of multisystem disorders due to abnormal protein and lipid glycosylation (1). Over 100 types have been described to date from variants in different genes. Clinical features and severity vary and can include ocular involvement, but the most recurrent finding is neurological impairment. Biallelic variants in the gene steroid 5α-reductase type 3 (SRD5A3), responsible for the conversion of polyprenol to dolichol, cause SRD5A3-CDG, formally known as Type Iq (2,3). Variants in the gene result in impaired protein N-glycosylation, C-mannosylation, mannose-linked glycan synthesis, and glycophospholipid anchor synthesis. SRD5A3-CDG was first described in two unrelated Baluchi families with iris and chorioretinal colobomas, optic atrophy, atopic dermatitis, cerebellar hypoplasia, and developmental disability (2). Both families harbored the same homozygous SRD5A3 deletion (p.Gln96delinsX) (3). The purpose of this report is to highlight the presentation of a Baluchi girl with early-onset retinal dystrophy, chronic dermatitis, and developmental disability who was found to have undiagnosed SRD5A3-CDG. She was homozygous for the SRD5A3 deletion p.Gln96delinsX but did not have ocular coloboma, which demonstrates that ocular coloboma is not an essential finding in children homozygous for this specific deletion.