ALG1-CDG | |
---|---|
Other names | CDG-IK |
Specialty | Medical genetics |
Usual onset | birth |
Causes | biallelic pathogenic variants in ALG1 |
Treatment | none |
ALG1-CDG is an autosomal recessive congenital disorder of glycosylation caused by biallelic pathogenic variants in ALG1 . The first cases of ALG1-CDG were described in 2004, and the causative gene was identified at the same time. This disorder was originally designated CDG-IK, under earlier nomenclature for congenital disorders of glycosylation. [1] Clinically, individuals with ALG1-CDG have developmental delay, hypotonia, seizures and microcephaly. [2] Fewer than 60 cases of ALG1-CDG have been confirmed in published literature. [3] ALG1-CDG can be suspected based on clinical findings, and abnormal serum transferrin glycosylation test results. [3] Confirmation of the diagnosis can be performed based on sequence analysis of ALG1. The analysis of ALG1 is complicated by the presence of a pseudogene. [4] There are no specific treatments for ALG1-CDG, and most care consists of managing symptoms. [1] [3]
A congenital disorder of glycosylation is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defective. Congenital disorders of glycosylation are sometimes known as CDG syndromes. They often cause serious, sometimes fatal, malfunction of several different organ systems in affected infants. The most common sub-type is PMM2-CDG where the genetic defect leads to the loss of phosphomannomutase 2 (PMM2), the enzyme responsible for the conversion of mannose-6-phosphate into mannose-1-phosphate.
Microcephaly is a medical condition involving a smaller-than-normal head. Microcephaly may be present at birth or it may develop in the first few years of life. Brain development is often affected; people with this disorder often have an intellectual disability, poor motor function, poor speech, abnormal facial features, seizures and dwarfism.
Congenital muscular dystrophies are autosomal recessively-inherited muscle diseases. They are a group of heterogeneous disorders characterized by muscle weakness which is present at birth and the different changes on muscle biopsy that ranges from myopathic to overtly dystrophic due to the age at which the biopsy takes place.
Phosphomannomutase 2 is an enzyme that in humans is encoded by the PMM2 gene.
Dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase is an enzyme that in humans is encoded by the ALG6 gene.
Alpha-1,3/1,6-mannosyltransferase ALG2 is an enzyme that is encoded by the ALG2 gene. Mutations in the human gene are associated with congenital defects in glycosylation The protein encoded by the ALG2 gene belongs to two classes of enzymes: GDP-Man:Man1GlcNAc2-PP-dolichol alpha-1,3-mannosyltransferase and GDP-Man:Man2GlcNAc2-PP-dolichol alpha-1,6-mannosyltransferase.
Probable dolichyl pyrophosphate Glc1Man9GlcNAc2 alpha-1,3-glucosyltransferase is an enzyme that in humans is encoded by the ALG8 gene.
Dolichol-phosphate mannosyltransferase is an enzyme that in humans is encoded by the DPM1 gene.
Dolichyl-P-Man:Man(7)GlcNAc(2)-PP-dolichyl-alpha-1,6-mannosyltransferase is an enzyme that in humans is encoded by the ALG12 gene.
Dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase is an enzyme that, in humans, is encoded by the ALG3 gene.
GDP-fucose transporter 1 is a protein that in humans is encoded by the SLC35C1 gene.
Chitobiosyldiphosphodolichol beta-mannosyltransferase is an enzyme that is encoded by ALG1 whose structure and function has been conserved from lower to higher organisms.
Congenital dyserythropoietic anemia (CDA) is a rare blood disorder, similar to the thalassemias. CDA is one of many types of anemia, characterized by ineffective erythropoiesis, and resulting from a decrease in the number of red blood cells (RBCs) in the body and a less than normal quantity of hemoglobin in the blood. CDA may be transmitted by both parents autosomal recessively or dominantly.
Steroid 5-alpha-reductase 3, also known as 3-oxo-5-alpha-steroid 4-dehydrogenase 3, is an enzyme that in humans is encoded by the SRD5A3 gene. It is one of three forms of 5α-reductase.
Congenital dyserythropoietic anemia type II, or hereditary erythroblastic multinuclearity with positive acidified serum lysis test (HEMPAS) is a rare genetic anemia in humans characterized by hereditary erythroblastic multinuclearity with positive acidified serum lysis test.
PGM3 deficiency is a rare genetic disorder of the immune system associated with diminished phosphoglucomutase 3 function. PGM3 is an enzyme which in humans is encoded by gene PGM3. This disorder manifests as severe atopy, immune deficiency, autoimmunity, intellectual disability, and hypomyelination. In 2014, Investigators Atfa Sassi at the Pasteur Institute of Tunis, Sandra Lazaroski at the University Medical Center Freiburg, and Gang Wu at the Imperial College London, identified PGM3 mutations in nine patients from four consanguineous families. In the same year, a researchers from the laboratories of Joshua Milner and Helen Su at the National Institute of Allergy and Infectious Disease at the U.S. National Institutes of Health described PGM3 deficiency in eight additional patients from two families.
PMM2 deficiency or PMM2-CDG, previously CDG-Ia, is a very rare genetic disorder caused by mutations in PMM2. It is an autosomal recessive disease that is the most common type of congenital disorder of glycosylation or CDG. PMM2-CDG is the most common of a growing family of more than 130 extremely rare inherited metabolic disorders. Only about 800 children and adults have been reported worldwide.
MPI-CDG is an autosomal recessive congenital disorder of glycosylation caused by biallelic pathogenic variants in MPI. The clinical symptoms in MPI-CDG are caused by deficient activity of the enzyme mannose phosphate isomerase. Clinically, the most common symptoms of MPI-CDG are chronic diarrhea, failure to thrive, protein-losing enteropathy, and coagulopathy. MPI-CDG differs from most other described glycosylation disorders due to its lack of central nervous system involvement, and because it has treatment options besides supportive care. Treatment with oral mannose has been shown to improve most symptoms of the disease. If left untreated, MPI-CDG can be fatal. MPI-CDG was previously known as CDG-IB. The disorder was first described clinically in 1986, and the underlying genetic defect was identified in 1998.
SRD5A3-CDG is a rare, non X-linked congenital disorder of glycosylation (CDG) due to a mutation in the steroid 5 alpha reductase type 3 gene. It is one of over 150 documented types of Congenital disorders of Glycosylation. Like many other CDGs, SRD5A3 is ultra-rare, with around 38 documented cases in the world.
SLC35A1-CDG is a rare inherited disorder that mainly affects the vascular systems of the body. It forms part of a large group of disorders called congenital disorders of glycosylation. It is caused by mutations in the SLC35A1 gene, located in the sixth chromosome.