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ALG1-congenital disorder of glycosylation(CDGIk; CDG1K)

MedGen UID:
419308
Concept ID:
C2931005
Disease or Syndrome
Synonyms: ALG1-CDG; ALG1-CDG (CDG-Ik); CDG 1K; CDG Ik; Congenital disorder of glycosylation type 1K; CONGENITAL DISORDER OF GLYCOSYLATION, TYPE Ik
SNOMED CT: Asparagine-linked glycosylation 1 congenital disorder of glycosylation (720941007); ALG1 congenital disorder of glycosylation (720941007); Congenital disorder of glycosylation type 1K (720941007); Carbohydrate deficient glycoprotein syndrome type Ik (720941007); Mannosyltransferase 1 deficiency (720941007); ALG1-CDG - asparagine-linked glycosylation 1 congenital disorder of glycosylation (720941007)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): ALG1 (16p13.3)
 
Monarch Initiative: MONDO:0012052
OMIM®: 608540
Orphanet: ORPHA79327

Definition

Congenital disorders of glycosylation (CDGs) comprise a group of multisystem diseases with mostly severe psychomotor and mental retardation. Type I CDG comprises those disorders in which there are defects that affect biosynthesis of dolichol-linked oligosaccharides in the cytosol or the endoplasmic reticulum (ER), as well as defects involving the transfer of oligosaccharides onto nascent glycoproteins. Type II CDG comprises all defects of further trimming and elongation of N-linked oligosaccharides in the ER and Golgi (Schwarz et al., 2004). CDG1K is a type I CDG characterized by predominant neurologic involvement. Survival ranges from the second day of life to adulthood. The liver is affected in a minority of patients and shows hepatomegaly, edema, ascites, cholestatic jaundice, portal hypertension, and Budd-Chiari syndrome (summary by Marques-da-Silva et al., 2017). For a general discussion of CDGs, see CDG1A (212065). [from OMIM]

Additional description

From MedlinePlus Genetics
ALG1-congenital disorder of glycosylation (ALG1-CDG, also known as congenital disorder of glycosylation type Ik) is an inherited disorder with varying signs and symptoms that typically develop during infancy and can affect several body systems.

Individuals with ALG1-CDG often have intellectual disability, delayed development, and weak muscle tone (hypotonia). Many affected individuals develop seizures that can be difficult to treat. Individuals with ALG1-CDG may also have movement problems such as involuntary rhythmic shaking (tremor) or difficulties with movement and balance (ataxia).

People with ALG1-CDG often have problems with blood clotting, which can lead to abnormal clotting or bleeding episodes. Additionally, affected individuals may produce abnormally low levels of proteins called antibodies (or immunoglobulins), particularly immunoglobulin G (IgG). Antibodies help protect the body against infection by foreign particles and germs. A reduction in antibodies can make it difficult for affected individuals to fight infections.

Some people with ALG1-CDG have physical abnormalities such as a small head size (microcephaly); unusual facial features; joint deformities called contractures; long, slender fingers and toes (arachnodactyly); or unusually fleshy pads at the tips of the fingers and toes. Eye problems that may occur in people with this condition include eyes that do not point in the same direction (strabismus) or involuntary eye movements (nystagmus). Rarely, affected individuals develop vision loss.

Less common abnormalities that occur in people with ALG1-CDG include respiratory problems, reduced sensation in their arms and legs (peripheral neuropathy), swelling (edema), and gastrointestinal difficulties.

The signs and symptoms of ALG1-CDG are often severe, with affected individuals surviving only into infancy or childhood. However, some people with this condition are more mildly affected and survive into adulthood.  https://medlineplus.gov/genetics/condition/alg1-congenital-disorder-of-glycosylation

Clinical features

From HPO
Cardiomyopathy
MedGen UID:
209232
Concept ID:
C0878544
Disease or Syndrome
A myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valvular disease and congenital heart disease sufficient to cause the observed myocardial abnormality.
Fetal growth restriction
MedGen UID:
4693
Concept ID:
C0015934
Pathologic Function
An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.
Hepatomegaly
MedGen UID:
42428
Concept ID:
C0019209
Finding
Abnormally increased size of the liver.
Seizure
MedGen UID:
20693
Concept ID:
C0036572
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
Cerebral atrophy
MedGen UID:
116012
Concept ID:
C0235946
Disease or Syndrome
Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Multifocal epileptiform discharges
MedGen UID:
866864
Concept ID:
C4021219
Finding
An abnormality in cerebral electrical activity recorded along the scalp by electroencephalography (EEG) and being identified at multiple locations (foci).
Joint contracture
MedGen UID:
3228
Concept ID:
C0009918
Anatomical Abnormality
A limitation in the passive range of motion of a joint resulting from loss of elasticity in the periarticular tissues owing to structural changes of non-bony tissues, such as muscles, tendons, ligaments, joint capsules or skin. A contracture prevents movement of the associated body part.
Micrognathia
MedGen UID:
44428
Concept ID:
C0025990
Congenital Abnormality
Developmental hypoplasia of the mandible.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Flexion contracture
MedGen UID:
83069
Concept ID:
C0333068
Anatomical Abnormality
A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.
Large fontanelles
MedGen UID:
105329
Concept ID:
C0456132
Finding
In newborns, the two frontal bones, two parietal bones, and one occipital bone are joined by fibrous sutures, which form a small posterior fontanelle, and a larger, diamond-shaped anterior fontanelle. These regions allow for the skull to pass the birth canal and for later growth. The fontanelles gradually ossify, whereby the posterior fontanelle usually closes by eight weeks and the anterior fontanelle by the 9th to 16th month of age. Large fontanelles are diagnosed if the fontanelles are larger than age-dependent norms.
Generalized hypotonia
MedGen UID:
346841
Concept ID:
C1858120
Finding
Generalized muscular hypotonia (abnormally low muscle tone).
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Splenomegaly
MedGen UID:
52469
Concept ID:
C0038002
Finding
Abnormal increased size of the spleen.
Type I transferrin isoform profile
MedGen UID:
324900
Concept ID:
C1837899
Finding
Abnormal transferrin isoform profile consistent with a type I congenital disorder of glycosylation. In the traditional nomenclature for congenital disorders of glycosylation, absence of entire glycans was designated type I, and loss of one or more monosaccharides as type II.
Thin vermilion border
MedGen UID:
108294
Concept ID:
C0578038
Finding
Height of the vermilion of the medial part of the lip more than 2 SD below the mean, or apparently reduced height of the vermilion of the lip in the frontal view. The vermilion is the red part of the lips (and confusingly, the vermilion itself is also often referred to as being equivalent the lips).
Abnormality of the amniotic fluid
MedGen UID:
488828
Concept ID:
C0266781
Finding
Abnormality of the amniotic fluid, which is the fluid contained in the amniotic sac surrounding the developing fetus.
Non-immune hydrops fetalis
MedGen UID:
105327
Concept ID:
C0455988
Disease or Syndrome
Hydrops fetalis is a descriptive term for generalized edema of the fetus, with fluid accumulation in extravascular components and body cavities. It is not a diagnosis in itself, but a symptom and end-stage result of a wide variety of disorders. In the case of immune hydrops fetalis, a frequent cause is maternofetal incompatibility as in that related to a number of genetic anemias and metabolic disorders expressed in the fetus; in other instances, it remains idiopathic and likely multifactorial (summary by Bellini et al., 2009). Nonimmune hydrops fetalis accounts for 76 to 87% of all described cases of hydrops fetalis (Bellini et al., 2009). Genetic Heterogeneity of Hydrops Fetalis In southeast Asia, alpha-thalassemia (604131) is the most common cause of hydrops fetalis, accounting for 60 to 90% of cases. Almost all of these cases result from homozygous deletion of the HBA1 (141800) and HBA2 (141850) genes. A few cases have been reported that had 1 apparently normal alpha-globin gene, termed the hemoglobin H (613978) hydrops fetalis syndrome (summary by Chui and Waye, 1998). Other genetic disorders predisposing to NIHF include other congenital anemias, such as erythropoietic porphyria (e.g., 606938.0013), and many metabolic disorders, such as one form of Gaucher disease (e.g., 606463.0009), infantile sialic acid storage disease (269920), mucopolysaccharidosis type VII (253220), glycogen storage disease IV (232500), congenital disorder of glycosylation type Ia (212065), and disorders of lymphatic malformation (see, e.g., LMPHM1, 153100).
Hypogonadism
MedGen UID:
5711
Concept ID:
C0020619
Disease or Syndrome
A decreased functionality of the gonad.
Hypertelorism
MedGen UID:
9373
Concept ID:
C0020534
Finding
Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
Follow this link to review classifications for ALG1-congenital disorder of glycosylation in Orphanet.

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