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ALG12-congenital disorder of glycosylation(CDG1G)

MedGen UID:
443954
Concept ID:
C2931001
Disease or Syndrome
Synonyms: ALG12-CDG; CDG 1G; CDG Ig; CDG1G; Congenital disorder of glycosylation, type Ig
SNOMED CT: ALG12-congenital disorder of glycosylation (711155008); Congenital disorder of glycosylation type Ig (711155008); Congenital disorder of glycosylation type 1G (711155008)
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): ALG12 (22q13.33)
 
Monarch Initiative: MONDO:0011783
OMIM®: 607143
Orphanet: ORPHA79324

Definition

Congenital disorders of glycosylation (CDG), previously called carbohydrate-deficient glycoprotein syndromes (CDGSs), are a group of hereditary multisystem disorders first recognized by Jaeken et al. (1980). The characteristic biochemical abnormality of CDGs is the hypoglycosylation of glycoproteins, which is routinely determined by isoelectric focusing (IEF) of serum transferrin. Type I CDG comprises those disorders in which there is a defect in the assembly of lipid-linked oligosaccharides or their transfer onto nascent glycoproteins, whereas type II CDG comprises defects of trimming, elongation, and processing of protein-bound glycans. CDG1G is a multisystem disorder characterized by impaired psychomotor development, dysmorphic features, failure to thrive, male genital hypoplasia, coagulation abnormalities, and immune deficiency. More variable features include skeletal dysplasia, cardiac anomalies, ocular abnormalities, and sensorineural hearing loss. Some patients die in the early neonatal or infantile period, whereas others are mildly affected and live to adulthood (summary by Tahata et al., 2019). For a general discussion of CDGs, see CDG1A (212065). [from OMIM]

Additional description

From MedlinePlus Genetics
ALG12-congenital disorder of glycosylation (ALG12-CDG, also known as congenital disorder of glycosylation type Ig) is an inherited disorder with varying signs and symptoms that can affect several body systems. Individuals with ALG12-CDG typically develop signs and symptoms of the condition during infancy. They may have problems feeding and difficulty growing and gaining weight at the expected rate (failure to thrive). In addition, affected individuals often have intellectual disability, delayed development, and weak muscle tone (hypotonia), and some develop seizures.

Some people with ALG12-CDG have physical abnormalities such as a small head size (microcephaly) and unusual facial features. These features can include folds of skin that cover the inner corners of the eyes (epicanthal folds), a prominent nasal bridge, and abnormally shaped ears. Some males with ALG12-CDG have abnormal genitalia, such as a small penis (micropenis) and undescended testes.

People with ALG12-CDG often produce abnormally low levels of proteins called antibodies (or immunoglobulins), particularly immunoglobulin G (IgG). Antibodies help protect the body against infection by attaching to specific foreign particles and germs, marking them for destruction. A reduction in antibodies can make it difficult for affected individuals to fight infections.

Less common abnormalities seen in people with ALG12-CDG include a weakened heart muscle (cardiomyopathy) and poor bone development, which can lead to skeletal abnormalities.  https://medlineplus.gov/genetics/condition/alg12-congenital-disorder-of-glycosylation

Clinical features

From HPO
Cryptorchidism
MedGen UID:
8192
Concept ID:
C0010417
Congenital Abnormality
Cryptorchidism, or failure of testicular descent, is a common human congenital abnormality with a multifactorial etiology that likely reflects the involvement of endocrine, environmental, and hereditary factors. Cryptorchidism can result in infertility and increases risk for testicular tumors. Testicular descent from abdomen to scrotum occurs in 2 distinct phases: the transabdominal phase and the inguinoscrotal phase (summary by Gorlov et al., 2002).
Small scrotum
MedGen UID:
141577
Concept ID:
C0455792
Finding
Apparently small scrotum for age.
Hypospadias
MedGen UID:
163083
Concept ID:
C0848558
Congenital Abnormality
Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum.
Micropenis
MedGen UID:
1633603
Concept ID:
C4551492
Congenital Abnormality
Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.
Clubfoot
MedGen UID:
3130
Concept ID:
C0009081
Congenital Abnormality
Clubfoot is a congenital limb deformity defined as fixation of the foot in cavus, adductus, varus, and equinus (i.e., inclined inwards, axially rotated outwards, and pointing downwards) with concomitant soft tissue abnormalities (Cardy et al., 2007). Clubfoot may occur in isolation or as part of a syndrome (e.g., diastrophic dysplasia, 222600). Clubfoot has been reported with deficiency of long bones and mirror-image polydactyly (Gurnett et al., 2008; Klopocki et al., 2012).
Short femur
MedGen UID:
87499
Concept ID:
C0345375
Congenital Abnormality
An abnormal shortening of the femur.
Hypoplasia of the radius
MedGen UID:
672334
Concept ID:
C0685381
Congenital Abnormality
Underdevelopment of the radius.
Short humerus
MedGen UID:
316907
Concept ID:
C1832117
Congenital Abnormality
Underdevelopment of the humerus.
Sandal gap
MedGen UID:
374376
Concept ID:
C1840069
Finding
A widely spaced gap between the first toe (the great toe) and the second toe.
Short tibia
MedGen UID:
338005
Concept ID:
C1850259
Finding
Underdevelopment (reduced size) of the tibia.
Rhizomelia
MedGen UID:
357122
Concept ID:
C1866730
Congenital Abnormality
Disproportionate shortening of the proximal segment of limbs (i.e. the femur and humerus).
Patent ductus arteriosus
MedGen UID:
4415
Concept ID:
C0013274
Congenital Abnormality
In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.
Patent foramen ovale
MedGen UID:
8891
Concept ID:
C0016522
Congenital Abnormality
Failure of the foramen ovale to seal postnatally, leaving a potential conduit between the left and right cardiac atria.
Small for gestational age
MedGen UID:
65920
Concept ID:
C0235991
Finding
Smaller than normal size according to sex and gestational age related norms, defined as a weight below the 10th percentile for the gestational age.
Failure to thrive
MedGen UID:
746019
Concept ID:
C2315100
Disease or Syndrome
Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.
Feeding difficulties
MedGen UID:
65429
Concept ID:
C0232466
Finding
Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.
Poor suck
MedGen UID:
324693
Concept ID:
C1837142
Finding
An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed.
Sensorineural hearing loss disorder
MedGen UID:
9164
Concept ID:
C0018784
Disease or Syndrome
A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.
Abnormal pinna morphology
MedGen UID:
167800
Concept ID:
C0857379
Congenital Abnormality
An abnormality of the pinna, which is also referred to as the auricle or external ear.
Lethargy
MedGen UID:
7310
Concept ID:
C0023380
Sign or Symptom
A state of fatigue, either physical or mental slowness and sluggishness, with difficulties in initiating or performing simple tasks. Distinguished from apathy which implies indifference and a lack of desire or interest in the task. A person with lethargy may have the desire, but not the energy to engage in personal or socially relevant tasks.
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.
Prolonged partial thromboplastin time
MedGen UID:
66815
Concept ID:
C0240671
Finding
Increased time to coagulation in the partial thromboplastin time (PTT) test, a measure of the intrinsic and common coagulation pathways. Phospholipid, and activator, and calcium are mixed into an anticoagulated plasma sample, and the time is measured until a thrombus forms.
Hereditary antithrombin deficiency
MedGen UID:
75781
Concept ID:
C0272375
Disease or Syndrome
Deficiency of antithrombin III is a major risk factor for venous thromboembolic disease. Two categories of AT-III deficiency have been defined on the basis of AT-III antigen levels in the plasma of affected individuals. The majority of AT-III deficiency families belong in the type I (classic) deficiency group and have a quantitatively abnormal phenotype in which antigen and heparin cofactor levels are both reduced to about 50% of normal. The second category of AT-III deficiency has been termed type II (functional) deficiency. Affected individuals from these kindreds produce dysfunctional AT-III molecules; they have reduced heparin cofactor activity levels (about 50% of normal) but levels of AT-III antigen are often normal or nearly normal (summary by Bock and Prochownik, 1987). The 2 categories of antithrombmin III deficiency have been classified further. Type I (low functional and immunologic antithrombin) has been subdivided into subtype Ia (reduced levels of normal antithrombin), and type Ib (reduced levels of antithrombin and the presence of low levels of a variant). Type II (low functional but normal immunologic antithrombin) has been subdivided into subtype IIa (functional abnormalities affecting both the reactive site and the heparin-binding site of AT3); subtype IIb (functional abnormalities limited to the reactive site); and subtype IIc (functional abnormalities limited to the heparin-binding site) (summary by Lane et al., 1992).
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.
Short ribs
MedGen UID:
98094
Concept ID:
C0426817
Finding
Reduced rib length.
Progressive microcephaly
MedGen UID:
340542
Concept ID:
C1850456
Anatomical Abnormality
Progressive microcephaly is diagnosed when the head circumference falls progressively behind age- and gender-dependent norms.
Generalized hypotonia
MedGen UID:
346841
Concept ID:
C1858120
Finding
Generalized muscular hypotonia (abnormally low muscle tone).
Butterfly vertebrae
MedGen UID:
1744309
Concept ID:
C5438458
Congenital Abnormality
A butterfly vertebra (sagittal cleft vertebra or anterior rachischisis) is a sagittal defect in the vertebral body caused by failure of fusion of the two lateral chondrification centers during embryogenesis. The name is based on the appearance of the two hemivertebrae emerging as butterfly wings from the central cleft on x-ray.
Respiratory distress
MedGen UID:
96907
Concept ID:
C0476273
Sign or Symptom
Respiratory distress is objectively observable as the physical or emotional consequences from the experience of dyspnea. The physical presentation of respiratory distress is generally referred to as labored breathing, while the sensation of respiratory distress is called shortness of breath or dyspnea.
Recurrent upper respiratory tract infections
MedGen UID:
154380
Concept ID:
C0581381
Disease or Syndrome
An increased susceptibility to upper respiratory tract infections as manifested by a history of recurrent upper respiratory tract infections (running ears - otitis, sinusitis, pharyngitis, tonsillitis).
Recurrent pneumonia
MedGen UID:
195802
Concept ID:
C0694550
Disease or Syndrome
An increased susceptibility to pneumonia as manifested by a history of recurrent episodes of pneumonia.
Decreased circulating IgA concentration
MedGen UID:
57934
Concept ID:
C0162538
Disease or Syndrome
Decreased levels of immunoglobulin A (IgA).
Decreased circulating total IgM
MedGen UID:
116095
Concept ID:
C0239989
Finding
An abnormally decreased level of immunoglobulin M (IgM) in blood.
Decreased circulating IgG concentration
MedGen UID:
1720114
Concept ID:
C5234937
Finding
An abnormally decreased level of immunoglobulin G (IgG) in blood.
Edema
MedGen UID:
4451
Concept ID:
C0013604
Pathologic Function
An abnormal accumulation of fluid beneath the skin, or in one or more cavities of the body.
Hypocalcemia
MedGen UID:
5705
Concept ID:
C0020598
Disease or Syndrome
An abnormally decreased calcium concentration in the blood.
Hypoglycemia
MedGen UID:
6979
Concept ID:
C0020615
Disease or Syndrome
A decreased concentration of glucose in the blood.
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.
Wide nose
MedGen UID:
140869
Concept ID:
C0426421
Finding
Interalar distance more than two standard deviations above the mean for age, i.e., an apparently increased width of the nasal base and alae.
Epicanthus
MedGen UID:
151862
Concept ID:
C0678230
Congenital Abnormality
Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).
Triangular face
MedGen UID:
324383
Concept ID:
C1835884
Finding
Facial contour, as viewed from the front, triangular in shape, with breadth at the temples and tapering to a narrow chin.
Midface retrusion
MedGen UID:
339938
Concept ID:
C1853242
Anatomical Abnormality
Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle.
Short philtrum
MedGen UID:
350006
Concept ID:
C1861324
Finding
Distance between nasal base and midline upper lip vermilion border more than 2 SD below the mean. Alternatively, an apparently decreased distance between nasal base and midline upper lip vermilion border.
Thin upper lip vermilion
MedGen UID:
355352
Concept ID:
C1865017
Finding
Height of the vermilion of the upper lip in the midline more than 2 SD below the mean. Alternatively, an apparently reduced height of the vermilion of the upper lip in the frontal view (subjective).
Polyhydramnios
MedGen UID:
6936
Concept ID:
C0020224
Pathologic Function
The presence of excess amniotic fluid in the uterus during pregnancy.
Inversion of nipple
MedGen UID:
82844
Concept ID:
C0269269
Anatomical Abnormality
The presence of nipples that instead of pointing outward are retracted inwards.
Retinal detachment
MedGen UID:
19759
Concept ID:
C0035305
Disease or Syndrome
Primary or spontaneous detachment of the retina occurs due to underlying ocular disease and often involves the vitreous as well as the retina. The precipitating event is formation of a retinal tear or hole, which permits fluid to accumulate under the sensory layers of the retina and creates an intraretinal cleavage that destroys the neurosensory process of visual reception. Vitreoretinal degeneration and tear formation are painless phenomena, and in most cases, significant vitreoretinal pathology is found only after detachment of the retina starts to cause loss of vision or visual field. Without surgical intervention, retinal detachment will almost inevitably lead to total blindness (summary by McNiel and McPherson, 1971).
Esodeviation
MedGen UID:
1641033
Concept ID:
C4551734
Disease or Syndrome
A manifest or latent ocular deviation in which one or both eyes tends to deviate nasally.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
Follow this link to review classifications for ALG12-congenital disorder of glycosylation in Orphanet.

Recent clinical studies

Diagnosis

Scott TM, Campbell IM, Hernandez-Garcia A, Lalani SR, Liu P, Shaw CA, Rosenfeld JA, Scott DA
J Med Genet 2022 Mar;59(3):270-278. Epub 2021 Jan 18 doi: 10.1136/jmedgenet-2020-107317. PMID: 33461977Free PMC Article
Tahata S, Gunderson L, Lanpher B, Morava E
Mol Genet Metab 2019 Dec;128(4):409-414. Epub 2019 Aug 26 doi: 10.1016/j.ymgme.2019.08.007. PMID: 31481313

Clinical prediction guides

Scott TM, Campbell IM, Hernandez-Garcia A, Lalani SR, Liu P, Shaw CA, Rosenfeld JA, Scott DA
J Med Genet 2022 Mar;59(3):270-278. Epub 2021 Jan 18 doi: 10.1136/jmedgenet-2020-107317. PMID: 33461977Free PMC Article

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