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Congenital disorder of glycosylation, type iit(CDGIIt; CDG2T)

MedGen UID:
1709627
Concept ID:
C5394387
Disease or Syndrome
Synonym: CDG IIt
 
Gene (location): GALNT2 (1q42.13)
 
Monarch Initiative: MONDO:0030043
OMIM®: 618885

Definition

Congenital disorder of glycosylation type IIt (CDG2t) is an autosomal recessive multisystemic metabolic disorder characterized by global developmental delay, poor overall growth, severely impaired intellectual development with absent language, and behavioral abnormalities. Most patients develop early-onset seizures; brain imaging tends to show white matter abnormalities. Variable dysmorphic features, including long face, almond-shaped eyes, protruding maxilla, and short philtrum, are also present. The disorder, which is associated with low levels of HDL cholesterol, results from defective posttranslational O-linked glycosylation of certain plasma lipids and proteins (summary by Zilmer et al., 2020). For an overview of congenital disorders of glycosylation, see CDG1A (212065) and CDG2A (212066). [from OMIM]

Clinical features

From HPO
Urinary incontinence
MedGen UID:
22579
Concept ID:
C0042024
Finding
Loss of the ability to control the urinary bladder leading to involuntary urination.
Small hand
MedGen UID:
108279
Concept ID:
C0575802
Finding
Disproportionately small hand.
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 foot
MedGen UID:
376415
Concept ID:
C1848673
Finding
A measured foot length that is more than 2 SD below the mean for a newborn of 27 - 41 weeks gestation, or foot that is less than the 3rd centile for individuals from birth to 16 years of age (objective). Alternatively, a foot that appears disproportionately short (subjective).
Short stature
MedGen UID:
87607
Concept ID:
C0349588
Finding
A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).
Constipation
MedGen UID:
1101
Concept ID:
C0009806
Sign or Symptom
Infrequent or difficult evacuation of feces.
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.
Conductive hearing impairment
MedGen UID:
9163
Concept ID:
C0018777
Disease or Syndrome
An abnormality of vibrational conductance of sound to the inner ear leading to impairment of sensory perception of sound.
Low-set ears
MedGen UID:
65980
Concept ID:
C0239234
Congenital Abnormality
Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.
Posteriorly rotated ears
MedGen UID:
96566
Concept ID:
C0431478
Congenital Abnormality
A type of abnormal location of the ears in which the position of the ears is characterized by posterior rotation (the superior part of the ears is rotated towards the back of the head, and the inferior part of the ears towards the front).
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.
Intellectual disability, severe
MedGen UID:
48638
Concept ID:
C0036857
Mental or Behavioral Dysfunction
Severe mental retardation is defined as an intelligence quotient (IQ) in the range of 20-34.
Delayed ability to walk
MedGen UID:
66034
Concept ID:
C0241726
Finding
A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.
Delayed speech and language development
MedGen UID:
105318
Concept ID:
C0454644
Finding
A degree of language development that is significantly below the norm for a child of a specified age.
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.
Autistic behavior
MedGen UID:
163547
Concept ID:
C0856975
Mental or Behavioral Dysfunction
Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior.
Insomnia
MedGen UID:
214589
Concept ID:
C0917801
Sign or Symptom
Persistent difficulty initiating or maintaining sleep.
Abnormal cerebral white matter morphology
MedGen UID:
181756
Concept ID:
C0948163
Pathologic Function
An abnormality of the cerebral white matter.
Reduced eye contact
MedGen UID:
303190
Concept ID:
C1445953
Finding
A reduced frequency or duration of eye contact.
Delayed gross motor development
MedGen UID:
332508
Concept ID:
C1837658
Finding
A type of motor delay characterized by a delay in acquiring the ability to control the large muscles of the body for walking, running, sitting, and crawling.
Multifocal seizures
MedGen UID:
482664
Concept ID:
C3281034
Finding
Seizures that start from several different areas of the brain (i.e., with multiple ictal onset locations).
Delayed ability to sit
MedGen UID:
1368737
Concept ID:
C4476710
Finding
A failure to achieve the ability to sit at an appropriate developmental stage. Most children sit with support at 6 months of age and sit steadily without support at 9 months of age.
Iron deficiency anemia
MedGen UID:
57668
Concept ID:
C0162316
Disease or Syndrome
Anemia caused by low iron intake, inefficient iron absorption in the gastrointestinal tract, or chronic blood loss.
Brachycephaly
MedGen UID:
113165
Concept ID:
C0221356
Congenital Abnormality
An abnormality of skull shape characterized by a decreased anterior-posterior diameter. That is, a cephalic index greater than 81%. Alternatively, an apparently shortened anteroposterior dimension (length) of the head compared to width.
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.
Decreased circulating vitamin D concentration
MedGen UID:
12114
Concept ID:
C0042870
Disease or Syndrome
The concentration of vitamin D in the blood circulation is below the lower limit of normal.
Decreased HDL cholesterol concentration
MedGen UID:
57731
Concept ID:
C0151691
Finding
An decreased concentration of high-density lipoprotein cholesterol in the blood.
Decreased serum creatinine
MedGen UID:
488901
Concept ID:
C0428282
Finding
An abnormally reduced amount of creatinine in the blood.
Hypotriglyceridemia
MedGen UID:
488913
Concept ID:
C0542037
Disease or Syndrome
An decrease in the level of triglycerides in the blood.
Abnormal protein O-linked glycosylation
MedGen UID:
868534
Concept ID:
C4022933
Anatomical Abnormality
An anomaly of protein O-linked glycosylation, i.e., of the process in which a carbohydrate or carbohydrate derivative unit is added to a protein via the hydroxyl group of a serine or threonine residue.
High forehead
MedGen UID:
65991
Concept ID:
C0239676
Finding
An abnormally increased height of the forehead.
Downslanted palpebral fissures
MedGen UID:
98391
Concept ID:
C0423110
Finding
The palpebral fissure inclination is more than two standard deviations below the mean.
Long face
MedGen UID:
324419
Concept ID:
C1836047
Finding
Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (subjective).
Thick vermilion border
MedGen UID:
332232
Concept ID:
C1836543
Finding
Increased width of the skin of vermilion border region of upper lip.
Tented upper lip vermilion
MedGen UID:
326574
Concept ID:
C1839767
Finding
Triangular appearance of the oral aperture with the apex in the midpoint of the upper vermilion and the lower vermilion forming the base.
Prominent nasal bridge
MedGen UID:
343051
Concept ID:
C1854113
Finding
Anterior positioning of the nasal root in comparison to the usual positioning for age.
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.
Pineal cyst
MedGen UID:
235476
Concept ID:
C1335411
Finding
A glial uniloculated or multiloculated fluid-filled sac that either reside within or completely replace the pineal gland.
Astigmatism
MedGen UID:
2473
Concept ID:
C0004106
Disease or Syndrome
Astigmatism (from the Greek 'a' meaning absence and 'stigma' meaning point) is a condition in which the parallel rays of light entering the eye through the refractive media are not focused on a single point. Both corneal and noncorneal factors contribute to refractive astigmatism. Corneal astigmatism is mainly the result of an aspheric anterior surface of the cornea, which can be measured readily by means of a keratometer; in a small fraction of cases (approximately 1 in 10) the effect is neutralized by the back surface. The curvature of the back surface of the cornea is not considered in most studies, because it is more difficult to measure; moreover, in the case of severe corneal astigmatism, there is evidence that both surfaces have the same configuration. Noncorneal factors are errors in the curvature of the 2 surfaces of the crystalline lens, irregularity in the refractive index of the lens, and an eccentric lens position. Since the cornea is the dominant component of the eye's refracting system, a highly astigmatic cornea is likely to result in a similarly astigmatic ocular refraction (summary by Clementi et al., 1998).
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).
Nystagmus
MedGen UID:
45166
Concept ID:
C0028738
Disease or Syndrome
Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.
Alternating exotropia
MedGen UID:
101825
Concept ID:
C0152207
Disease or Syndrome
A type of exotropia in which either eye may be used for fixation.

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