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Leukodystrophy, hypomyelinating, 26, with chondrodysplasia(HLD26)

MedGen UID:
1840948
Concept ID:
C5830312
Disease or Syndrome
Synonyms: CHONDRODYSPLASIA WITH HYPOMYELINATING LEUKODYSTROPHY; HLD26
 
Gene (location): SLC35B2 (6p21.1)
 
Monarch Initiative: MONDO:0859518
OMIM®: 620269

Definition

Hypomyelinating leukodystrophy-26 with chondrodysplasia (HLD26) is characterized by severe psychomotor delay, predominantly involving motor and expressive language development, with cerebral and cerebellar atrophy and corpus callosum hypoplasia. In addition, patients show pre- and postnatal growth retardation, early-onset scoliosis, and dislocations of large joints (Guasto et al., 2022). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see HLD1 (312080). [from OMIM]

Clinical features

From HPO
Knee dislocation
MedGen UID:
102364
Concept ID:
C0159970
Injury or Poisoning
Slippage of the FEMUR off the TIBIA.
Coxa valga
MedGen UID:
116080
Concept ID:
C0239137
Finding
Coxa valga is a deformity of the hip in which the angle between the femoral shaft and the femoral neck is increased compared to age-adjusted values (about 150 degrees in newborns gradually reducing to 120-130 degrees in adults).
Thumbs, congenital Clasped
MedGen UID:
98140
Concept ID:
C0431886
Congenital Abnormality
In the resting position, the tip of the thumb is on, or near, the palm, close to the base of the fourth or fifth finger.
Advanced ossification of carpal bones
MedGen UID:
341422
Concept ID:
C1849292
Finding
Ossification of carpal bones at an abnormally early age.
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).
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.
Leukodystrophy
MedGen UID:
6070
Concept ID:
C0023520
Disease or Syndrome
Leukodystrophy refers to deterioration of white matter of the brain resulting from degeneration of myelin sheaths in the CNS. Their basic defect is directly related to the synthesis and maintenance of myelin membranes. Symmetric white matter involvement at MRI is a typical finding in patients with leukodystrophies.
Cerebral atrophy
MedGen UID:
116012
Concept ID:
C0235946
Disease or Syndrome
Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum.
Hypoplasia of the corpus callosum
MedGen UID:
138005
Concept ID:
C0344482
Congenital Abnormality
Underdevelopment of the corpus callosum.
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.
Cerebellar atrophy
MedGen UID:
196624
Concept ID:
C0740279
Disease or Syndrome
Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.
Limb dystonia
MedGen UID:
152944
Concept ID:
C0751093
Sign or Symptom
A type of dystonia (abnormally increased muscular tone causing fixed abnormal postures) that affects muscles of the limbs.
Absent speech
MedGen UID:
340737
Concept ID:
C1854882
Finding
Complete lack of development of speech and language abilities.
Delayed CNS myelination
MedGen UID:
867393
Concept ID:
C4021758
Anatomical Abnormality
Delayed myelination in the central nervous system.
Thin corpus callosum
MedGen UID:
1785336
Concept ID:
C5441562
Anatomical Abnormality
An abnormally thin corpus callous, due to atrophy, hypoplasia or agenesis. This term is intended to be used in situations where it is not known if thinning of the corpus callosum (for instance, as visualized by magnetic resonance tomography) is due to abnormal development (e.g. a leukodystrophy) or atrophy following normal development (e.g. neurodegeneration).
Retrognathia
MedGen UID:
19766
Concept ID:
C0035353
Congenital Abnormality
An abnormality in which the mandible is mislocalised posteriorly.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Hypoplastic cervical vertebrae
MedGen UID:
372079
Concept ID:
C1835570
Finding
Joint hypermobility
MedGen UID:
336793
Concept ID:
C1844820
Finding
The capability that a joint (or a group of joints) has to move, passively and/or actively, beyond normal limits along physiological axes.
Small epiphyses
MedGen UID:
339612
Concept ID:
C1846803
Finding
Reduction in the size or volume of epiphyses.
Axial hypotonia
MedGen UID:
342959
Concept ID:
C1853743
Finding
Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.
Short long bone
MedGen UID:
344385
Concept ID:
C1854912
Finding
One or more abnormally short long bone.
Elbow dislocation
MedGen UID:
404765
Concept ID:
C2720437
Injury or Poisoning
Dislocation of the distal humerus out of the elbow joint, where the radius, ulna, and humerus meet.
Lumbar scoliosis
MedGen UID:
412568
Concept ID:
C2748518
Finding
Isolated Pierre-Robin syndrome
MedGen UID:
19310
Concept ID:
C0031900
Congenital Abnormality
Pierre Robin sequence is a craniofacial anomaly comprising mandibular hypoplasia, cleft secondary palate, and glossoptosis leading to life-threatening obstructive apnea and feeding difficulties during the neonatal period (summary by Tan et al., 2013).
Glossoptosis
MedGen UID:
78623
Concept ID:
C0267048
Disease or Syndrome
Posterior displacement of the tongue into the pharynx, i.e., a tongue that is mislocalised posteriorly.
Flat face
MedGen UID:
342829
Concept ID:
C1853241
Finding
Absence of concavity or convexity of the face when viewed in profile.
Cleft palate
MedGen UID:
756015
Concept ID:
C2981150
Congenital Abnormality
Cleft palate is a developmental defect of the palate resulting from a failure of fusion of the palatine processes and manifesting as a separation of the roof of the mouth (soft and hard palate).
Horizontal nystagmus
MedGen UID:
124399
Concept ID:
C0271385
Disease or Syndrome
Nystagmus consisting of horizontal to-and-fro eye movements.

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