Hypomyelination with Brain stem and Spinal cord involvement and Leg spasticity (HBSL)

Also known as

  • Leukodystrophy Hypomyelination Leukoencephalopathy

HBSL is a progressive inherited white matter disease (also called Leukoencephalopathy) that affects the brain and spinal cord. Leukoencephalopathy refers to a group of genetic disorders characterised by imperfect myelin, which is the fatty covering that insulates nerve fibres.

Condition details

The signs and symptoms of this disease usually begin in early infancy; however, the course of the condition appears to be quite variable. Infants with HBSL typically appear normal for the first few months of life and between 6 to 18 months begin having problems with development, including decreased muscle tone (hypotonia), a delay or regression in motor skills such as turning over, crawling, controlling head movement, and sitting without support. In addition, affected individuals develop abnormal muscle stiffness (spasticity) especially of their legs and difficulty with coordinating movements (ataxia). These movement problems affect the legs more than the arms, making walking difficult. Some affected individuals develop recurrent seizures (epilepsy), speech difficulties (dysarthria), learning problems, or mild deterioration of mental functioning. Several children experienced sudden deterioration with minor infections or after vaccination with slow recovery.

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Photos of affected individuals

Click images to enlarge.

  • No baby imageBaby
  • No toddler imageToddler
  • No child 4-10 imageChild 4-10
  • No child 10-18 imageChild 10-18
  • No adult imageAdult

Typical age range of first manifestation

  • Can manifest in Baby
  • Can manifest in Toddler
  • Can manifest in Child 4-10
  • Can manifest in Child 10-18
  • Does not manifest in Adult

Symptoms

Baby
Lay terms Clinical terms
  • Problems with development
  • including decreased muscle tone (hypotonia)
  • a delay or regression in motor skills such as turning over
  • crawling
  • controlling head movement
  • and sitting without support. In addition
  • affected individuals develop abnormal muscle stiffness (spasticity) especially of their legs and difficulty with coordinating movements (ataxia). These movement problems affect the legs more than the arms
  • making walking difficult. Some affected individuals develop recurrent seizures (epilepsy)
  • speech difficulties (dysarthria)
  • learning problems
  • or mild deterioration of mental functioning.
Toddler
Lay terms Clinical terms
  • Problems with development
  • including decreased muscle tone (hypotonia)
  • a delay or regression in motor skills such as turning over
  • crawling
  • controlling head movement
  • and sitting without support. In addition
  • affected individuals develop abnormal muscle stiffness (spasticity) especially of their legs and difficulty with coordinating movements (ataxia). These movement problems affect the legs more than the arms
  • making walking difficult. Some affected individuals develop recurrent seizures (epilepsy)
  • speech difficulties (dysarthria)
  • learning problems
  • or mild deterioration of mental functioning.
Child 4-10
Lay terms Clinical terms
  • Problems with development
  • including decreased muscle tone (hypotonia)
  • a delay or regression in motor skills such as turning over
  • crawling
  • controlling head movement
  • and sitting without support. In addition
  • affected individuals develop abnormal muscle stiffness (spasticity) especially of their legs and difficulty with coordinating movements (ataxia). These movement problems affect the legs more than the arms
  • making walking difficult. Some affected individuals develop recurrent seizures (epilepsy)
  • speech difficulties (dysarthria)
  • learning problems
  • or mild deterioration of mental functioning.
Child 10-18
Lay terms Clinical terms
  • Problems with development
  • including decreased muscle tone (hypotonia)
  • a delay or regression in motor skills such as turning over
  • crawling
  • controlling head movement
  • and sitting without support. In addition
  • affected individuals develop abnormal muscle stiffness (spasticity) especially of their legs and difficulty with coordinating movements (ataxia). These movement problems affect the legs more than the arms
  • making walking difficult. Some affected individuals develop recurrent seizures (epilepsy)
  • speech difficulties (dysarthria)
  • learning problems
  • or mild deterioration of mental functioning.

Affected genes identified to date

  • DARS

Inheritance patterns

Is Autosomal recessive

HBSL is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. In this condition, each copy of the gene carries the same homozygous mutations or different compound heterozygous mutations.

Are carriers affected?

No

How many are affected?

Unknown

Support groups and organisations

Mr Stephen Damiani
Mission Massimo Foundation
24 Villiers Street
Elsternwick
Victoria
3185
Australia
Tel +61395231996
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Known experts

Dr Adeline Vanderver
Field of interestPaediatric Neurology
Children's National Hospital
111 Michigan Ave NW
Washington
District of Columbia
20310
United States
Tel +12024766230
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