Contents
Autosomal-recessive inherited lysosomal storage disorder (LSD), characterized by the deficiency of the enzyme arylsulfatase-A (ARSA), or, more rarely, of its activator protein saposin-B.
Presentation
Late-infantile MLD (present at 0-3 years):
- Irritability
- Developmental delay
Juvenile MLD (present at 4 year-adolescence):
- Behavioural changes
- ↓ ability in school
Adult MLD (present after 16 years):
- Memory loss
- Psychosis
Complications:
All forms of MLD progress to any of the following:
- Blindness
- Paralysis
- Unresponsiveness
- Dementia
- Psychosis
Diagnosis
Blood investigations:
- Arylsulfatase A (ARSA) enzyme activity in WBC
- Urine sulfatide levels
Genetic testing:
- ARSA gene
- PSAP gene
Brain MRI:
- Hyperintensification of white matter regions (indicates loss of myelin)
Management
Supportive management