Metachromatic Leukodystrophy (MLD)
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(Adapted from Pocket Guide to Alaska Native Pediatric Diagnoses)
Pathophysiology: Lysosomal storage disease causing progressive demyelination of central and peripheral nervous sytem, also affecting kidneys and other visceral organs due to accumulation of cerebroside sulfate
Inheritance: Autosomal recessive
Demographics:
- 1:2,500 in Navajo (closely related to Athabascan)
- 1:40,000-1:100,000 in northern Europe and North America
Signs/Symptoms:
- Children have normal development until onset of disease
- Late infantile onset = 6m/o - 2y/o (up to 4y/o). regression of motor skills, gait difficulties, seizures, ataxia, hypotonia, extensor plantar responses, optic atrophy, fussiness/pain/distress - thought to be due to neuropathy or dystonia
- Juvenile and adult onset => 4y/o. gait disturbance, ataxia, seizures, intellectual impairment, behavioral difficulties, upper motor neuron signs, peripheral neuropathy
Diagnosis:
- Brain MRI: symmetric white matter lesions with periventricular predominance (early) and cortical atrophy (late)
- Genetic testing for deficient ARSA (arylsulfatase A) gene activity
- Option 1: blood draw 6-8mL green top (min 2mL) plus optional 1-2mL lavender top for DNA extraction if worried about aged specimens
- Option 2: blood spots on PKU card
Management:
- Consult YKHC on call Pediatrician and assign CPP status
- refer to Pediatric Neurology
- no curative treatment
- Bone marrow transplant, gene therapy and hematopoietic stem cell transplant are all investigational with goal of slowing the disease course
- Prognosis for late infantile and early juvenile onset is poor (death within 5 to 6 years)
Critical Times for Affected Patients:
- Recognition of symptoms and accurate diagnosis
Resources/References
- National Library of Medicine Genetics Home Reference: http://ghr.nlm.nih.gov/condition/metachromatic-leukodystrophy
- United Leukodystrophy Foundation Fact Sheet — Metachromatic Leukodystrophy (MLD)
- Metachromatic Leukodystrophy among southern Alaskan Eskimos: molecular and genetic studies -- N.M. Pastor-Soler, et al