METACHROMATIC LEUKODYSTROPHY (MLD) - Late Infantile
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ALTERNATE NAMES
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Arylsulfatase A Deficiency (ARSA); Cerebroside Sulfatase Deficiency; Metachromatic
Form of Diffuse Cerebral Sclerosis; Metachromatic Leukoencephalopathy; Scholz-Bielchowsky-Henneberg
Diffuse Cerebral Sclerosis; Scholz-Greenfield Disease; Sulphatide Lipidosis, Sulphatidosis;
Van Bogaert-Nijssen Disease
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DESCRIPTION
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Metachromatic leukodystrophy (MLD) is a hereditary degenerative disease transmitted as an autosomal recessive, due to
sulfatase A deficiency, with excess accumulation of sulfated lipids responsible for
metachromasia in various tissues. MLD impairs the growth or development of the myelin
sheath, the fatty covering that acts as an insulator around nerve fibers
Late infantile form, which is the most common form of MLD, usually begins in the second year of life
(ranges 1-3 years).
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DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING
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Diagnostic testing: Diagnosis of MLD includes:
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Magnetic resonance imaging (MRI) to identify lesions and atrophy in the white matter
of the brain;
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Urine tests usually show elevated sulfatide levels;
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Some psychiatric disorders coupled with difficulty walking or muscle wasting; and
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Blood testing can show a reduced activity of the ARSA enzyme.
Deficiency of the ARSA enzyme alone is not proof of MLD, because a substantial ARSA
deficiency without any symptoms or clinical consequences is frequent in the general
population. During diagnosis and genetic counseling, these harmless ARSA enzyme deficiencies
must be distinguished from those causing MLD. The only diagnostic test that solves
this problem and is definitive for MLD diagnosis is analysis of the genetic mutation.
Physical findings: After normal early development, the infant displays:
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Developmental milestones, such as language development, are not met;
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Some children may become comatose.
ICD-9: 330.0
ICD-10: E75.25
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PROGRESSION
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No effective treatment is available to reverse the course of MLD. Drug therapy is
part of supportive care for symptoms such as behavioral disturbances, feeding difficulties,
seizures, and constipation. Bone marrow transplantation has been tried and there is
evidence that this treatment might slow the progression of the disease. In infants,
during a symptom-free phase of the late infantile form, neurocognitive function may
be stabilized, but the symptoms of motor function loss progress.
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TREATMENT
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The prognosis for MLD is poor. In young children with MLD late infantile form, progressive
loss of motor and cognitive functions is rapid. Death usually results within five
years after the onset of clinical symptoms.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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Suggested MER for Evaluation:
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Genetic testing of ARSA gene (targeted mutation or sequence analysis;
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Elevation of sulfatides (10 to 100 times normal) in 24-hour urine, enzyme assay for
ARSA enzyme activity; and
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MRI or CAT scan with characteristic white matter abnormalities and description of
associated clinical findings (muscle weakness or wasting, rigidity developmental delays).
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Suggested Listings for Evaluation:
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DETERMINATION
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LISTING
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REMARKS
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Meets
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110.08
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Late infantile form of MLD confirmed by genetic testing or elevated sulfatides in
24-hour urine.
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111.17
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Equals
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or the
listings suggested to evaluate the claim. However, the decision to allow or deny the
claim rests with the adjudicator.
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