Metachromatic Leukodystrophy (MLD) is characterized by loss of motor and intellectual functions. There are three clinical subtypes: late-infantile MLD (50-60%), juvenile MLD (20-30%) and adult MLD (15-20%). It is caused by a deficiency of the arylsulfatase A (ARSA) gene which leads to an impaired breakdown of sulfatides, sulfate-containing lipids that occur throughout the body and are in the highest abundance in the nervous tissue, kidneys and testes. Sulfatide accumulation in the nervous system leads to myelin breakdown or leukodystrohy. This disease is inherited in an autosomal recessive manner.

Reasons for Referral:

• Confirmation of clinical diagnosis of Metachromatic Leukodystrophy.
• Carrier testing for individuals with a positive family history for an ARSA point mutation (molecular analysis of the affected relative is recommended).
• Prenatal diagnosis (known mutations only).

Testing Methodology:

PCR amplification of the exons contained in the ARSA gene coding region will be performed on patient genomic DNA. Direct sequencing of amplification products is performed in both the forward and reverse directions using automated fluorescence dideoxy sequencing methods.

Specimen Requirements:

Blood: EDTA (purple-top) tubes: Adults: 14 cc; Child: 6 cc; Infant: 2-3 cc
Requisition form must accompany the specimen. Prior to any genetic testing, we recommend genetic counseling and we request that the subject sign our consent statement and submit it with the sample. To receive forms, additional information or specimen collection kits, please contact the laboratory. Please call laboratory for specific requirements for prenatal testing.

Turnaround Time:

Index: 4 weeks

CPT Codes and Prices:

Index: 83891, 83898x6, 83894, 83904x12, 83909x12, 83912
Known Familial Mutation: 83891, 83898, 83894, 83904x2, 83909x2, 83912

References:

1. Berger J, Loschl B, Bernheimer H, Lugowska A, Tylki-Szymanska A, Gieselmann V, Molzer B. Occurrence, distribution, and phenotype of arylsulfatase A mutations in patients with metachromatic leukodystrophy. Am. J. Med. Genet. 1997; 69: 335–40.

Shipping Information

Forms:

 >> Gene Sequencing Requisition
 >> Prenatal Requisition

Test Codes:

Index: 6380
Known Familial Mutation: 6381
Prenatal (Known Familial Mutation Only): 6382

Medical Genetics Laboratories
Baylor College of Medicine · Houston, TX 77030
Phone: 1-800-411-GENE · Fax: 713-798-6584
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