DISEASE INFORMATION
Canavan Disease is an autosomal recessive neurodegenerative disease caused by mutations in the ASPA gene, which codes for the enzyme aspartoacylase. Deficiency of this enzyme causes accumulation of N-acetylaspartic acid in the central nervous system and disrupted myelination. Onset occurs in infancy with hypotonia, progressive loss of motor control, and macrocephaly. Most developmental milestones are not achieved and patients usually do not survive past childhood. Approximately 1/57 members of the Ashkenazi Jewish population carry a Canavan Disease mutation.¹ Three mutations account for 99% of those detected in this group but they are rare in other groups.² A fourth mutation accounts for approximately 50% of Canavan alleles in the non-Ashkenazi Jewish.^2-4 More than 50 disease-causing mutations, including gross deletions, have been reported.

TESTING BENEFITS & INDICATIONS
Molecular testing for a small number of mutations is highly sensitive in the Ashkenazi Jewish population, but not in other ethnic groups. Biochemical carrier screening is not available for screening purposes. The Canavan AMPLIFIED test provides a detection rate of ~99% across all ethnicities. This enables the greatest possible carrier risk reduction for high-risk or mixed-ethnicity couples, expands options for prenatal diagnosis, simplifies carrier testing in the extended family, and clarifies or confirms biochemical diagnoses. Indications for testing are:

• carrier testing for high-risk, anxious, or mixed-ethnicity couples
• prenatal diagnosis for known carrier couples
• mutation identification in affected patients

The following table shows revised or post-test carrier risks by ethnicity, assuming a negative Ambry Test result and no family history of the disease.

Ethnicity	Canavan Carrier Risk before Test	Revised Carrier Risk after Canavan AMPLIFIED
Ashkenazi Jewish	1/57	1/5601
Other populations at general risk	unknown; <1/57	<1/5601

TEST DESCRIPTION
The Canavan AMPLIFIED test includes double-stranded automated sequencing in sense and antisense directions of exons 1-6 of the ASPA gene, plus at least 20 bases into the 5’ and 3’ ends of all the introns. Concurrent analysis for gross deletions/duplications of any exon is performed by MLPA®. Specific mutation analysis for individual ASPA mutations known to be in the family is also available.

MUTATION DETECTION RATE
Approximately 99% of mutations are detectable by Canavan AMPLIFIED regardless of the patient’s ethnicity. 

SPECIMEN REQUIREMENTS
Blood: Collect 3-5 cc from adult or 2 cc minimum from child into EDTA purple-top tube (first choice) or ACD yellow-top tube (second choice). Store at room temperature or refrigerate. Ship at room temperature.
Blood Spot: Minimum of one complete spot approximately 0.5 inch in diameter on S&S 903 collection paper or similar. Store in a clean plastic bag at room temperature. Ship at room temperature.
Saliva: Collect 2 ml into Oragene™ DNA Self-Collection container. Store and ship at room temperature.
DNA: Send 20 µg in TE at 50-100 ng/µl. Store frozen and ship on ice or dry ice.
Prenatal: Prenatal testing is available. Please call an Ambry Genetic Counselor to discuss your case.

AMBRY PUBLICATIONS
Expanding the Options for Canavan Disease Testing in Non-Jewish Populations: Full Gene Analysis of ASPA
2006 Annual Meeting of the National Society of Genetic Counselors

REFERENCES
¹ Feigenbaum A et al. Am J Med Genet. 2004;124:142-147.
² Kaul R. et al. Am J Hum Genet. 1994;55:34-41.
³ Sistermans EA et al. Eur J Hum Genet. 2000;8:557-560.
⁴ Kaul R et al. Am J Hum Genet. 1996;59:95-102.

DISCLAIMER
This test was developed and its performance characteristics were determined by Ambry Genetics Corporation. The laboratory is regulated under the Clinical Laboratory Improvement Amendments 2003 as qualified to perform nonwaived testing. The Ambry Test: Canavan AMPLIFIED analyzes the following types of mutations: nucleotide substitutions, small deletions, small insertions, small indels, gross deletions, and gross duplications. It is not intended to analyze the following types of mutations: gross insertions, gene rearrangements, deep intronic variations, and other unknown abnormalities. The pattern of mutation types varies with the gene tested and the Ambry Test detects a high but variable percentage of known and unknown mutants of the classes stated. A negative result from the analysis cannot rule out the possibility that the tested individual carries a rare unexamined mutation or mutation in the undetectable group. The Ambry Test: Canavan AMPLIFIED is designed and validated to be capable of detecting about ~99% of Canavan Disease mutations, respectively (considering less than 1% being the other types of mutations). Canavan Disease is a complex clinical disorder, which in the majority of cases is due to alterations in the ASPA gene generally detected by The Ambry Test: Canavan AMPLIFIED except as noted above. Mutations in other genes or the regions not tested by The Ambry Test: Canavan AMPLIFIED can also give rise to clinical conditions similar or identical to Canavan Disease. Although molecular tests are highly accurate, rare diagnostic errors may occur. Possible diagnostic errors include sample mix-up, erroneous paternity identification, technical errors, clerical errors, and genotyping errors. Genotyping errors can result from trace contamination of PCR reactions, from maternal cell contamination in fetal samples, from rare genetic variants which interfere with analysis, or from other sources.  Result reports do not represent medical advice. Any questions, suggestions, or concerns regarding interpretation of results should be forwarded to a genetic counselor, medical geneticist, or physician skilled in interpretation of the relevant medical literature. References are available upon request.