Adenosine Monophosphate Deaminase (AMPD) Deficiency, Erythrocytic: AMPD3 Gene Sequencing

Condition Description

Adenosine monophosphate deaminase (AMPD) is found in muscle, liver, and erythrocytes.  The AMPD3 gene (11p15.4) encodes the AMPD found in erythrocytes.  Individuals with two mutations in their AMPD3 gene are healthy and have no hematologic disorders.  Their ATP levels were approximately 150% higher in the AMPD deficient red cells when compared with control cells.  Additionally, degradation of the adenine nucleotide was slower in the deficient red cells when compared with control cells.  AMPD deficiency is inherited in an autosomal recessive pattern. 

For patients with suspected AMPD deficiency, sequence analysis is recommended as the first step in mutation identification. For patients in whom mutations are not identified by full gene sequencing, deletion/duplication analysis is appropriate.

References:
  • Yamada et al. (1994). Human Molecular Genetics, 3:331-334.
  • OMIM #612874: AMPD deficiency, erythrocytic
  • OMIM #102772: AMPD3 gene

Genes (1)

Indications

This test is indicated for:
  • Confirmation of a clinical diagnosis of adenosine monophosphate deaminase deficiency, erythrocytic.
  • Carrier testing in adults with a family history of adenosine monophosphate deaminase deficiency, erythrocytic.

Methodology

PCR amplification of 14 exons contained in the AMPD3 gene is performed on the patient's genomic DNA. Direct sequencing of amplification products is performed in both forward and reverse directions, using automated fluorescence dideoxy sequencing methods. The patient's gene sequences are then compared to a normal reference sequence. Sequence variations are classified as mutations, benign variants unrelated to disease, or variations of unknown clinical significance. Variants of unknown clinical significance may require further studies of the patient and/or family members. This assay does not interrogate the promoter region, deep intronic regions, or other regulatory elements, and does not detect large deletions.

Detection

Clinical Sensitivity: Unknown. Mutations in the promoter region, some mutations in the introns and other regulatory element mutations cannot be detected by this analysis. Large deletions will not be detected by this analysis. Results of molecular analysis should be interpreted in the context of the patient's clinical and/or biochemical phenotype.

Analytical Sensitivity: ~99%

Specimen Requirements

Listed below are EGL's preferred sample criteria. For any questions, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (eglgc@egl-eurofins.com).
Submit only 1 of the following specimen types
Whole Blood (EDTA)
WBP

Requirements
EDTA (Purple Top)
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Collection and Shipping
Ship sample at room temperature for receipt at EGL within 72 hours of collection. Do not freeze.
DNA, Isolated
DNA

Requirements
Microtainer
8µg
Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Collection and Shipping
Refrigerate until time of shipment in 100 ng/µL in TE buffer. Ship sample at room temperature with overnight delivery.
Saliva
SLV

Requirements
Oragene™ Saliva Collection Kit
Orangene™ Saliva Collection Kit used according to manufacturer instructions. Please contact EGL for a Saliva Collection Kit for patients that cannot provide a blood sample.
Collection and Shipping
Please do not refrigerate or freeze saliva sample. Please store and ship at room temperature.
  • Deletion/duplication analysis of the AMPD3 gene by CGH array is available for those individuals in whom sequence analysis is negative.
  • Sequencing and deletion/duplication analysis of the AMPD1 gene are available.
  • Custom diagnostic mutation analysis (KM) is available to family members if mutations are identified by targeted mutation testing or sequencing analysis.
  • Prenatal testing is available only for known familial mutations to individuals who are confirmed carriers of mutations. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.

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