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2015: Mingie (TYMP) Sequencing

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Test Code Test Name Turnaround Blood Sample Tissue Sample CPT Codes 2015 CPT Codes 2013
2015 TYMP 3 weeks $1,000.00 $1,100.00 81405 81479
Mingie

Selecting the Appropriate Sample Type

Condition/Phenotype:

 Mitochondrial DNA depletion syndrome 6 (hepatocerebral type) (OMIM 256810)

 

Testing Method:

Sanger Sequencing of TYMP gene.

 

TYMP

Mitochondrial neurogastro intestinal encephalopathy (MINGIE) is a multi-organ affected condition, particularly the gastrointestinal (GI) system and nervous system[1, 2]. For the GI system, primary feature is gastrointestinal dysmotility, which may result in poor appetite, dysphagia, nausea, vomiting, stomach pain, diarrhea, constipation, and weight loss. Reduced muscle mass secondary to malnutrition may also occur. Neurologically, affected individuals may experience numbness or weakness of limbs, which is a typical presentation of peripheral neuropathy. Some patients may also present with ptosis, ophthalmoplegia, and hearing loss. The typical finding of brain MRI is white matter abnormalities as leukoencephalopathy.

MNGIE is an autosomal recessive condition. Mutations of the TYMP gene, also known as the ECGF1 gene, is the most common genetic cause for this condition. TYMP is located on chromosome 22 and encodes thymidine phosphorylase. This enzyme is required for breakdown of thymidine[3, 4]. In patients with mutation of TYMP, reduced or no enzymatic activity is noted, which leads to accumulation of thymidine. Thymidine is a substrate for DNA synthesis. Therefore, mutations of TYMP can affect mitochondria DNA synthesis, resulting in malfunction of mitochondria.

References

1. Hirano, M., et al., Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): clinical, biochemical, and genetic features of an autosomal recessive mitochondrial disorder. Neurology, 1994. 44(4): p. 721-7.

2. Nishino, I., et al., Mitochondrial neurogastrointestinal encephalomyopathy: an autosomal recessive disorder due to thymidine phosphorylase mutations. Ann Neurol, 2000. 47(6): p. 792-800.

3. Spinazzola, A., et al., Altered thymidine metabolism due to defects of thymidine phosphorylase. J Biol Chem, 2002. 277(6): p. 4128-33.

4. Usuki, K., et al., Platelet-derived endothelial cell growth factor has thymidine phosphorylase activity. Biochem Biophys Res Commun, 1992. 184(3): p. 1311-6.


Specimen requirements:

Acceptable specimen types for this test: Whole blood, saliva, buccal swabs, culture cells, muscle tissue.

See more details on sample requirements here