Myotonic Dystrophy 1 (DMPK) genetic testing (repeat expansion)-994
Test info
Type 1 myotonic dystrophy results from a mutation in the DMPK gene known as a trinucleotide repeat expansion. This mutation increases in the size of the repeated CTG segment in the DMPK gene. People with type 1 myotonic dystrophy have from 50 to 5,000 CTG repeats in most cells. The number of repeats may be even greater in certain types of cells, such as muscle cells.
False positive or false negative results may occur for reasons that include insufficient information available about rare genetic variants, allele dropout, blood transfusions, bone marrow transplantation, somatic or tissue-specific mosaicism, or mislabeled samples. Maximum reportable size of repeat expansion testing: ATN1: 110 repeats; ATXN1: 150 repeats (repeats greater than 40 in the ATXN1 gene cannot be assessed for CAT interruptions); ATXN2: 150 repeats; ATXN3: 120 repeats; ATXN7: 125 repeats; ATXN8/ATXN8OS: 150 repeats; ATXN10: 70 repeats; C9orf72: 65 repeats; CACNA1A: 145 repeats; CNBP: 373 base pairs (approximately 75 repeats); DMPK: 150 repeats; FXN: 1300 repeats; HTT: 100 repeats; JPH3: 100 repeats; NOP56: 65 repeats; PPP2R2B: 150 repeats; TBP: 120 repeats. Repeat sizes greater than the maximum reportable range are reported as greater than the largest reportable repeat size. This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
Specimen
Immediately after collection, mix tube thoroughly by gentle inversion, 8 - 10 times, to prevent clotting
Lavender (EDTA), 4mL
Molecular Medicare Billing Request
Hospital clients submitting a request for this assay on an outpatient with Medicare should complete and submit a Molecular Medicare billing request form to notify us of the need for Allina Health Laboratory to bill insurance.
Ambient (preferred) - 14 days
Refrigerated – 30 days
Frozen – NO
- Frozen specimens
- Hemolyzed specimens
Performance
Repeat-Primed PCR and fragment length analysis to identify number of nucleotide repeats.
Clinical and Interpretive info
# of repeats
Maximum reportable sizing: 150 repeats
Billing
Hospital clients submitting a request for this assay on an outpatient with Medicare should complete and submit a Molecular Medicare billing request form to notify us of the need for Allina Health Laboratory to bill insurance.