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201904151249411

GNAS-COLD-MAMAPCR real time

Quantification assay of McCune-Albright syndrome (MAS)          cod. BM-004

 

Principle of the test: Quantify low frequencies of GNAS mutations

Technology: COLD-MAMA-PCR

Gene Target: GNAS

Specimen: DNA

Limit of detection: 0.625%

Dynamic Range of quantification: 2.5% < x < 40%

Controls included: Yes

Reporting Units: % mutant alleles

Number of tests: 25 tests BM-004 

Kit storage: -20°C

Necessary equipment: 7500 Real Time PCR System

Status: Ready to use

GNAS-COLD-MAMAPCR real time cod. BM-004​

 

Quantification assay of McCune-Albright syndrome (MAS)

 

·      GNAS-COLD-MAMAPCR real time Quantification complete kit 25 tests BM-004

 

The McCune-Albright syndrome (MAS) is a potentially severe disorder hallmarked by fibrous bone dysplasia, café-au-lait skin spots, and endocrine hyperfunction. It is caused by postzygotic activating mutations at the R201 codon of the GNAS gene, leading to a state of somatic mosaicism. Our aim was to improve the mutation detection rate and to quantify the presence of R201 GNAS mutations in different DNA samples from MAS patients8.

We developed a novel real-time COLD-MAMA-PCR TaqMan-based method that can quantify low frequencies of GNAS mutations. A linear correlation between the true and the measured relative frequency of mutations (real-time COLD-MAMA-PCR-measured relative mutation frequency [RMF], defined as the proportion of sequence reads containing the mutation) was observed until 2.5%, indicating a reliable quantification with R201H and R201C (R2 = 0.984 and 0.987, respectively). The actual sensitivity of the assay was determined by the lowest standard dilution consistently detectable in replicate reactions at a frequency of 100%, and it was found to be 0.05% for both mutations. Considering the linear portion of the standard curves, the real-time COLD-MAMA-PCR assay is unable to distinguish differences in the percentage of mutant alleles when present between 0.05 and 2.5% as well as above 40%. Thus, results are reported as <2.5% mutant alleles (<5% mutant cells) or >40% mutant alleles (>80% mutant cells). Samples with mutant allele percentages between 0.5 and 2.5% are referred to as “weakly positive,” while samples with mutant allele percentages between 0.5 and 0.05% are referred to as “doubtful.” User friendly and complete, the GNAS-COLD-MAMAPCR real time Quantification kit is suitable for any laboratory.

 

Reference

1.      de Sanctis L, Galliano I, Montanari P, Matarazzo P, Tessaris D, Bergallo M. Combining Real-Time COLD- and MAMA-PCR TaqMan Techniques to Detect and Quantify R201 GNAS Mutations in the McCune-Albright Syndrome. Horm Res Paediatr. 2017;87(5):342-349. doi: 10.1159/000463384.