CMT 1A: Quantitative Fluorescence-Polymerase Chain Reaction Assay for the Detect

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Genet Test Mol Biomarkers. 2010 Feb 28

Quantitative Fluorescence-Polymerase Chain Reaction Assay for the Detection of

the Duplication of the Charcot Marie Tooth Disease Type 1A Critical Region.

De Toffol S, Bellone E, Dulcetti F, Ruggeri AM, Maggio PP, Pulimeno MR, Mandich

P, Maggi F, Simoni G, Grati FR.

1 Unit of Research and Development , Cytogenetics, and Molecular Biology, TOMA

Advanced Biomedical Assays S.p.A., Busto Arsizio, Varese, Italy .

Charcot Marie Tooth (CMT) syndrome is the most common hereditary peripheral

neuropathy, with an incidence of about 1 in 2500. The subtype 1A (CMT1A) is

caused by a tandem duplication of a 1.5-Mb region encompassing the PMP22 gene.

Conventional short tandem repeat (STR) analysis can reveal this unbalance if a

triallelic pattern, defining with certainty the presence of duplication, is

present.

In case of duplication with a biallelic pattern, it can only indicate a

semiquantitative dosage of the fluorescence intensity ratio of the two

fragments.

In this study we developed a quantitative fluorescence-PCR using seven highly

informative STRs within the CMT1A critical region that successfully disclosed or

excluded the presence of the pathogenic unbalance in a cohort of 60 samples

including 40 DNAs from samples with the CMT1A duplication previously

characterized with two different molecular approaches, and 20 diagnostic samples

from 10 members of a five-generation pedigree segregating CMT1A, 8 unrelated

cases and 2 prenatal samples.

The application of the quantitative fluorescence-PCR using STRs located in the

critical region could be a reliable method to evaluate the presence of the PMP22

duplication for the diagnosis and classification of hereditary neuropathies in

asymptomatic subjects with a family history of inherited neuropathy, in prenatal

samples in cases with one affected parent, and in unrelated patients with a

sporadic demyelinating neuropathy with clinical features resembling CMT (i.e.,

pes cavus with hammer toes) or with conduction velocities in the range of CMT1A.