Blueprint Genetics launches new genetic diagnostic tests for Becker and Duchenne muscular dystrophies and an updated panel for Emery-Dreifuss muscular dystrophy with the addition of titin (TTN) gene. In line with our other diagnostic panels, we target the sequencing to all protein coding exons, exon-intron boundaries and other regions with reported disease related variants.
Becker and Duchenne Muscular Dystrophy Test:
In January 2014, Wei and colleagues introduced an effective single-step NGS test for Duchenne and Becker muscular dystrophy (DMD & BDM), which has a potential to replace old-fashioned step-wise testing strategy with MLPA followed by sequencing (Wei et al., Eur J Hum Genet 2014). Their study consisted of 89 DMD/BDM patients, 18 female carriers and 245 controls, and showed 99.99% specificity and 98.96% sensitivity for copy number variations detection (CNV) and 100% accuracy for the identification of single-nucleotide variation mutations. NGS based assay had higher accuracy and better insight into comprehensive genetic information as it detected also partial deletions/duplications.
Blueprint Genetics is turning these research achievements into clinical practice. BpG Becker and Duchenne Muscular Dystrophy Test (DMD Test) relies on initial NGS testing followed by direct Sanger sequencing of variations when applicable. Current Panel, version 1.0, covers all known point mutations and insertions and deletions up to 50 bp. It is recommended for patient’s who is tested negative by deletion-duplication analysis. Excitingly, we are now validating our in-house built CNV tool that is designed to have similar diagnostic ability as demonstrated in Wei’s study. Meticulous clinical validation of the CNV tool is essential to confirm high quality and maximal diagnostic performance. Therefore, our customers will get this benefit in version 2.0 of the test. Please see more information at http://blueprintgenetics.com/becker-and-duchenne-muscular-dystrophies/. Our Panel version 2.0 will be launched soon.
Emery-Dreifuss Muscular Dystrophy Panel update:
BpG EDMD Panel version 1.0 covers LMNA, EMD, SYNE1, SYNE2, FHL1 and TMEM43 genes. Addition of titin (TTN) gene into our updated EDMD Panel guarantees maximal diagnostic performance whenever clinical presentation is suggestive for EDMD. Of note, only a few laboratories worldwide provide diagnostic grade sequencing for entire TTN gene.
Here we explain shortly the justification for adding TTN into the panel. Heterozygous and especially homozygous TTN mutations are linked to neuromuscular diseases such as 1) early-onset myopathy with fatal cardiomyopathy (OMIM #611705) and 2) limb-girdle type 2J muscular dystrophy (OMIM #608807). However, the pathophysiological role of titin in skeletal muscle conditions and cardiomyopathies is incompletely understood, due to limited number of studies where titin gene has been fully sequenced in respective patients groups. In 2014, Chauveau and colleagues published a study of 23 families with congenital core myopathy (main non-dystrophic myopathy in childhood) and primary heart disease using partial TTN sequencing followed by functional studies (Chauveau et al. 2014). They identified recessive TTN mutations (homozygous and compound heterozygous) in 17% of the patients. In their study, phenotype analysis identified four novel titinopathies including cardiac septal defects, left ventricular non-compaction, Emery-Dreifuss muscular dystrophy and arthrogryposis. Parents with a single heterozygous mutation were healthy. Based on this novel finding, BpG has added the TTN gene into our EDMD Panel, even though the role of TTN in EDMD needs still further confirmation. We believe that evaluation of all coding exons of the TTN gene can help differential diagnostics in patients with early onset non-dystrophic myopathy. Please see more information at http://blueprintgenetics.com/blueprint-genetics-edmd-panel/.
These March additions into our test menu will widen the spectrum of genetic tests. Excitingly, we are also in the process of developing genetic tests for other neuromuscular and retinal diseases. All our panels are developed in close collaboration with clinical specialists in the respected fields of medicine.
To order these tests visit our website (www.blueprintgenetics.com) or login at Nucleus (nucleus.blueprintgenetics.com).
Blueprint Genetics Team