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Schwannomatosis

Schwannomatosis is a form of neurofibromatosis that causes growth of benign tumors, called schwannomas, along the spinal and peripheral nerves. Genetic testing for SMARCB1 can help confirm a diagnosis of schwannomatosis, which can lead to better management.

Schwannomatosis is a form of neurofibromatosis that causes growth of benign tumors, called schwannomas, along the spinal and peripheral nerves. Genetic testing for SMARCB1 can help confirm a diagnosis of schwannomatosis, which can lead to better management.

SMARCB1 is evaluated by next generation sequencing (NGS) or Sanger sequencing of all coding domains, and well into the flanking 5’ and 3’ ends of all the introns and untranslated regions. Clinically significant intronic findings beyond 5 base pairs are always reported. Intronic variants of unknown or unlikely clinical significance are not reported beyond 5 base pairs from the splice junction. Additional Sanger sequencing is performed for any regions missing or with insufficient read depth coverage for reliable heterozygous variant detection. Potentially homozygous variants, variants in regions complicated by pseudogene interference, and variant calls not satisfying depth of coverage and variant allele frequency quality thresholds are verified by Sanger sequencing. Gross deletion/duplication analysis is performed for the covered exons and untranslated regions of SMARCB1 using read-depth from NGS data with confirmatory multiplex ligation-dependent probe amplification (MLPA) and/or targeted chromosomal microarray. 

Genes analyzed
Code
Test Name
Turnaround
Genes
7180
Schwannomatosis
5-14 days
1 Gene
Schwannomatosis
1 Gene
SMARCB1
Test Requisition Form
Neurology
Mutation Detection Rate
>99.9%
Schwannomatosis
can detect the described mutations in SMARCB1, when present (analytic sensitivity).*

Test Description

SMARCB1 is evaluated by next generation sequencing (NGS) or Sanger sequencing of all coding domains, and well into the flanking 5’ and 3’ ends of all the introns and untranslated regions. Clinically significant intronic findings beyond 5 base pairs are always reported. Intronic variants of unknown or unlikely clinical significance are not reported beyond 5 base pairs from the splice junction. Additional Sanger sequencing is performed for any regions missing or with insufficient read depth coverage for reliable heterozygous variant detection. Potentially homozygous variants, variants in regions complicated by pseudogene interference, and variant calls not satisfying depth of coverage and variant allele frequency quality thresholds are verified by Sanger sequencing. Gross deletion/duplication analysis is performed for the covered exons and untranslated regions of SMARCB1 using read-depth from NGS data with confirmatory multiplex ligation-dependent probe amplification (MLPA) and/or targeted chromosomal microarray.