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Brown-Vialetto-van Laere Syndrome and Fazio-Londe Disease Panel

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy Genes Gene CPT Codes Copy CPT Codes
SLC52A2 81479,81479
SLC52A3 81479,81479
Test Code Test Copy Genes Panel CPT Code Gene CPT Codes Copy CPT Code Base Price
12087Genes x (2)81479 81479(x4) $990 Order Options and Pricing

Pricing Comments

We are happy to accommodate requests for testing single genes in this panel or a subset of these genes. The price will remain the list price. If desired, free reflex testing to remaining genes on panel is available. Alternatively, a single gene or subset of genes can also be ordered via our Custom Panel tool.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).

Turnaround Time

3 weeks on average for standard orders or 2 weeks on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.


Genetic Counselors


  • Li Fan, MD, PhD, FCCMG, FACMG

Clinical Features and Genetics

Clinical Features

Brown-Vialetto-van Laere syndrome 1 and 2 are rare neurologic disorders with a phenotypic spectrum of motor, sensory, and cranial nerve neuropathy. The major symptoms include bulbar palsy, neurological deterioration, muscle weakness, optic atrophy, respiratory insufficiency, and early death. Onset of symptoms has been reported in the first decade of life (Manole et al. 2017. PubMed ID: 29053833; Green et al. 2010. PubMed ID: 20206331). Sensorineural deafness was also found to be a common feature, but more often in patients with later onset. High-dose oral riboflavin supplementation therapy has been shown to decrease symptoms (Foley et al. 2014. PubMed ID: 24253200).

Fazio-Londe disease is a progressive bulbar palsy with onset in childhood that presents with hypotonia and respiratory insufficiency due to diaphragmatic paralysis (Bosch et al. 2011. PubMed ID: 21110228).

Brown-Vialetto-van Laere syndrome and Fazio-Londe disease are believed to represent variable presentations of a single disorder (Dipti et al. 2005. PubMed ID: 16122634).


Brown-Vialetto-van Laere syndrome 1 and 2, and Fazio-Londe disease, are inherited as autosomal recessive disorders. Pathogenic variants in SLC52A3 and SLC52A2 cause Brown-Vialetto-van Laere syndrome 1 and 2 as well as Fazio-Londe disease (Johnson et al. 2010. PubMed ID: 20920669; Green et al. 2010. PubMed ID: 20206331; Haack et al. 2012. PubMed ID: 22864630; Johnson et al. 2012. PubMed ID: 22740598).

The SLC52A3 gene encodes solute carrier family 52 member 3 which is a riboflavin transporter (Green et al. 2010. PubMed ID: 20206331; Bosch et al. 2011. PubMed ID: 21110228). SLC52A3 pathogenic variants reported include missense, nonsense, splicing, and small frameshift deletions and duplications. No large deletions and duplications have been reported (Human Gene Mutation Database).

The SLC52A2 gene encodes solute carrier family 52, member 2 which is also a riboflavin transporter (Yonezawa and Inui. 2013. PubMed ID: 23506902). SLC52A2 pathogenic variants include missense, nonsense, splicing and small frameshift deletions. No large deletions and duplications have been reported (HGMD).

Functional studies have shown that pathogenic variants in SLC52A3 and SLC52A2 result in reduced riboflavin transporter expression, and therefore, decreased uptake of riboflavin. As riboflavin metabolites are critical components of the mitochondrial electron transport chain, mitochondrial dysfunction is a downstream consequence of the riboflavin transporter gene defects (Haack et al. 2012. PubMed ID: 22864630; Foley et al. 2014. PubMed ID: 24253200; Manole et al. 2017. PubMed ID: 29053833).

Clinical Sensitivity - Sequencing with CNV PGxome

Brown-Vialetto-van Laere syndrome and Fazio-Londe disease are both rare disorders, and clinical sensitivity cannot yet be estimated. Analytical sensitivity should be high because all pathogenic variants thus far reported are expected to be detected by sequencing genomic DNA.

Testing Strategy

This test is performed using Next-Gen sequencing with additional Sanger sequencing as necessary.

This panel provides 100% coverage of all coding exons of the genes plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define coverage as ≥20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).

Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).

Indications for Test

Patients with clinical features consistent with Brown-Vialetto-van Laere syndrome 1 and 2, as well as Fazio-Londe disease.


Official Gene Symbol OMIM ID
SLC52A2 607882
SLC52A3 613350
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Related Test




Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page

If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.

Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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2) Select Additional Test Options

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Note: acceptable specimen types are whole blood and DNA from whole blood only.
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