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Peripheral Neuropathies via the HINT1 Gene

  • Summary and Pricing
  • Clinical Features and Genetics
  • Citations
  • Methods
  • Ordering/Specimens
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TEST METHODS

Sequencing

Test Code Test Copy GenesIndividual Gene PriceCPT Code Copy CPT Codes
2141 HINT1$490.00 81479 Add to Order
Targeted Testing

For ordering targeted known variants, please proceed to our Targeted Variants landing page.

Turnaround Time

The great majority of tests are completed within 18 days.

Clinical Sensitivity

In the original study describing HINT1 as a causative gene for inherited neuropathies, a large cohort study of individuals suspected of autosomal recessive inherited peripheral neuropathy was performed (Zimon et al. 2012). Thirty-one of 293 (11%) cases were found to have HINT1 pathogenic variants. In 31 patients specifically with axonal neuropathy and neuromyotonia, 21 (68%) were found to have HINT1 pathogenic variants. In an additional study using exome sequencing on patients with a clinical diagnosis of distal hereditary motor neuropathy, two of 12 were found to have HINT1 variants (Zhao et al. 2014). In another large cohort study of Czech patients with either motor neuropathy or motor and sensory neuropathy, 14 of 196 (7%) individuals had pathogenic HINT1 variants (Laššuthová et al. 2015). The estimated carrier frequency in Czech populations for the pathogenic Arg37Pro variant is estimated to be ~1:182.    Analytical sensitivity should be almost 100% because all reported pathogenic variants are detectable by sequencing.

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Deletion/Duplication Testing via aCGH

Test Code Test Copy GenesIndividual Gene PriceCPT Code Copy CPT Codes
600 HINT1$690.00 81479 Add to Order
Pricing Comment

# of Genes Ordered

Total Price

1

$690

2

$730

3

$770

4-10

$840

11-30

$1,290

31-100

$1,670

Over 100

Call for quote

Turnaround Time

The great majority of tests are completed within 28 days.

Clinical Features

Pathogenic variants in the HINT1 gene cause inherited peripheral neuropathies that range from a strict distal motor neuropathy without sensory involvement to axonal neuropathy with neuromyotonia and mild sensory involvement (Zimon et al. 2012; Zhao et al. 2014). Therefore, some patients are clinically diagnosed as having Charcot Marie Tooth 2 whereas others are diagnosed with distal hereditary motor neuropathy. One defining clinical feature seen in many patients is neuromyotonia. In two different cohort studies around 70% of affected individuals had action myotonia in the hands and/or neuromyotonic discharges on needle EMG (Zimon et al. 2012; Laššuthová et al. 2015). Disease onset is typically in the first or second decade and most patients present with distal weakness in the lower and upper limbs; however, only lower limb involvement has also been observed. There is a predominance of more motor neuron involvement than sensory nerves being affected.

Genetics

HINT1 peripheral neuropathies are inherited in an autosomal recessive manner. The HINT1 gene consists of 3 coding exons and encodes the 126 amino acid histidine triad nucleotide binding protein 1 (HINT1). HINT1 is a ubiquitously expressed homodimeric purine phosphoramidase and also acts as a tumor suppressor that functions in several apoptotic pathways (Zimon et al. 2012). Many of the pathogenic variants lie near the catalytic core and alter substrate binding, protein stability, or catalytic activity. Several of the described missense variants lie in the catalytic active site and abolish enzyme activity (Zimon et al. 2012). Reported pathogenic variants include missense and nonsense variants (Zimon et al. 2012, Zhao et al. 2014, Laššuthová et al. 2015). HINT1 is the fifth most frequent cause of CMT2/HMN in Czech populations with the p.Arg37Pro variant being the most common pathogenic variant in this population (Laššuthová et al. 2015). Carrier frequency of the P.Arg37Pro variant in Czech populations is estimated to be ~1:180 (Laššuthová et al. 2015).

Testing Strategy

Testing involves PCR amplification from genomic DNA and Sanger sequencing of all coding exons in the HINT1 gene and ~20bp of adjacent noncoding sequences. This testing strategy will reveal coding sequence changes, splice site mutations and small insertions or deletions in the HINT1 gene, but will not detect large duplications or deletions of the HINT1 locus. We will also sequence any single exon (Test #100) or pair of exons (Test #200) in family members of patients with known mutations or to confirm research results.

Indications for Test

Individuals with clinical symptoms of axonal neuropathy and neuromyotonia or distal hereditary motor neuropathy.

Gene

Official Gene Symbol OMIM ID
HINT1 601314
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

CONTACTS

Genetic Counselors
Geneticist
Citations
  • Laššuthová P, Brozková DŠ, Krutová M, Neupauerová J, Haberlová J, Mazanec R, Dvorácková N, Goldenberg Z, Seeman P. 2015. Mutations in HINT1 are one of the most frequent causes of hereditary neuropathy among Czech patients and neuromyotonia is rather an underdiagnosed symptom. Neurogenetics 16: 43–54. PubMed ID: 25342199
  • Zhao H, Race V, Matthijs G, Jonghe P De, Robberecht W, Lambrechts D, Damme P Van. 2014. Exome sequencing reveals HINT1 mutations as a cause of distal hereditary motor neuropathy. Eur. J. Hum. Genet. 22: 847–850. PubMed ID: 24105373
  • Zimon M, Baets J, Almeida-Souza L, Vriendt E De, Nikodinovic J, Parman Y, Battaloglu E, Matur Z, Guergueltcheva V, Tournev I, Auer-Grumbach M, Rijk P De, Petersen BS, Müller T, Fransen E, Van Damme P, Löscher WN, Barisic N, Mitrovic Z, Previtali SC, Topaloglu H, Bernert G, Beleza-Meireles A, Todorovic S, Savic-Pavicevic D, Ishpekova B, Lechner S, Peeters K, Ooms T, Hahn AF, Züchner S, Timmerman V, Van Dijck P, Rasic VM, Janecke AR, De Jonghe P, Jordanova A. 2012. Loss-of-function mutations in HINT1 cause axonal neuropathy with neuromyotonia. Nature Genetics 44: 1080–1083. PubMed ID: 22961002
Order Kits
TEST METHODS

Bi-Directional Sanger Sequencing

Test Procedure

Nomenclature for sequence variants was from the Human Genome Variation Society (http://www.hgvs.org).  As required, DNA is extracted from the patient specimen.  PCR is used to amplify the indicated exons plus additional flanking non-coding sequence.  After cleaning of the PCR products, cycle sequencing is carried out using the ABI Big Dye Terminator v.3.0 kit.  Products are resolved by electrophoresis on an ABI 3730xl capillary sequencer.  In most cases, sequencing is performed in both forward and reverse directions; in some cases, sequencing is performed twice in either the forward or reverse directions.  In nearly all cases, the full coding region of each exon as well as 20 bases of non-coding DNA flanking the exon are sequenced.

Analytical Validity

As of March 2016, we compared 17.37 Mb of Sanger DNA sequence generated at PreventionGenetics to NextGen sequence generated in other labs. We detected only 4 errors in our Sanger sequences, and these were all due to allele dropout during PCR. For Proficiency Testing, both external and internal, in the 12 years of our lab operation we have Sanger sequenced roughly 8,800 PCR amplicons. Only one error has been identified, and this was due to sequence analysis error.

Our Sanger sequencing is capable of detecting virtually all nucleotide substitutions within the PCR amplicons. Similarly, we detect essentially all heterozygous or homozygous deletions within the amplicons. Homozygous deletions which overlap one or more PCR primer annealing sites are detectable as PCR failure. Heterozygous deletions which overlap one or more PCR primer annealing sites are usually not detected (see Analytical Limitations). All heterozygous insertions within the amplicons up to about 100 nucleotides in length appear to be detectable. Larger heterozygous insertions may not be detected. All homozygous insertions within the amplicons up to about 300 nucleotides in length appear to be detectable. Larger homozygous insertions may masquerade as homozygous deletions (PCR failure).

Analytical Limitations

In exons where our sequencing did not reveal any variation between the two alleles, we cannot be certain that we were able to PCR amplify both of the patient’s alleles. Occasionally, a patient may carry an allele which does not amplify, due for example to a deletion or a large insertion. In these cases, the report contains no information about the second allele.

Similarly, our sequencing tests have almost no power to detect duplications, triplications, etc. of the gene sequences.

In most cases, only the indicated exons and roughly 20 bp of flanking non-coding sequence on each side are analyzed. Test reports contain little or no information about other portions of the gene, including many regulatory regions.

In nearly all cases, we are unable to determine the phase of sequence variants. In particular, when we find two likely causative mutations for recessive disorders, we cannot be certain that the mutations are on different alleles.

Our ability to detect minor sequence variants, due for example to somatic mosaicism is limited. Sequence variants that are present in less than 50% of the patient’s nucleated cells may not be detected.

Runs of mononucleotide repeats (eg (A)n or (T)n) with n >8 in the reference sequence are generally not analyzed because of strand slippage during PCR and cycle sequencing.

Unless otherwise indicated, the sequence data that we report are based on DNA isolated from a specific tissue (usually leukocytes). Test reports contain no information about gene sequences in other tissues.

Deletion/Duplication Testing Via Array Comparative Genomic Hybridization

Test Procedure

Equal amounts of genomic DNA from the patient and a gender matched reference sample are amplified and labeled with Cy3 and Cy5 dyes, respectively. To prevent any sample cross contamination, a unique sample tracking control is added into each patient sample. Each labeled patient product is then purified, quantified, and combined with the same amount of reference product. The combined sample is loaded onto the designed array and hybridized for at least 22-42 hours at 65°C. Arrays are then washed and scanned immediately with 2.5 µM resolution. Only data for the gene(s) of interest for each patient are extracted and analyzed.

Analytical Validity

PreventionGenetics' high density gene-centric custom designed aCGH enables the detection of relatively small deletions and duplications within a single exon of a given gene or deletions and duplications encompassing the entire gene. PreventionGenetics has established and verified this test's accuracy and precision.

Analytical Limitations

Our dense probe coverage may allow detection of deletions/duplications down to 100 bp; however due to limitations and probe spacing this cannot be guaranteed across all exons of all genes. Therefore, some copy number changes smaller than 100-300 bp within a targeted large exon may not be detected by our array.

This array may not detect deletions and duplications present at low levels of mosaicism or those present in genes that have pseudogene copies or repeats elsewhere in the genome.

aCGH will not detect balanced translocations, inversions, or point mutations that may be responsible for the clinical phenotype.

Breakpoints, if occurring outside the targeted gene, may be hard to define.

The sensitivity of this assay may be reduced when DNA is extracted by an outside laboratory.

Order Kits

Ordering Options


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.
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.

SPECIMEN TYPES
WHOLE BLOOD

(Delivery accepted Monday - Saturday)

  • Collect 3 ml -5 ml (5 ml preferred) of whole blood in EDTA (purple top tube) or ACD (yellow top tube). For Test #500-DNA Banking only, collect 10 ml -20 ml of whole blood.
  • For small babies, we require a minimum of 1 ml of blood.
  • Only one blood tube is required for multiple tests.
  • Ship blood tubes at room temperature in an insulated container. Do not freeze blood.
  • During hot weather, include a frozen ice pack in the shipping container. Place a paper towel or other thin material between the ice pack and the blood tube.
  • In cold weather, include an unfrozen ice pack in the shipping container as insulation.
  • At room temperature, blood specimen is stable for up to 48 hours.
  • If refrigerated, blood specimen is stable for up to one week.
  • Label the tube with the patient name, date of birth and/or ID number.

DNA

(Delivery accepted Monday - Saturday)

  • Send in screw cap tube at least 5 µg -10 µg of purified DNA at a concentration of at least 20 µg/ml for NGS and Sanger tests and at least 5 µg of purified DNA at a concentration of at least 100 µg/ml for gene-centric aCGH, MLPA, and CMA tests, minimum 2 µg for limited specimens.
  • For requests requiring more than one test, send an additional 5 µg DNA per test ordered when possible.
  • DNA may be shipped at room temperature.
  • Label the tube with the composition of the solute, DNA concentration as well as the patient’s name, date of birth, and/or ID number.
  • We only accept genomic DNA for testing. We do NOT accept products of whole genome amplification reactions or other amplification reactions.

CELL CULTURE

(Delivery preferred Monday - Thursday)

  • PreventionGenetics should be notified in advance of arrival of a cell culture.
  • Culture and send at least two T25 flasks of confluent cells.
  • Some panels may require additional flasks (dependent on size of genes, amount of Sanger sequencing required, etc.). Multiple test requests may also require additional flasks. Please contact us for details.
  • Send specimens in insulated, shatterproof container overnight.
  • Cell cultures may be shipped at room temperature or refrigerated.
  • Label the flasks with the patient name, date of birth, and/or ID number.
  • We strongly recommend maintaining a local back-up culture. We do not culture cells.
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