NEUROFIBROMATOSIS Type 1

Comprehensive Testing in Affected Tissues (NF14C/NF14N)                                

DESCRIPTION

Online Mendelian Inheritance in Man number: 162200

Click here for Gene Reviews Clinical Summary.

Neurofibromatosis type 1 is a completely penetrant, autosomal dominant disorder with a frequency of 1/3500 births in all ethnic populations. NF1 is a progressive disorder, characterized by multiple café-au-lait spots, neurofibromas, and Lisch nodules, although additional features may develop. NF1 is notorious for its variable expression. About 50% of cases are due to new dominant mutations, where neither parent has signs of the disorder. An affected individual has a 50% risk of transmitting NF1 to each offspring, although the degree of severity can differ from person to person, even within the same family. 

Segmental patients may only have NF1 symptoms over a defined area of their body, and the symptoms may be due to a postzygotic mutation, creating a mosaic individual. 

In patients with mild non-localized NF1 symptoms, disease can also be due to a postzygotic mutation, present in the affected tissues, but not in the blood lymphocytes (Maertens et al, 2007).  Comprehensive testing in affected tissues can confirm somatic mosaicism for NF1.


INDICATIONS FOR DIRECT TESTING

  • Individuals suspected to have segmental NF1 and in whom no mutation was found in the blood lymphocytes by comprehensive NF1 mutation analysis
  • Sporadic patients who have symptoms of NF1 but in whom no NF1 mutation was identified in the blood lymphocytes. Mosaic NF1 can be diagnosed starting from biopsies from either CAL-spots or neurofibromas.


TESTING METHODOLOGY

We offer a comprehensive test in cultured cells from the affected region (Schwann cells or melanocytes) resulting in the full characterization of the NF1 mutation at the genomic DNA level (Maertens et al, 2007, De Schepper et al, 2007). The complete NF1 coding region is analyzed by a cascade of complementary mutation detection techniques, enabling us to identify the mutation in ~95% of non-founder patients fulfilling the NIH diagnostic criteria [Messiaen et al 2000, Messiaen and Wimmer 2005, Wimmer et al 2007, Messiaen and Wimmer, 2008].  Mutations screened for include truncating mutations (nonsense, frameshift, splicing mutations including deep-intronic splice mutations), missense mutations, multi-exon deletions and total gene deletions. We always fully characterize the mutation at the genomic DNA level.
 

SPECIMEN REQUIREMENTS

Segmental testing requires analysis of an affected region.  Either a skin biopsy of a café-au-lait spot or fresh tumor tissue can be used to perform the comprehensive testing. Please contact us at medgenomics@uabmc.edu or 205-934-5562 to set up a time prior to taking biopsy/biopsies in your patient, so we can provide individualized advice and ship out appropriate collection/transport media and forms prior to surgery.

Testing from café-au-lait spots (NF14C):

Comprehensive NF1 testing from café-au-lait spots requires selective culturing of melanocytes from a skin biopsy.  We require 2-3 3mm punch biopsies for testing.  Biopsies must be collected in special transport media that will be shipped to your facility prior to surgery.  Please allow 2-3 days for delivery. The viability of melanocytes quickly declines 24 hours after the biopsy is removed.

Please include buccal swab samples from the patient.  Instructions and sterile swabs will be included with the biopsy collection kit.  For patients whose blood has never been tested, please also submit 10 milliliters of whole blood collected in EDTA (purple top) tubes.

Instructions for collecting and shipping skin biopsies (CAL-spots) for NF1 testing

Testing from fresh neurofibroma tissue (NF14N):

Comprehensive NF1 testing from a tumor specimen requires selective culturing of the Schwann cells. We require a minimum of 2 biopsies of separate fresh neurofibromas (size of an eraserhead), collected in special transport media that will be shipped to your facility prior to surgery.  Please allow 2-3 days for delivery.

Please include buccal swab samples from the patient.  Instructions and sterile swabs will be included with the biopsy collection kit.  For patients whose blood has never been tested, please also submit 10 milliliters of whole blood collected in EDTA (purple top) tubes.

 Instructions for collecting and shipping neurofibromas for NF1 testing


TRANSPORT

Specimens for segmental NF1 testing must be shipped in the appropriate transport media.  Please contact our lab at 205-934-5562 in order to obtain the transport media and shipping instructions.  Please allow 2-3 days for delivery.  Specimens must be immediately placed in the transport media, and then sealed and shipped to our lab via overnight delivery service or international priority service.

If specimen is from clinics within UAB or Kirklin Clinic, please call 934-5562 for pick-up. If specimens are being sent from some other location, please ship via UPS or Federal Express.

1. DO NOT ship on ice.

2. Be sure that the shipping air bill is marked “Priority”, either Domestic or International.

3. Specimens must be packaged to prevent breakage and absorbent material must be included in the package to absorb liquids in the event that breakage occurs. Also, the package must be shipped in double watertight containers (e.g. a specimen pouch + the shipping companies Diagnostic Envelope).

4. Always contact us (Email –medgenomics@uab.edu, Phone – 205-934-5562) prior to sample shipment and provide us with the date of shipment and the tracking number of the package, so that we can better ensure receipt of the samples.


TURN AROUND TIME

Turn-around time is dependent on the size and quality of the tissue specimen we receive and the time it takes until sufficient cultured melanocytes or Schwann cells are obtained, however the following general turn-around times can be estimated:

Testing from skin biopsies and neurofibromas: 6 months (138 working days)


CPT CODES AND PRICES

Please find the most up to date prices and CPT codes for our testing services under the "Prices" tab of this website.


REQUIRED FORMS

NF1 Test Requisition-Seqmental NF1 including the phenotypic data form

Form for customs (International shipment)

Note: Detailed and accurate completion of this document is necessary for reporting purposes. The Medical Genomics Laboratory issues its clinical reports based on the demographic data provided by the referring institution on the lab requisition form. It is the responsibility of the referring institution to provide accurate information. If an amended report is necessary due to inaccurate or illegible documentation, additional reports will be drafted with charge.

Requests for Molecular Genetic testing for NF1 will not be accepted for the following reasons:

  • No label (patients full name and date of collection) on the specimens
  • No referring physician’s or genetic counselor’s names and addresses
  • No billing information
  • No informed consent
  • No phenotypic checklist

For more information, test requisition forms, or sample collection and mailing kits, please call: 205-934-5562.
 

REFERENCES

De Schepper S, Maertens O, Callens T, Naeyaert JM, Lambert J, Messiaen L. (2008) Somatic mutation analysis in NF1 café au lait spots reveals two NF1 hits in the melanocytes. J Invest Dermat,128(4): 1050-3 (pubmed)

Gutmann DH, Aylsworth A, Carey JC, Korf B, Marks J, Pyeritz RE, Rubenstein A, Viskochil D. (1997) The diagnostic evaluation and multidisciplinary management of neurofibromatosis 1 and neurofibromatosis 2. JAMA. Jul 2; 278(1): 51-7. Review. (pubmed)

Huson, SM; Hughes, RAC: The Neurofibromatoses: a Pathogenetic and Clinical Overview. London: Chapman & Hall Medical, 1994. (pubmed)

Maertens O, De Schepper S, Vandesompele J, Brems H, Heyns I, Janssens S, Speleman F, Legius E, Messiaen L (2007) Molecular dissection of isolated disease features in mosaic neurofibromatosis type 1. Am J Hum Genet 81(2):243-251. (pubmed)

Messiaen LM, Callens T, Mortier G, Beysen D, Vandenbroucke I, Van Roy N, Speleman F, De Paepe A (2000) Exhaustive mutation analysis of the NF1 gene allows identification of 95% of mutations and reveals a high frequency of unusual splicing defects. Hum Mutat.15(6):541-55. (pubmed)

Messiaen L and Wimmer K (2005) Pitfalls of automated comparative sequence analysis as a single platform for routine clinical testing for NF1. J. Med. Genet. 42(5): e25. (pubmed)

Messiaen LM and Wimmer K (2008) NF1 Mutational Spectrum, in Kaufmann D (ed): Neurofibromatoses. Monogr Hum Genet. Basel, Karger, Vol 16:63-77 (pubmed)

Upadhyaya M, Huson SM, Davies M, Thomas N, Chuzhanova N, Giovannini S, Evans DG, Howard E, Kerr B, Griffiths S, Consoli C, Side L, Adams D, Pierpont M, Hachen R, Barnicoat A, Li H, Wallace P, Van Biervliet JP, Stevenson D, Viskochil D, Baralle D, Haan E, Riccardi V, Turnpenny P, Lazaro C, Messiaen L (2007) An absence of cutaneous neurofibromas associated with a 3-bp inframe deletion in exon 17 of the NF1 gene (c.2970-2972 delAAT): evidence of a clinically significant NF1 genotype-phenotype correlation. Am J Hum Genet 80(1):140-51. (pubmed)

Wimmer K,  Roca X, Beiglbock H, Callens T, Etzler J, Rao A, Krainer A, Fonatsch C, Messiaen L (2007) Extensive in silico analysis of NF1 splicing defects uncovers determinants for splicing outcome upon 5’ splice-site disruption. Hum Mutat. 28(6): 599-612. (pubmed)