Legius Syndrome

Known Mutation Testing (KT2)                                                    

DESCRIPTION

Mendelian Inheritance in Man number: 611431

Recently, a new autosomal dominant condition resembling NF1 was described, consisting of mainly multiple CAL-spots, freckling and relative macrocephaly (Brems et al, 2007). Some patients also have learning disabilities or hyperactivity. In none of the adult patients identified so far, neurofibromas or central nervous system tumors were observed Brems et al, 2007; Pasmant et al, 2009; Spurlock et al, 2009; Messiaen et al, 2009; Denayer et al, 2011. In addition, no Lisch nodules, optic pathway gliomas or NF1-associated osseous lesions have been found. A Noonan-like dysmorphology was observed in some individuals. The disorder is caused by germline loss-of-function mutations in SPRED1. ~50% of the individuals carrying a SPRED1 mutation fulfill the NIH diagnostic criteria for NF1, based on the pigmentary symptoms. So far, only SPRED1 point mutations had been identified as the cause of this syndrome. Using Multiplex Ligation-dependent Probe Amplification (MLPA) assay covering all SPRED1 exons and quantitative PCR in a cohort of 510 NF1-negative patients presenting with multiple CALMs with or without freckling, but no other NF1 diagnostic signs, 4 different deletions were identified (Spencer et al, AJMG In Press). Deletions account for ~10% of SPRED1 mutations in this cohort. These results indicate the need for dosage analysis to complement sequencing-based SPRED1 mutation analyses.

In individuals with CALMs with or without freckling and no other specific distinguishing features, the NIH criteria cannot reliably distinguish NF1 from Legius syndrome. In such patients, a correct diagnosis has important implications for prognosis, counseling, and potential prenatal genetic diagnosis.  Based on a cross-sectional study we estimate that patients presenting sporadically with these pigmentary signs only will carry a mutation in the NF1 gene in ~43% of cases and in the SPRED1 gene in ~1.3% of cases (Messiaen et al, 2009). When such patients have a family history of CALMs with or without freckling and no additional NF1-related criteria, an NF1 mutation will be found in ~73% of cases and in the SPRED1 gene in ~19% of cases.

SPRED1 is a member of the SPROUTY/SPRED family of proteins that act as negative regulators of RAS-RAF interaction and mitogen-activated protein kinase (MAPK) signaling.


INDICATIONS FOR DIRECT TESTING

  • Relatives of patients with a known SPRED1 mutation


TESTING METHODOLOGY

We offer a targeted detection of a previously characterized SPRED1 mutation within the family. Depending on the mutation identified previously in the family, targeted testing involves direct sequencing of a specific region or copy number analysis by MLPA and quantitative PCR.

KT2 is provided free of charge to all relevant relatives of a proband in whom a novel missense alteration was found that needs further clarification to come to a final conclusion.  As the final conclusion on the pathogenicity of a missense alteration relies on accurate phenotypic data, the testing in relevant relatives is provided free of charge only if a phenotypic checklist is filled out by a healthcare professional that made the clinical assessment of the relatives.  The correct interpretation of the results also relies on the correct disclosure of the biological relationships. 
 

SPECIMEN REQUIREMENTS

We require 1 milliliter of whole blood. Blood samples must be collected in EDTA (purple topped) tubes. 


TRANSPORT

If specimen is from clinics within UAB or Kirklin Clinic, please call 934-7107 for pick-up. If specimens are being sent from some other location, please ship via UPS or Federal Express.

1. Be sure that the shipping air bill is marked “Priority”, either Domestic or International.
2. 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). You can use our collection kits, which we will send to physicians directly upon request.


TURN AROUND TIME

10 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

SPRED1 Test Requisition 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 SPRED1 will not be accepted for the following reasons:

  • No label (patient’s full name and date of collection) on the specimens
  • No referring physician’s or genetic counselor’s names and addresses
  • No billing information if this is a fee for service test
  • No informed consent
  • No phenotypic checklist: we offer free of charge targeted testing to all relevant relatives of a proband in whom a novel missense variant was identified. Testing of these relatives may allow us to make a final conclusion on the pathogenicity of the novel missense variant and allow us to provide better counseling now and in the future. Free of charge targeted testing will only be provided if the necessary phenotypic information on the proband and relatives filled out by a healthcare professional accompanies the samples. If no phenotypic information is provided, we will charge the institution for the test.

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

REFERENCES

Brems H, Chmara M, Sahbatou M, Denayer E, Taniguchi K, Kato R, Somers R, Messiaen L, De Schepper S, Fryns J-P, Cools J, Marynen P, Thomas G, Yoshimura A, Legius E – Germline loss-of function mutations in SPRED1 cause a neurofibromatosis 1-like phenotype. Nat Genet 39: 1120-1126, 2007. (pubmed)

Messiaen L, Yao S, Brems H, Callens T, Sathienkijkanchai A, Denayer E, Spencer E, Arn P, Babovic-Vuksanovic D, Bay C, Bobele G, Cohen BH, Escobar L, Eunpu D, Grebe T, Greenstein R, Hachen R, Irons M, Kronn D, Lemire E, Leppig K, Lim C, McDonald M, Narayanan V, Pearn A, Pedersen R, Powell B, Shapiro LR, Skidmore D, Tegay D, Thiese H, Zackai EH, Vijzelaar R, Taniguchi K, Ayada T, Okamoto F, Yoshimura A, Parret A, Korf B, Legius E- Clinical and Mutational Spectrum of Neurofibromatosis type 1-like syndrome.  JAMA 2009: 302(19): 2111-8 (pubmed)

Muram-Zborovski TM, Stevenson DA, Viskochil DH, Dries DC, Wilson AR, Mao R. 2010. SPRED1 Mutations in a Neurofibromatosis Clinic. J Child Neurol. (pubmed)

Pasmant E, Sabbagh A, Hanna N, Masliah-Planchon J, Jolly E, Goussard P, Ballerini P, Cartault F, Barbarot S, Landman-Parker J, Soufir N, Parfait B, Vidaud M, Wolkenstein P, Vidaud D. 2009. SPRED1 germline mutations caused a neurofibromatosis type 1 overlapping phenotype. J Med Genet. (pubmed)

Spurlock G, Bennett E, Chuzhanova N, Thomas N, Jim H, Side L, Davies S, Haan E, Kerr B, Huson SM, Upadhyaya M. 2009. SPRED1 mutations (Legius syndrome): another clinically useful genotype for dissecting the NF1 phenotype. J Med Genet.  (pubmed)

Spencer E, Davis J, Mikhail F, Fu C, Vijzelaar R, Zackai E, Feret H, Meyn  S, Shugar A, Bellus G, Kocsis K, Kivirikko S, Poyhonen M, Messiaen L.  Identification of SPRED1 Deletions using RT-PCR, Multiplex Ligation-dependent Probe Amplification and Quantitative PCR. American Journal of Medical Genetics. In Press