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Test ID MCP2Z MECP2 Gene, Full Gene Analysis, Varies


Ordering Guidance


Targeted testing (also called site-specific or known variant testing) is available for variants identified in this gene. See FMTT / Familial Mutation, Targeted Testing, Varies. To obtain more information about this testing option, call 800-533-1710.

 

If the reason for testing indicates the RET gene or multiple endocrine neoplasia type 2 syndrome (MEN2), order RETZZ / Multiple Endocrine Neoplasia Type 2 Syndrome, RET, Full Gene Analysis, Varies. If this test is ordered in this situation, it will be canceled and RETZZ ordered and performed as the appropriate test.



Shipping Instructions


Specimen preferred to arrive within 96 hours of collection.



Specimen Required


Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

 

Submit only 1 of the following specimens:

 

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.

Specimen Stability Information: Ambient (preferred)/Refrigerated

 

Specimen Type: Skin biopsy

Supplies: Fibroblast Biopsy Transport Media (T115)

Container/Tube: Sterile container with any standard cell culture media (eg, minimal essential media, RPMI 1640). The solution should be supplemented with 1% penicillin and streptomycin.

Specimen Volume: 4-mm punch

Specimen Stability Information: Refrigerated (preferred)/Ambient

Additional Information: A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.

 

Specimen Type: Cultured fibroblast

Container/Tube: T-25 flask

Specimen Volume: 2 flasks

Collection Instructions: Submit confluent cultured fibroblast cells from a skin biopsy from another laboratory. Cultured cells from a prenatal specimen will not be accepted.

Specimen Stability Information: Ambient (preferred)/Refrigerated (<24 hours)

Additional Information: A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.

 

Specimen Type: Blood spot

Supplies: Card-Blood Spot Collection (Filtration Paper) (T493)

Container/Tube:

Preferred: Collection card (Whatman Protein Saver 903 Paper)

Acceptable: PerkinElmer 226 (formerly Ahlstrom 226) filter paper or blood spot collection card

Specimen Volume: 5 Blood spots

Collection Instructions:

1. An alternative blood collection option for a patient 1 year of age or older is a fingerstick. For infants younger than 1 year, a heel stick should be used. See Dried Blood Spot Collection Tutorial for how to collect blood spots via fingerstick.

2. Let blood dry on the filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

3. Do not expose specimen to heat or direct sunlight.

4. Do not stack wet specimens.

5. Keep specimen dry.

Specimen Stability Information: Ambient (preferred)/Refrigerated

Additional Information:

1. Due to lower concentration of DNA yielded from blood spot, it is possible that additional specimen may be required to complete testing.

2. For collection instructions, see Blood Spot Collection Instructions

3. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777)

4. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800)

 

Specimen Type: Saliva

Patient Preparation: Patient should not eat, drink, smoke, or chew gum 30 minutes prior to collection.

Supplies: Saliva Swab Collection Kit (T786)

Specimen Volume: 1 Swab

Collection Instructions: Collect and send specimen per kit instructions.

Specimen Stability Information: Ambient 30 days

Additional Information: Due to lower concentration of DNA yielded from saliva, it is possible that additional specimen may be required to complete testing.


Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. The following documents are available:

-Informed Consent for Genetic Testing  (T576)

-Informed Consent for Genetic Testing (Spanish) (T826)

2. Molecular Genetics: Neurology Patient Information

Useful For

Establishing a molecular diagnosis in individuals with features of Rett syndrome and MECP2-related disorders

 

Identifying pathogenic variants within the MECP2 gene known to be associated with Rett syndrome and MECP2-related disorders, allowing for predictive testing of at-risk family members

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CULFB Fibroblast Culture for Genetic Test Yes No

Testing Algorithm

For skin biopsy or cultured fibroblast specimens, fibroblast culture testing will be performed at an additional charge. If viable cells are not obtained, the client will be notified.

Method Name

Sequence Capture and Targeted Next-Generation Sequencing followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing

Reporting Name

MECP2 Gene, Full Gene Analysis

Specimen Type

Varies

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Clinical Information

Methyl-CpG-binding protein 2 (MeCP2) is encoded by the MECP2 gene located on the X chromosome and plays an important role in gene regulation. MeCP2 binds methylated DNA and is involved in both transcription activation and repression of other gene targets. As MECP2-related disorders are X-linked, female and male patients with disease-causing variants in the MECP2 gene present with unique variable phenotypes. In female patients, disease-causing variants in MECP2 can be associated with classic Rett syndrome, variant or atypical Rett syndrome, or mild learning disabilities. Distinct phenotypes in male patients with disease-causing MECP2 variants include MECP2-duplication syndrome; MECP2-related severe neonatal encephalopathy; pyramidal signs, parkinsonism, and macroorchidism syndrome (PPM-X); and syndromic/non-syndromic intellectual disability. MECP2 analysis is useful in identifying germline variants in individuals with these clinical presentations.

 

Rett Syndrome:

Classic Rett syndrome and other variant MECP2-related disorders result from loss of MeCP2 expression. Rett syndrome is an X-linked, panethnic condition associated with neurologic regression after a 6- to 18-month period of initial normal development. Main clinical findings include stereotypic hand movements such as hand wringing and loss of purposeful hand movements, loss of acquired language, and gait abnormalities. Bruxism, irregular breathing, seizures, acquired microcephaly, and impaired sleep patterns are also common.

 

Greater than 99% of individuals with Rett syndrome are simplex cases due to a de novo variant or inheritance from a parent with germline mosaicism. Asymptomatic or very mildly affected carrier mothers of classically affected daughters have been reported due to nonrandom X chromosome inactivation.

 

MECP2 Duplication Syndrome:

MECP2 duplication syndrome involves variably sized duplications of the MECP2 gene (ranging in size from 0.3 to 4 Mb) that result in MeCP2 protein overexpression. It is characterized by severe intellectual disability, hypotonia, feeding difficulties, and progressive spasticity. Seizures and recurrent respiratory infections are commonly reported as well.

 

In contrast to Rett syndrome, most male patients with MECP2 duplication syndrome inherit the duplication from their asymptomatic mothers, although rare de novo variants may occur. Additionally, female patients with an MECP2 duplication that do not demonstrate skewed X-inactivation may present with variable features of MECP2-duplication syndrome.

Reference Values

An interpretive report will be provided.

Interpretation

All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

Clinical Reference

1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015 May;17(5):405-424

2. Sandweiss AJ, Brandt VL, Zoghbi HY: Advances in understanding of Rett syndrome and MECP2 duplication syndrome: prospects for future therapies. Lancet Neurol. 2020 Aug;19(8):689-698

3. Neul JL, Kaufmann WE, Glaze DG, et al: Rett syndrome: revised diagnostic criteria and nomenclature. Ann Neurol. 2010 Dec; 68(6):944-950

Day(s) Performed

Varies

Report Available

28 to 42 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

81302

88233-Tissue culture, skin, solid tissue biopsy (if appropriate)

88240-Cryopreservation (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MCP2Z MECP2 Gene, Full Gene Analysis 94229-2

 

Result ID Test Result Name Result LOINC Value
616577 Test Description 62364-5
616578 Specimen 31208-2
616579 Source 31208-2
616580 Result Summary 50397-9
616581 Result 82939-0
616582 Interpretation 69047-9
616583 Resources In Process
616584 Additional Information 48767-8
616585 Method 85069-3
616586 Genes Analyzed 82939-0
616587 Disclaimer 62364-5
616588 Released By 18771-6

Specimen Minimum Volume

Blood: 1 mL; Skin biopsy, cultured fibroblasts, dried blood spots, or saliva: See Specimen Required