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BETA v.3.0

2025 CPT code 81304

MECP2 (methyl CpG binding protein 2) (eg, Rett syndrome) gene analysis; duplication/deletion variants

This code should be used specifically for duplication/deletion analysis of the MECP2 gene. For full sequence analysis, use 81302. For known familial variants, use 81303. Procedures performed before cell lysis should be reported separately.

Modifier 26 can be appended if only the interpretation and report are performed by a physician or other qualified healthcare professional.

Medical necessity for this test is determined by the patient's clinical presentation and/or family history. It is often used when a clinical suspicion of Rett syndrome remains despite negative results from standard MECP2 mutation analysis.

The laboratory analyst performs all technical aspects of the analysis, from cell lysis and nucleic acid extraction to amplification, detection, and analysis of the MECP2 gene for duplication/deletion variants. Physician interpretation of results can be reported separately.

In simple words: This lab test looks for changes in the MECP2 gene, which is linked to Rett syndrome. It specifically checks for large pieces of the gene that are either missing (deleted) or duplicated. This test is often done when a standard genetic test doesn't find any problems, as it can pick up changes that other tests miss.

This test analyzes the MECP2 gene for duplications and deletions. Typically, all listed variants are tested, however, the lists are not exclusive. If other variants are also tested, they would be included in the procedure and not reported separately. This includes all analytical services performed (eg, cell lysis, nucleic acid stabilization, extraction, digestion, amplification, and detection). Any procedures required prior to cell lysis (eg, microdissection) should be reported separately.

Example 1: A female infant exhibits developmental regression, including loss of purposeful hand skills and acquired microcephaly. Initial genetic testing was negative for common MECP2 mutations. 81304 is performed to evaluate for copy number variants (duplications/deletions) in the MECP2 gene, which may explain the observed symptoms, even if the sequencing analysis (81302) didn't reveal any point mutations., A young girl presents with symptoms suggestive of Rett syndrome, including stereotypical hand movements and breathing irregularities. After a negative full sequence analysis of MECP2, 81304 is ordered to assess for the possibility of duplications or deletions within the gene that might account for the clinical presentation., A family has a history of Rett syndrome. A female relative wants to know her carrier status. 81304 is performed as part of the carrier screening process, alongside full gene sequencing if appropriate.

Documentation should include relevant clinical findings, family history (if applicable), and prior genetic testing results. The report should include the laboratory methodology, the specific variants analyzed, and the interpretation of the results.

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