CPT® Code 81324

Official Description

PMP22 (peripheral myelin protein 22) (eg, Charcot-Marie-Tooth, hereditary neuropathy with liability to pressure palsies) gene analysis; duplication/deletion analysis

Common Language Description

The CPT® Code 81324 pertains to the molecular genetic testing specifically aimed at analyzing the PMP22 gene, which is crucial in the context of Charcot-Marie-Tooth disease and hereditary neuropathy with liability to pressure palsies. The PMP22 gene is located on chromosome 17 and encodes for the peripheral myelin protein 22, a vital component of the myelin sheath that envelops nerve cells. This protein plays a significant role in the transmission of nerve impulses, which is facilitated by Schwann cells that are also integral to the myelin sheath. The testing performed under this code focuses on identifying specific mutations within the PMP22 gene, particularly through duplication and deletion analysis. Mutations in the PMP22 gene can manifest in two primary inheritance patterns: autosomal recessive and autosomal dominant. In the autosomal recessive pattern, an individual must inherit a mutated gene from both parents to exhibit symptoms of the disease. Conversely, in the autosomal dominant pattern, the presence of just one mutated gene copy is sufficient to cause the disease. The most prevalent form of Charcot-Marie-Tooth disease, known as Type 1A, is characterized by a duplication of the PMP22 gene, leading to an overproduction of the PMP22 protein. This overproduction disrupts the normal processing of the protein, resulting in a reduction of functional PMP22, which in turn decreases myelin integrity and impairs nerve function. Additionally, hereditary neuropathy with liability to pressure palsies is often associated with a reduction in gene dosage, where one copy of the PMP22 gene is lost, leading to diminished levels of the protein. This condition can also arise from mutations that produce an unstable protein that degrades rapidly, leaving the myelin sheath vulnerable to damage from external pressure. The analysis performed under CPT® Code 81324 is essential for diagnosing these genetic conditions and understanding the underlying genetic factors that contribute to nerve dysfunction and related symptoms.

1. Indications

The molecular genetic testing for PMP22 gene analysis is indicated for the following conditions:

Charcot-Marie-Tooth Disease This hereditary condition is characterized by progressive muscle weakness and atrophy, primarily affecting the distal muscles of the limbs.
Hereditary Neuropathy with Liability to Pressure Palsies This condition involves recurrent episodes of weakness and sensory loss due to pressure on the nerves, often leading to temporary paralysis.

2. Procedure

The procedure for PMP22 gene analysis involves several critical steps to ensure accurate results. First, a sample is collected from the patient, typically through a blood draw or saliva sample, which contains the DNA necessary for analysis. Next, the laboratory performs a duplication/deletion analysis of the PMP22 gene. This analysis specifically looks for any duplications or deletions in the gene that may contribute to the aforementioned neuropathies. The laboratory utilizes advanced molecular techniques, such as polymerase chain reaction (PCR) and quantitative PCR, to detect these genetic alterations. Once the analysis is complete, the results are interpreted by a qualified geneticist or molecular pathologist. They will assess whether any duplications or deletions are present in the PMP22 gene and correlate these findings with the patient's clinical symptoms and family history. If a mutation is identified, it may provide valuable information regarding the diagnosis, prognosis, and potential treatment options for the patient. The results are then documented in a comprehensive report, which is shared with the referring physician to guide further clinical management.

3. Post-Procedure

After the PMP22 gene analysis is completed, patients may not require any specific post-procedure care related to the genetic testing itself. However, it is essential for the healthcare provider to discuss the results with the patient, including any identified mutations and their implications for the patient's health and family members. Genetic counseling may be recommended to help the patient and their family understand the results, the inheritance patterns of the conditions, and the potential for future health monitoring or interventions. Additionally, if a mutation is found, the healthcare provider may suggest follow-up testing for family members to assess their risk of developing similar conditions.

Short Descr	PMP22 GENE DUP/DELET
Medium Descr	PMP22 GENE ANAL DUPLICATION/DELETION ANALYSIS
Long Descr	PMP22 (peripheral myelin protein 22) (eg, Charcot-Marie-Tooth, hereditary neuropathy with liability to pressure palsies) gene analysis; duplication/deletion analysis
Status Code	Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days	XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC)	9 - Not Applicable
Multiple Procedures (51)	9 - Concept does not apply.
Bilateral Surgery (50)	9 - Concept does not apply.
Physician Supervisions	09 - Concept does not apply.
Assistant Surgeon (80, 82)	9 - Concept does not apply.
Co-Surgeons (62)	9 - Concept does not apply.
Team Surgery (66)	9 - Concept does not apply.
Diagnostic Imaging Family	99 - Concept Does Not Apply
CLIA Waived (QW)	No
APC Status Indicator	Service Paid under Fee Schedule or Payment System other than OPPS
Type of Service (TOS)	5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS)	T1H - Lab tests - other (non-Medicare fee schedule)
MUE	1
CCS Clinical Classification	234 - Pathology

90	Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
59	Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25.
GA	Waiver of liability statement issued as required by payer policy, individual case
GW	Service not related to the hospice patient's terminal condition