CPT® Code 81330

Official Description

SMPD1 (sphingomyelin phosphodiesterase 1, acid lysosomal) (eg, Niemann-Pick disease, Type A) gene analysis, common variants (eg, R496L, L302P, fsP330)

Common Language Description

Molecular genetic testing, specifically for the SMPD1 gene, is a critical diagnostic tool used to identify mutations associated with Niemann-Pick disease, particularly Type A. The SMPD1 gene encodes the enzyme acid sphingomyelinase, which is essential for the breakdown of sphingomyelin into ceramide within lysosomes—cellular structures responsible for digesting and recycling various materials. This enzymatic activity is vital for maintaining the normal structure and function of cells and tissues. The SMPD1 gene is located on chromosome 11 and exhibits an autosomal recessive inheritance pattern, meaning that the mutation is typically inherited from both parents, but only the maternal copy of the gene is active in this context. Niemann-Pick disease arises from mutations in the SMPD1 gene, leading to over 100 identified mutations that can result in reduced or absent enzyme activity. This deficiency causes harmful accumulations of lipids, including cholesterol and sphingomyelin, particularly in the spleen, liver, and brain, ultimately disrupting cellular function and leading to cell death. Niemann-Pick disease, Type A, is notably more prevalent among individuals of Ashkenazi Jewish descent. The common variants associated with this condition include R496L, where arginine is replaced by leucine at codon 496; fsP330, characterized by a deletion of a single cytosine at codon 330; and L302P, where proline substitutes leucine at codon 302. Symptoms of Niemann-Pick disease typically manifest in infancy and may include feeding difficulties, abdominal distension, progressive loss of motor skills, and the presence of a cherry-red spot in the eye. Molecular genetic testing is recommended for individuals exhibiting symptoms consistent with Niemann-Pick disease or those with a family history of the disorder, facilitating early diagnosis and management of this serious condition.

1. Indications

The molecular genetic testing for the SMPD1 gene is indicated in the following scenarios:

Symptoms of Niemann-Pick Disease Individuals presenting with clinical symptoms associated with Niemann-Pick disease, such as feeding difficulties, abdominal swelling, loss of motor skills, and the presence of a cherry-red spot in the eye, may require testing to confirm a diagnosis.
Family History Testing is also indicated for individuals with a known family history of Niemann-Pick disease, as this genetic condition follows an autosomal recessive inheritance pattern, increasing the likelihood of the disorder in offspring.

2. Procedure

The procedure for molecular genetic testing of the SMPD1 gene involves several key steps:

Sample Collection A biological sample, typically blood or saliva, is collected from the patient. This sample contains the DNA necessary for genetic analysis.
DNA Extraction The DNA is extracted from the collected sample using standardized laboratory techniques to ensure purity and integrity for testing.
Mutation Analysis The extracted DNA is then subjected to analysis to identify specific mutations within the SMPD1 gene. This may involve techniques such as polymerase chain reaction (PCR) and sequencing to detect common variants, including R496L, fsP330, and L302P.
Data Interpretation The results of the genetic analysis are interpreted by qualified laboratory personnel, who assess the presence of any identified mutations and their potential implications for the patient's health.
Reporting A comprehensive report is generated, detailing the findings of the genetic testing, including any identified mutations and their association with Niemann-Pick disease. This report is then provided to the healthcare provider for further clinical decision-making.

3. Post-Procedure

After the molecular genetic testing procedure, patients may expect the following post-procedure considerations:

Results from the genetic testing typically take several days to weeks to process, depending on the laboratory's workload and the complexity of the analysis. Once results are available, healthcare providers will discuss the findings with the patient and their family, including the implications of any identified mutations. If a mutation associated with Niemann-Pick disease is found, further counseling and management options will be explored, which may include monitoring for symptoms, supportive care, and genetic counseling for family members. It is essential for patients to have follow-up appointments to address any questions or concerns regarding their results and to discuss potential next steps in their care.

Short Descr	SMPD1 GENE COMMON VARIANTS
Medium Descr	SMPD1 GENE ANALYSIS COMMON VARIANTS
Long Descr	SMPD1 (sphingomyelin phosphodiesterase 1, acid lysosomal) (eg, Niemann-Pick disease, Type A) gene analysis, common variants (eg, R496L, L302P, fsP330)
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
XU	Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service