Home
HelpTest Code LAB3243 L1CAM Single Gene Analysis
Additional Codes
L1CAM Gene
Clinical System Name
L1CAM Single Gene Analysis
Synonyms
L1 syndrome
X-Linked Hydrocephalus with Stenosis of the Aqueduct of Sylvius (HSAS, Aqueductal Stenosis, X-linked)
L1 Cell Adhesion Molecule
MASA Syndrome (Intellectual Disability, Aphasia, Shuffling Gait, and Adducted Thumbs)
SPG1 (X-Linked Complicated Hereditary Spastic Paraplegia Type 1)
X-Linked Corpus Callosum Agenesis
CRASH Syndrome
Sample Requirements
Preferred Specimen: Whole Blood
Container(s): Lavender Top/EDTA
Preferred Vol: 5.0 mL
Minimum Vol: 2.0 mL (1.0 mL for small infants)
Alternative Specimen: DNA
Container(s): Sterile Plastic Tube
Preferred Vol: 5 µg of purified DNA at a concentration of ≥50 ng/µL AND a volume of ≥100 µL
Alternative Specimen: Buccal Swab
Processing Instructions
Reject due to:
Spin: N
Aliquot: N
Temp: 2 - 8 C
Storage location: Refrigerate in CPA refrigerator Send Outs rack. Samples drawn on a Friday can be refrigerated until Monday shipment. Samples drawn on a Friday before a Monday holiday must have DNA extraction.
Off-site collection: Send whole blood refrigerated.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole blood | Room temp | 3 d |
| Whole blood | Refrigerated | 7 d |
| Whole blood | Frozen | N |
| Extracted DNA | Room temp | 3-4 d |
| Extracted DNA | Refrigerated | 1 y |
| Extracted DNA | Frozen | Indefinitely |
Availability
| STAT | TAT |
|---|---|
| N | 3 w |
Performing Laboratory
GeneDx
207 Perry Parkway
Gaithersburg, MD 20877
Phone Number: (301) 519-2100
Department
Department: Send Outs/Genetic
Phone Number: (206) 987-2563
Methodology
Method: Next-generation sequencing with CNV calling (NGS-CNV)
After gene specific filtering, data are analyzed to identify sequence variants and most deletions and duplications involving coding exons. Alternative sequencing or copy number detection methods are used to analyze regions with inadequate sequence or copy number data.
The technical sensitivity of sequencing is estimated to be >99% at detecting single nucleotide events. It will not reliably detect deletions greater than 20 base pairs, insertions or rearrangements greater than 10 base pairs, or low-level mosaicism. The copy number assessment methods used with this test cannot reliably detect copy number variants of less than 500 base pairs or mosaicism and cannot identify balanced chromosome aberrations. Assessment of exon-level copy number events is dependent on the inherent sequence properties of the targeted regions, including shared homology and exon size.
Reportable variants include pathogenic variants, likely pathogenic variants and variants of uncertain significance. Likely benign and benign variants, if present, are not routinely reported but are available upon request.
Reference Range
Interpretive report is provided.
Send Out Instructions
| Reference Test Name: | L1CAM Gene Sequencing & Del/Dup |
| Reference Lab Test Code: | 552 |
| Instructions: | Ship via FedEx Priority Overnight. Saturday deliveries are accepted. |
Description
This test performs sequencing and deletion/duplication analysis of L1CAM. Variants in the L1CAM gene result in a spectrum of allelic disorders with X-linked inheritance; L1 syndrome, MASA syndrome, and CRASH syndrome have been used to describe disorders on this spectrum.
Clinical Utility
Variants in the L1CAM gene result in a spectrum of allelic disorders with X-linked inheritance; L1 syndrome, MASA syndrome, and CRASH syndrome have been used to describe disorders on this spectrum. Congenital hydrocephalus and resultant macrocephaly due to stenosis of the aqueduct of Sylvius may occur as an isolated finding, but are frequently associated with other features, including hypoplastic or flexed, adducted thumbs. Patients exhibit varying degrees of intellectual disability and spastic paraplegia, particularly of the lower extremities. MASA syndrome includes intellectual disability, aphasia, shuffling gait, and adducted thumbs. In addition, CRASH syndrome includes corpus callosum agenesis/hypoplasia, intellectual disability, adducted thumbs, spastic paraplegia, and hydrocephalus. There can be significant phenotypic variability within families, with some males severely affected and diagnosed prenatally while others may have no macrocephaly and long survival. Approximately 5% of females harboring an L1CAM variant may exhibit clinical disease symptoms
A genetic diagnosis may have implications for treatment, management, recurrence risk, and family member testing.