Confirm a clinical or biochemical diagnosis of Smith-Lemli-Opitz syndrome(SLOS) or carrier screening for SLOS.
Polymerase Chain Reaction/Sequencing
Lavender (EDTA), pink (K2EDTA), or Yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Background information for Smith-Lemli-Opitz Syndrome (DHCR7) Sequencing:
Characteristics: Smith-Lemli-Opitz syndrome (SLOS) is caused by mutations in the DHCR7 gene that disrupt the final step of cholesterol biosynthesis. Affected individuals typically have elevated serum concentration of 7-dehydrocholesterol (7-DHC). Characteristic findings include growth deficiency, postaxial polydactyly, 2-3 toe syndactyly, intellectual disability, cardiac defects, feeding difficulty, congenital cataracts, sensorineural hearing loss, and characteristic facial features. Males with SLOS may have genitourinary anomalies such as hypospadias, cryptorchidism or undermasculinization of the external genitalia.
Incidence: 1 in 10,000- 1 in 60,000 live births.
Inheritance: Autosomal recessive.
Cause: Pathogenic germline mutations in the DHCR7gene.
Clinical Sensitivity: 96 percent.
Methodology: Bidirectional sequencing of the entire DHCR7 coding region and intron/exon boundaries.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations, deep intronic mutations, mutations in non-coding exons 1-2, and large deletion/duplications will not be detected. Mutations in genes other than DHCR7 are not evaluated.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
Laboratory Developed Test (LDT)
|Component Test Code*||Component Chart Name||LOINC|
|2011458||SLOS (DHCR7) Seq - Specimen||55195-2|
|2011459||SLOS (DHCR7) Seq - Interpretation||31208-2|