Smith-Lemli-Opitz Syndrome (DHCR7) Sequencing, Fetal
Ordering Recommendation

Diagnostic fetal testing for pregnancies suspected to be affected with Smith-Lemli-Opitz syndrome (SLOS).

Polymerase Chain Reaction/Sequencing
Sun- Sat
5-10 days
New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
Specimen Required
Patient Preparation
Fetal Specimen: Two T-25 flasks at 80 percent confluent culture of amniocytes. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787.
Maternal Specimen:
Lavender (K2EDTA), Lavender (K3EDTA), Pink (K2EDTA), or Yellow (ACD Solution A or B). 
Specimen Preparation
Cultured Amniocytes: Fill flask with culture media. Transport two T-25 flasks at 80 percent confluent of culture amniocytes filled with culture media.
Maternal Specimen:
Transport 3 mL whole blood (Min: 1mL) 
Storage/Transport Temperature
Fetal Specimen: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of shipment due to liability of cells.
Maternal Specimen: Room temperature. 
Unacceptable Conditions
Maternal sample is recommended for proper test interpretation. Order Maternal Cell Contamination, Maternal Specimen. This can be arranged by contacting ARUP genetic counselors at (800) 242-2787 ext. 2141. Pateient History Form is available on the ARUP Web site or by contacting ARUP Client Services. 
Fetal Specimen: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal Specimen:
Ambient: 72 hours; Refrigerated: 1week; Frozen: Unacceptable 
Reference Interval
Interpretive Data
Background information for Smith-Lemli-Opitz Syndrome (DHCR7) Sequencing, Fetal:
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 DHCR7 gene.
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.
For quality assurance purposes, ARUP Laboratories will confirm the above result at no charge following delivery. Order Confirmation of Fetal Testing and include a copy of the original fetal report (or the mother's name and date of birth) with the test submission. Please contact an ARUP genetic counselor at (800) 242-2787 extension 2141
prior to specimen submission.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online at

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Hotline History
View Hotline History
CPT Code(s)
81405; 81265 Fetal Cell Contamination (FCC)
Component Test Code*Component Chart NameLOINC
0050548Maternal Contamination Study Fetal Spec59266-7
0050612Maternal Contam Study, Maternal Spec31208-2
2011705SLOS (DHCR7) Seq FE - Specimen31208-2
2011706SLOS (DHCR7) Seq FE - Interpretation55195-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • SLO
  • syndactyly