Ordering Recommendation

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

Mnemonic
DHCR7 FE
Methodology

Polymerase Chain Reaction/Sequencing

Performed

Sun- Sat

Reported

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
Collect

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
Remarks

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.

Stability

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 www.aruplab.com.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81405; 81265 Fetal Cell Contamination (FCC)

Components
Component Test Code* Component Chart Name LOINC
0050548 Maternal Contamination Study Fetal Spec 59266-7
0050612 Maternal Contam Study, Maternal Spec 31208-2
2011705 SLOS (DHCR7) Seq FE - Specimen 31208-2
2011706 SLOS (DHCR7) Seq FE - Interpretation 55195-2
* 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.
Aliases
  • SLO
  • syndactyly
Smith-Lemli-Opitz Syndrome (DHCR7) Sequencing, Fetal