Smith Lemli Opitz Syndrome, DHCR7 Gene, Full Gene Analysis, Varies

Casandra

Casandra Test Code MC35626Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID DHCRZ

Smith Lemli Opitz Syndrome, DHCR7 Gene, Full Gene Analysis, Varies

Clinical Use

Use

This test detects single nucleotide and copy number variants in the DHCR7 gene to assist in establishing a molecular diagnosis for Smith-Lemli-Opitz syndrome, guiding prognosis, clinical management, familial screening, and genetic counseling. It is particularly useful as follow-up for abnormal biochemical results suggestive of the syndrome and for predictive testing in at‑risk family members.

Special Instructions

Reflex tests may be performed at additional charge depending on specimen type—STR analysis, fibroblast culture (CULFB), amniotic fluid culture (CULAF), and maternal cell contamination testing (MATCC). Prenatal specimens, fibroblast specimens, or cord blood may trigger reflex testing; see ordering guidance and algorithm. The recommended first‑tier screen is plasma measurement of cholesterol precursors; customized panels or familial variant testing are available.

Limitations

Regions of DHCR7 may not be effectively evaluated by sequencing or deletion/duplication analysis due to high GC content, homology or repetitive sequences. Some regions may fail interrogation, noted in the report. Sensitivity is >99% for SNVs, >94% for small indels (95% for deletions up to 75 bp and insertions up to 47 bp. Post‑transplant specimens from allogeneic donors may interfere—consult lab. Saliva and blood spot specimens yield lower DNA quality/quantity and may result in incomplete analysis; additional specimen may be required.

Test Details

New York Approved