Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome is a highly variable inherited disorder affecting cholesterol metabolism. It causes behavioral and learning problems, as well as a variety of congenital malformations.


Quick Reference
Test Code: 2180 Test Name: DHCR7 seq and del/dup TAT 2-4 weeks Gene: 1
Test Code: 2182 Test Name: DHCR7 specific site analysis TAT 7-14 days Gene: 1

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Mutation Detection Rate

This test can detect >99.9% of described mutations in DHCR7, when present (analytic sensitivity).

Test Description

Our Smith-Lemli-Opitz syndrome genetic testing includes next generation sequencing (NGS) and deletion/duplication analysis of the DHCR7 gene. Genomic deoxyribonucleic acid (gDNA) is isolated from the patient’s specimen using a standardized kit and quantified. Sequence enrichment of the targeted coding exons and adjacent intronic nucleotides is carried out by a bait-capture methodology using long biotinylated oligonucleotide probes, followed by polymerase chain reaction (PCR) and NGS. Additional Sanger sequencing is performed for any regions missing, or with insufficient read depth coverage for reliable heterozygous variant detection. Reportable small insertions and deletions, potentially homozygous variants, variants in regions complicated by pseudogene interference, and single nucleotide variant calls not satisfying 100x depth of coverage and 40% het ratio thresholds are verified by Sanger sequencing.1 This test targets detection of DNA sequence mutations in all coding domains, and well into the 5’ and 3’ ends of all the introns and untranslated regions. Gross deletion/duplication analysis is performed utilizing a targeted chromosomal microarray.


1. Mu W, et al. Sanger confirmation is required to achieve optimal sensitivity and specificity in next-generation sequencing panel testing. J Mol Diagn. 2016. 18(6):923-932.

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