Smith-Lemli-Opitz Syndrome

Smith-Lemli-Opitz Syndrome (SLOS) is a severe developmental disorder. The clinical spectrum is wide and includes both pre- and post-natal growth retardation, mild to severe mental retardation, multiple congenital malformations (both major and minor), and characteristic facies. Frequent additionally observed findings include: microcephaly, micrognathia, cleft palate, cardiac defects, abnormal external genitalia, post-axial polydactyly, and 2-3 toe syndactyly. Infants are often hypotonic with poor suck, and have failure to thrive. Older children commonly have behavioral concerns including autism, hyperactivity, aggression, and self-injurious behavior. Children with SLOS have elevated serum 7-dehydrocholesterol (7-DHC) levels and low levels of serum cholesterol. In cholesterol biosynthesis, 7-DHC is converted to cholesterol by the enzyme 3b-hydroxysterol D7-reductase (sterol delta-7-reductase), which is encoded by the gene DHCR7. DHCR7 is also required to reduce 7-dehydrodesmosterol to desmosterol. Mutations in the DHCR7 gene underlie SLOS.

Tests Available

Forms and Documents

Test Info Sheet Test Requisition Form

Test Details

  • Confirmation of a suspected clinical diagnosis
  • Carrier testing in siblings or other relatives

Ordering

2502
4-5 weeks
2-5 mL Blood - Lavender Top Tube
Buccal Swabs

*Reporting times are typical, but could be extended in situations outside GeneDx's reasonable control.

Billing

81405x1
No
Yes
  • 759.89 Other Congenital malformation syndromes affecting multiple systems
For price inquiries please email zebras@genedx.com

**The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

References

  1. Witsch-Baumgartner et al., (2000) Am J Hum Genet 66:402-412
  2. Correa-Cerro et al., (2005) Mol Gen Metab 84:112-26
  3. Yu, H. and Patel, S.B., (2005) Clin Genet 68:383-91

Forms and Documents

Specimen Requirements Test Info Sheet Test Requisition

Test Details

  • Full gene sequencing for fetuses with increased 7-DHC levels measured in amniotic fluid or CVS tissue.
  • In the case of ultrasound findings and/or abnormal maternal serum screening suggestive of SLOS and no family history, prenatal measurement of 7-DHC levels is recommended as a first step.
  • Mutation-specific testing for fetuses with a family history of two known DHR7 mutations.

Ordering

2503
2-3 weeks
20 mL Amniotic Fluid
20 mg CVS | 2 T25 flasks of cultured amniocytes | 2 T25 flasks of cultured chorionic villi | 3 Ug DNA Concentration

*Reporting times are typical, but could be extended in situations outside GeneDx's reasonable control.

Billing

81405x1, 81265x1
No
Yes
For price inquiries please email zebras@genedx.com

**The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

References

  1. Witsch-Baumgartner et al., (2000) Am J Hum Genet 66:402-412
  2. Correa-Cerro et al., (2005) Mol Gen Metab 84:112-26;
  3. Yu, H. and Patel, S.B., (2005) Clin Genet 68:383-91
  4. Goldenberg A, et al., Am J Med Genet A. 2004; 124: 423–6.
  5. Rossiter et al., (1995) Am J Med Genet 56:272-5.
  6. Irons, M. (Updated [Oct. 24, 2007]) Smith-Lemli-Opitz Syndrome In: GeneReviews at Genetests: Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1997- 2010. Available at http://www.genetests.org