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
  • Capillary Sequencing

Ordering

2502
4-5 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL) | Buccal Swabs

Billing

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

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.
  • Capillary Sequencing

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

Billing

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

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