Johns Hopkins DNA Diagnostic Laboratory

PLEASE NOTE: Informed consent from the patient is required prior to ordering a genetic test. The DNA Diagnostic Lab's consent is located on the second page of the requisition form. There is also a patient brochure, "Things Every Patient Should Know Before Consenting to a Genetic Test", available for download.

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Hyperalphalipoproteinemia (Elevated HDL)

Gene:    SCARB1  (SR-B1 protein)
Test:   Genotyping for rs4238001 (c.4G>A; p.Gly2Ser); Direct mutation analysis by DNA sequencing of SCARB1 exon 1
CPT Codes:
  83891 x 1; 83898 x 1; 83904 x 2; 83909 x 2; 83912 x 1

2013 CPT Code:  81479

Sensitivity:    The rs4238001 variant has been shown to account for 16% of SR-B1 protein level variation among individuals with HDL-C>60mg/dl (West et al, 2009, J Clin Endocrinol Metab, 94:1451).  Though the frequency varies by ethnicity, approximately 13% of the population are carriers
Cost:   $302 per individual blood sample
Turn Around Time:    Approximately 2 weeks
Special Considerations/ Clinical Utility    SR-B1 is the predominant receptor for HDL cholesterol.  It plays an important role in reverse cholesterol transport (removal from cells and eventual disposal via the liver) and is highly expressed in the liver and steroidogenic tissues. 

 rs4238001 is associated with SR-B1 deficiency, and is considered a risk or susceptibility allele for elevated HDL-C.  Elevated HDL-C is typically thought to have a protective effect against cardiovascular disease in the face of elevated LDL-C; however, there is a subset of individuals with elevated HDL-C who remain at risk for cardiovascular disease. 

 If HDL-C is elevated because of SR-B1 deficiency, this protective effect is diminished.  In this patient population, it is therefore advisable to consider treatment with cholesterol lowering medications to an appropriate LDL-C target.  

Link to Sample Requirements

Link to Requisition and Billing forms

Link to clinical information on Pfeiffer Syndrome.

Link to Patient and Family Page for general resources on genetic testing.