Gaucher Disease, DNA Analysis

Test Details

Use

This assay will detect carriers of Gaucher disease in the Ashkenazi Jewish population. Enzyme testing is the preferred test to detect affected individuals. DNA testing may be used to confirm affected status.

Special Instructions

If cultured cells are needed, anadditional 7-12 days may be required. Additional culture fee may be included.

Limitations

To determine affected status, biochemical testing is recommended. This assay detects ∼95% of the mutations responsible for Gaucher disease type I and 50% to 60% of types II and III (childhood and juvenile onset) in the Ashkenazi Jewish population. Seventy-five percent of mutations in non-Jewish Caucasians are also detected. The frequency of the various glucocerebrosidase mutations can vary significantly between different ethnic groups. Since this analysis does not detect all mutations, results must be combined with clinical information for the most accurate interpretation. This test is not appropriate for determining affected status for childhood/juvenile onset disease.

Methodology

Polymerase chain reaction (PCR); primer extension; flow-sorted bead array analysis for eight mutations in the glucocerebrosidase gene. The mutations tested include: N370S (A1226G), L444P (C1448T), D409H (G5957C), V395L (5912T), 84GG (G-GG), IVS2+1 (insA), R496H (G1604A), and 55 bp deletion (C1263del).

References

American College of Obstetricians and Gynecologists Committee on Genetics. ACOG committee opinion. N° 298, August 2004. Prenatal and preconceptional carrier screening for genetic diseases in individuals of Eastern European Jewish descent. Obstet Gynecol. 2004 Aug; 104(2):425-428. 15292027
Monaghan KG, Feldman GL, Palomaki GE, Spector EB; Ashkenazi Jewish Reproductive Screening Working Group; Molecular Subcommittee of the ACMG Laboratory Quality Assurance Committee. Technical standards and guidelines for reproductive screening in the Ashkenazi Jewish population. Genet Med. 2008 Jan; 10(1):57-72. 18197058

Additional Information

Gaucher disease (OMIM 230800) is an autosomal recessive disorder caused by a decrease in the levels of the enzyme glucocerebrosidase. Decreased levels of glucocerebrosidase can result in visceral changes, such as organomegaly and thrombocytopenia, and skeletal changes, such as bone lesions. There are three subtypes of Gaucher disease. Type 1 is the most common subtype. Individuals affected with type 1 may have onset of symptoms in adolescence, though some remain asymptomatic well into adulthood. Type 1 is effectively treated through enzyme replacement therapy.

Specimen Requirements

Information on collection, storage, and volume

Specimen

Whole blood, amniotic fluid, chorionic villus sample (CVS) (submission of maternal blood is required for fetal testing), or LabCorp buccal swab kit (buccal swab collection kit contains instructions for use of a buccal swab)

Volume

7 mL whole blood, 10 mL amniotic fluid, 20 mg CVS, or LabCorp buccal swab kit

Minimum Volume

3 mL whole blood, 5 mL amniotic fluid, 10 mg CVS, or two buccal swabs

Container

Lavender-top (EDTA) tube, yellow-top (ACD) tube, sterile plastic conical tube or two confluent T25 flasks for fetal testing, or LabCorp buccal swab kit

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; one buccal swab; wet buccal swab