- Patient Preparation
- Fetal Specimen: Two T-25 flasks at 80% confluency of cultured amniocytes. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787. Or amniotic fluid.
AND Maternal Cell Contamination Specimen: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Cultured Amniocytes: Fill flasks with culture media. Transport two T-25 flasks at 80% confluency of cultured amniocytes. Backup cultures must be retained at the client's institution until testing is complete.
OR Amniotic Fluid: Transport 10 mL unspun fluid. (Min: 5 mL)
AND Maternal Cell Contamination Specimen: Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Cultured Amniocytes: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of shipment due to liability of cells.
Amniotic fluid: Room temperature.
Maternal Cell Contamination Specimen: Room temperature.
- Unacceptable Conditions
- Maternal specimen is recommended for proper test interpretation. Order Maternal Cell Contamination. Patient History Form is available on the ARUP Web site or by contacting ARUP Client Services.
- Fetal Specimen: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal Cell Contamination Specimen: Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Lysosomal storage disease that in its severe form leads to loss of motor skills beginning at three to six months of age that progresses to blindness, seizures and total incapacitation and death by 4 years of age. A milder disease with later onset and slower progression is seen in affected adults. Adult-onset Tay-Sachs is associated with variable neurological findings including: progressive dystonia, spinocerebellar degeneration, motor neuron disease and bipolar form of psychosis.
Incidence: 1 in 3000 Ashkenazi Jewish individuals, unknown in other ethnicities.
Inheritance: Autosomal recessive.
Cause: Pathogenic HEXA gene mutations.
Mutations Tested: Four severe: 7.6kb del, c.1073+1G>A, p.Y427Ifs (c.1274_1277dupTATC), c.1421+1G>C; one mild: p.G269S (c.805G>A); and two pseudodeficiency alleles: p.R247W (c.739C>T) and p.R249W (c.745C>T).
Clinical Sensitivity: 94 percent in Ashkenazi Jewish individuals, unknown in other ethnicities.
Methodology:Multiplex polymerase chain reaction and Detection Primer Extension.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: HEXAmutations, other than those specified above, will not be detected. Diagnostic errors can occur due to rare sequence variations.
For quality assurance purposes, ARUP Laboratories will confirm the above result at no charge following delivery. Order Confirmation of Fetal Testing and include a copy of the original fetal report (or the mother's name and date of birth) with the test submission. Please contact an ARUP genetic counselor at (800) 242-2787 extension 2141 prior to specimen submission.
See Compliance Statement C: www.aruplab.com/CS
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0050548||Maternal Cell Contamination, Fetal Spec||31208-2|
|0050612||Maternal Cell Contam, Maternal Spec||31208-2|
|0051430||Tay-Sachs Disease (HEXA) 7 Mut, Allele 1||38900-7|
|0051431||Tay-Sachs Disease (HEXA) 7 Mut, Allele 2||38900-7|
|0051432||Tay-Sachs Disease (HEXA) 7 Mut, Interp||51773-0|
|0051763||Tay-Sachs Disease (HEXA) 7 Mut,FetalSpec|
- HEXA fetal mutation testing