ARUP's Laboratory Test Directory

Tay-Sachs (HEXA) 7 Mutations, Fetal : 0051429
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Time Sensitive
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Patient History for Fetal Molecular Testing


Mnemonic: HEXA FE

Ordering Recommendation: Diagnostic testing for Tay-Sachs disease.
Methodology: Polymerase Chain Reaction/ASPE Bead Array
Performed: Tue, Thu
Reported: 7-10 days
Specimen Required: Collect: 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.

Remarks: 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.

Stability (collection to initiation of testing): Fetal Specimen: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal Cell Contamination Specimen: Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval:
By report
Interpretive Data: Background information for Tay-Sachs (HEXA) 7 Mutations, Fetal:
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: Deleterious HEXA gene mutations.
Mutations Tested: Four severe (Delta7.6kb, IVS9(+1)G>A, 1278insTATC, IVS12(+1)G>C), one mild (G269S), and two pseudodeficiency alleles (R247W and R249W).
Clinical Sensitivity: 94 percent in Ashkenazi Jewish individuals, unknown in other ethnicities.
Methodology: PCR and allele specific primer extension by bead array with fluorescence detection.
Analytical sensitivity and specificity: Greater than 99 percent.
Limitations: HEXA mutations other than those specified above will not be detected. Rare diagnostic errors may occur due to primer site mutations.

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.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
CPT Code(s): 81255; Fetal Cell Contamination (FCC): 81265