Tay-Sachs Disease (HEXA) 7 Mutations, Fetal
0051429
Ordering Recommendation
Molecular diagnosis of common pathogenic mutations and pseudodeficiency alleles in prenatal samples when the targeted mutations have been confirmed in the parents.
Mnemonic
HEXA FE
Methodology
Polymerase Chain Reaction/Primer Extension
Performed
Tue, Thu
Reported
7-10 days  
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
  
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.  
Unacceptable Conditions
  
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
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 Disease (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:
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.



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  
Note
 
CPT Code(s)
81255; Fetal Cell Contamination (FCC): 81265
Components
Component Test Code*Component Chart Name
0050548Maternal Cell Contamination, Fetal Spec
0050612Maternal Cell Contam, Maternal Spec
0051430Tay-Sachs Disease (HEXA) 7 Mut, Allele 1
0051431Tay-Sachs Disease (HEXA) 7 Mut, Allele 2
0051432Tay-Sachs Disease (HEXA) 7 Mut, Interp
0051763Tay-Sachs Disease (HEXA) 7 Mut,FetalSpec
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • HEXA fetal mutation testing