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Huntington Disease (HD) CAG Repeat Expansion, Fetal
Ordering Recommendation
Prenatal diagnostic testing for Huntington disease (HD). A completed Huntington Disease Consent Form, signed by the patient and ordering health care provider, is required. Documentation of a full penetrance HD-causing allele in a biological parent is required. Fetal testing will not be performed without prior approval; please contact an ARUP genetic counselor at 800-242-2787 ext. 2141.
Maternal cell contamination (MCC) analysis is required and performed at no additional charge. Order Maternal Cell Contamination, Maternal Specimen (0050608) on a maternal blood specimen.
For guidance on ordering maternal cell contamination studies, please refer to Maternal Cell Contamination (MCC) Analysis Guide.
New York DOH Approval Status
Specimen Required
Fetal Specimen: Amniotic fluid OR chorionic villi OR cultured amniocytes OR cultured chorionic villus sampling (CVS).
Maternal Specimen: Refer to Maternal Cell Contamination, Maternal Specimen (0050608) for maternal specimen requirements.
Transport: 10 mL amniotic fluid (min: 5 mL) OR
Chorionic villi 20 mg (min: 5mg) OR
Two T-25 flasks of 80% confluent cultured amniocytes OR
Two T-25 flasks of 80% confluent cultured chorionic villus sampling (CVS).
If submitting uncultured (direct) amniotic fluid or (direct) CVS and testing is desired on a cultured specimen, add Cell Culture for Genetic Testing (3020627). If transporting flasks, the client is responsible for maintaining backup cultures at the client institution. If ARUP receives cultured fetal cells below minimum confluence, Cell Culture for Genetic Testing (3020627) will be added by ARUP.
Preferred transport: Room temperature.
Preferred shipment: Within two days of collection or confluence.
Frozen specimens.
Counseling and informed consent are recommended for genetic testing. Consent forms are linked above.
New York Clients: Informed consent is required with submission.
Room temperature: 2 days; Refrigerated: 2 days; Frozen: Unacceptable
Methodology
Polymerase Chain Reaction (PCR) / Capillary Electrophoresis / Fragment Analysis
Performed
Varies
Reported
7-10 days
If culture is required, an additional 1 to 2 weeks is required for processing time.
Reference Interval
Interpretive Data
Refer to report.
Laboratory Developed Test (LDT)
Note
Hotline History
Hotline History
CPT Codes
81271; 81265 Fetal Cell Contamination (FCC)
Components
| Component Test Code* | Component Chart Name | LOINC |
|---|---|---|
| 0050548 | Maternal Contamination Study Fetal Spec | 59266-7 |
| 0050612 | Maternal Contam Study, Maternal Spec | 66746-9 |
| 3019938 | Huntington Disease Fetal Specimen | 31208-2 |
| 3019939 | Huntington Disease Fetal Allele 1 | 49637-2 |
| 3019940 | Huntington Disease Fetal Allele 2 | 49638-0 |
| 3019941 | Huntington Disease Fetal Interpretation | 50621-2 |
Aliases
- HD genetic testing
- HTT genetic testing
