FISH, Miller-Dieker

Test Code

14612

Physician Attestation of Informed Consent

This germline genetic test requires physician attestation that patient consent has been received if ordering medical facility is located in AK, DE, FL, GA, IA, MA, MN, NV, NJ, NY, OR, SD or VT or test is performed in MA.

Preferred Specimen

5 mL whole blood collected in a sodium heparin (green-top) tube

Minimum Volume

1 mL

Other Acceptable Specimens

Sodium heparin (royal blue-top) tube • Sodium heparin lead-free (tan-top) tube

Instructions

3-5 mL whole blood collected in a sodium heparin tube

Transport Temperature

Room temperature

Specimen Stability

Specimen viability decreases during transit. Send specimen to testing lab for viability determination. Do not freeze. Do not reject.

Methodology
Fluorescence in situ Hybridization (FISH)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Daily; Report available: 5-7 days

Clinical Significance

This test uses fluorescence in situ hybridization (FISH) to detect microdeletions in chromosome 17p13.3 in individuals with clinically suspected Miller-Dieker syndrome (MDS). MDS is a developmental disorder characterized by distinct facial features along with a combination of neurologic findings, including "classic lissencephaly" (or smooth brain), seizures, developmental delay, and intellectual disability [1].

Individuals with MDS may also have abnormalities in the heart and kidneys as well as omphalocele. Prognosis for MDS is poor; most children with MDS die before 2 years of age [1,2].

This test detects the loss of PAFAH1B1, one of the genes that are associated with the clinical manifestations of MDS. Since similar clinical syndromes can be caused by pathogenic variants in PAFAH1B1, tests such as chromosomal microarray and gene sequencing may find abnormalities even if FISH does not.

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Brock S, et al. PAFAH1B1-related lissencephaly/subcortical band heterotopia. In: Adam MP, et al., ed. GeneReviews®. University of Washington; March 3, 2009. Accessed September 30, 2021. https://www.ncbi.nlm.nih.gov/books/NBK5189
2. Blazejewski SM, et al. Front Genet. 2018;9:80.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.