The laboratory genetic counselor at Diagnostic Cytogenetics Inc. is available to answer any questions about appropriate testing and to research the best options for your patient.
Indication for Testing
• Multiple miscarriages or infertility.
• Previous or family history of chromosomal abnormality.
• Confirmation of prenatal diagnosis.
• Child/newborn with multiple congenital abnormalities and/or intellectual disability that is suggestive of a chromosomal defect
• Abnormal growth or development.
• Ambiguous genitalia.
Chromosome Analysis Detects:
• Aneuploidy (monosomy, trisomy)
• Deletions and duplications (>5Mb)
Chromosome Analysis Does Not Detect:
• Deletions or duplications that are too small to be seen by microscope (<5Mb)
Five cells are completely analyzed and at least three karyograms are prepared. Additional chromosome analysis and special banding techniques are employed as needed.
In our standard analysis:
• G-banded chromosomes from 20 metaphase cells are examined.
For our newborn analysis:
• G-banded chromosomes from 5 cells obtained by 48 hour culture are examined.
• If aneuploid, 15 additional cells are examined and the study is complete.
• If normal, a synchronized culture is prepared to obtain extended chromosomes, and an additional 15 cells are examined from the synchronized culture.
If mosaicism is suspected, G-banded chromosomes from at least 50 cells are examined.
Please see our FISH page for our full test menu.
Aneuvysion FISH Panel
Aneuvysion Fluorescent In Situ Hybridization (FISH) testing is suggested for newborns with multiple congenital abnormalities that suggest aneuploidy of chromosomes X, Y, 13, 18, and 21.
Probe Target Abnormality RB1 Trisomy 13 D18Z1 Trisomy 18 D21S259 Trisomy 21 DXZ1 Sex Chromosome Aneuploidy DYZ3 Sex Chromosome Aneuploidy
Preliminary results are available on an average of 24 hours after specimen receipt.
FISH results are considered preliminary until confirmed by classical cytogenetic analysis.
Microdeletion/Microduplication Syndrome Probes
FISH on metaphase cells can also be performed to identify the following microdeletion/microduplication syndromes:
Syndrome Name Chromosome Location Probe/Gene Locus Wolf-Hirschhorn syndrome 4p16.3 D4S96 Cri du chat syndrome 5p15.2 D5S23 Williams syndrome 7q11.23 Elastin Retinoblastoma 13q14.2 RB1 Prader-Willi/Angelman syndrome 15q11.2-q13 SNRPN/D15S10 Smith-Magenis syndrome 17p11.2 FLI1 and RAI1 Miller-Dieker syndrome 17p13.3 LIS1 22q11.2 Deletion Syndrome (DiGeorge, Velocardiofacial Syndrome) 22q11.2 TUPLE1 (D22S553, D22S609, D22S942) Steroid Sulfatase Deficiency/X-linked Ichthyosis Xp22.3 STS Kallmann Syndrome 1 Xp22.3 KAL1
Subtelomeric FISH is useful for detecting subtle or submicroscopic deletions at the terminal chromosome regions in patients with unexplained intellectual disability (ID) or developmental delay (DD). This test may also detect duplications and balanced rearrangements involving these terminal chromosome regions.
Subtelomeric testing will only be performed subsequent to normal cytogenetic analysis. This testing is performed on metaphase cells.
Fluorescence in-situ Hybridization (FISH) utilizes DNA probes that bind to a specific region of a chromosome. These probes produce bright colored signals visible under a fluorescence microscope.
These probes are applied to metaphase cell or interphase cell preparations and allowed to hybridize for 12-16 hours. Detection reagents and fluorescent stains are then applied to allow visualization of the probes.
The slides are examined on a fluorescence microscope. Ten to fifty (depending on the probe used) metaphase cells are scored. Two hundred interphase cells are scored.
Test Turnaround Time* CPT Codes** Chromosome Analysis 5-7 days 88230, 88262, 88280, 88289, 88291 Chromosome Analysis, Newborn 5-7 days, 2 days for abnormal aneuploid cases 88230, 88261, 88280×2, 88285, 88291 Aneuvysion FISH 24 hours for preliminary, 5-7 days for final (reported with chromosome analysis) 88377×2 Metaphase FISH 5-7 days 88377
*All turnaround times are business days from specimen receipt to report issued.
**Some codes may vary or be charged in multiple units, depending on patient-specific testing parameters.
If no cells are available for analysis, only set up fees will be billed.
Submitting a Sample
Peripheral Blood: 5-10 ml of blood in a preservative free sodium-heparin (green-top) tube. Invert tube to mix. Prometaphase analysis will be performed on all specimens unless otherwise specified.
Newborns: Minimum of 1 ml peripheral blood in a preservative free sodium-heparin (green top) tube. Invert tube to mix well.
Molecular studies: Samples for molecular studies will be forwarded to an outside laboratory for testing. Please include an additional 5-10 ml blood in an EDTA (lavender-top) tube.