Karyotyping & FISH for Chromosome 18

Omics test Model
Test Code FVB05C
Test Summary Karyotyping - Provides holistic picture of the 23 pairs of chromosome allowing simultaneous examination of all chromosomes. Fluorescence in situ hybridization (FISH) is performed for aneuploidy detection of chromosome 18
Turn Around Time 15 days
Acceptable Sample Types Whole Blood (EDTA)
NY Approved No
Accreditations CAP , ISO 15189 (NABL)
*TAT starts after the sample and all required sample information is received at the processing laboratory.

**The CPT codes listed are in accordance with Current Procedural Terminology, a publication of the American Medical Association, and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party.

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Test Code: FVB05C
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Test Description

A karyotype test is a type of genetic testing. It looks at the size, shape, and number of chromosomes in a sample of cells from your body. Chromosomes are found in the cell nucleus, which is like the command center of a cell. Chromosomes contain your genes. Genes carry information, called DNA, that controls what you look like and how your body works.You inherit your chromosomes from your parents. Normally, all your cells (except for egg and sperm cells) have a set of the same 46 chromosomes. The chromosomes are grouped into 23 pairs. Each pair has two chromosomes, one coming from each parent. You may develop certain genetic disorders if your cells:

  • Are missing whole chromosomes or pieces of chromosomes
  • Have extra chromosomes or extra pieces of chromosomes

FISH - Rapid detection of aneuploidy involving chromosome 18. Assay offered in conjunction with chromosome study.

Indications for Testing

Karyotyping

  • Abnormal fetal ultrasound and presenceof soft markers like hypoplastic nasal bone, Increased NT, Echogenic bowel etc.
  • Maternal serum screening positive for chromosome aneuploidies
  • NIPT positive for chromosome aneuploidies
  • Parental chromosomal rearrangement or mosaicism
  • Previous history of recurrent miscarriages
  • Previous fetus/baby with chromosoma abnormality

FISH

The FISH analysis does not detect structural chromosome abnormalities, mosaicism, and other numerical chromosome abnormalities (excluding 13, 18, and 21). The American College of Medical Genetics recommends that irreversible therapeutic action should not be initiated on the basis of FISH results alone.

Condition Description

Karyoytyping

A karyotype test looks for unusual changes in chromosomes. It may be used to:

  • Check an unborn baby for chromosome problems
  • Check you and/or your family members for specific chromosome problems if you:
    • Have a genetic disorder that runs in your family
    • Have symptoms that may be from a genetic disorder
  • Find out if abnormal chromosomes are causing problems having children, including:
    • Male or female infertility
    • Miscarriages, if you have lost two or more pregnancies before 20 weeks
    • Stillbirth
    • Help diagnose and/or make treatment decisions for certain types of cancer and blood disorders

FISH

  • Screening result suggests aneuploidy
  • Advanced maternal age
  • One major or at least two minor fetal structural defects found on ultrasound
  • Previous fetus or child with aneuploidy
  • Parent of this pregnancy has a structural chromosome abnormality (e.g.,translocation, inversion) involving chromosome 18

Test Methods and Limitations

Karyotyping - Chromosomal Analysis / Light Microscopy

FISH - Fluorescence in situ hybridization (FISH) Fluorescence Microscopy

Detailed Sample Requirements

Whole Blood (EDTA)
Test Details Page
Collection Container(s) EDTA (purple top)
Collection Infants (< 2-years): 2 to 3 mL; Children (>2-years): 3 to 5 mL; Older children and adults: Minimum 5mL. The blood tube should be inverted several times immediately after blood collection to prevent coagulation.
Sample Condition Store at ambient temperature. Do not refrigerate or freeze.
Shipping Ship overnight at ambient temperature ensuring receipt within 5-days of collection.
Special Sample Instructions Clotted or hemolyzed samples are not accepted.