High resolution chromosome analysis detects:
- Interstitial microdeletions and microduplications greater than 4.0 Mb in size
- Subtle balanced rearrangements
- Partial trisomies
- Partial monosomies
- Marker chromosomes
Follow-up studies, such as chromosomal microarray (CMA) or fluorescence in situ hybridization (FISH), may be recommended if a more subtle chromosomal abnormality is suspected.
Indications for performing high resolution chromosome analysis include:
- Developmental delays
- Growth delay
- Intellectual disability
- Multiple congenital anomalies
- Abnormal phenotype that is not consistent with a particular trisomy or sex chromosome abnormality
- Positive family history for abnormal pregnancy outcome
- Recurrent miscarriage or infertility
- Phenotype suggestive of a particular microdeletion or microduplication syndrome
A minimum of 20 metaphases are examined, with emphasis on specific chromosome sub-band regions at ≥650 band stage of chromosome condensation, and 3 karyotypes are prepared.
Molecular cytogenetic studies using fluorescence in situ hybridization (FISH) are often performed in addition to high resolution studies when a microdeletion syndrome is suspected.
- Submit 3 ml peripheral blood specimen in a 3 cc sodium heparin, green top tube
- Label specimen tube with patient’s name and a second identifier (ex: DOB, hospital ID)
- Maintain specimen at room temperature and transport to the Colorado Genetics Laboratory immediately
Samples must be accompanied by a completed Test Request Form, including pertinent clinical and family history.