Postnatal Chromosome Testing
Chromosome analysis
involves the culturing of living cells. The harvested metaphase cells are stained (G-banding)
and viewed under the microscope for numeric and structural abnormalities. The resolution for chromosome analysis
is about 5-10Mb. The turnaround time is subject to growth variables and complexity of analysis. Results are generally
available in approximately 2-3 weeks. Preliminary results on STAT cases to rule out trisomy are available in 48 hrs
and are finalized within 7 days. Microscopic examination of both chromosome number and structure is performed.
Examination of 20 metaphases is routinely performed and additional metaphases will be studied when indicated. At least
5 cells are fully analyzed with 3 or more G-banded karyograms created by computer image analysis on each patient.
Chromosome Analysis Options
- Routine and stat peripheral blood chromosome analyses
- High resolution peripheral blood chromosome analysis
- Mosaicism study to rule out mosaic aneuploidy
- Newborn cord blood chromosome analysis
- 5-cell analysis in conjunction with microarray analysis
Chromosome analysis is the first line test for the following conditions:
- Patient with suspected aneuploidy (Trisomy 13, Trisomy 18, Trisomy 21 or Down syndrome, Turner syndrome, Klinefelter syndrome)
- Phenotypically normal individual with (or partner with) repeated pregnancy losses
- Family history of chromosome rearrangement
Specimen Requirements
| Postnatal And Adult Karyotyping And Fish | ||
| Specimen Types | Requirements | Turnaround Times |
| Peripheral Blood |
1 green top tube (sodium heparin) containing 5 cc whole blood For infant or young children: 1 green top tube (sodium heparin) containing 1-3 cc whole blood If CGH testing is anticipated later 1 purple top tube (EDTA) containing 5cc whole blood is requested |
2-3 weeks for routine cases 48 hr. verbal preliminary results on STAT analyses; 7 day final report on STAT analyses. |
| Postnatal And Adult (CGH Or CGH+SNP, FISH And KARYOTYPING) | ||
| Specimen Types | Requirements | Turnaround Times | Peripheral Blood |
1 green top tube (sodium heparin) and one purple top tube (EDTA), each containing 5 cc whole blood For infants or young children: 1 green top tube (sodium heparin) and one purple top tube (EDTA) , each containing 1-3 cc whole blood |
Requirements Document and Requisition Form
Use Adobe Acrobat to print the PDF forms.
Advantages And Limitations
- Conventional cytogenetic analysis is capable of detecting structural and numeric chromosomal abnormalities in postnatal samples with a resolution of 5-10 Mb (575 G-banded level for routine cases and 650 G-banded level or higher for high resolution cases).
- Cryptic submicroscopic microdeletions and microduplications cannot be detected by conventional chromosome analysis.
- Conventional cytogenetic analysis requires cell cultures for metaphase preparations.
Postnatal Chromosome Testing
Chromosome analysis involves the culturing of living cells. The harvested metaphase cells are stained (G-banding) and viewed under the microscope for numeric and structural abnormalities. The resolution for chromosome analysis is about 5-10Mb. The turnaround time is subject to growth variables and complexity of analysis. Results are generally available in approximately 2-3 weeks. Preliminary results on STAT cases to rule out trisomy are available in 48 hrs and are finalized within 7 days. Microscopic examination of both chromosome number and structure is performed. Examination of 20 metaphases is routinely performed and additional metaphases will be studied when indicated. At least 5 cells are fully analyzed with 3 or more G-banded karyograms created by computer image analysis on each patient.
Chromosome Analysis Options
- Routine and stat peripheral blood chromosome analyses
- High resolution peripheral blood chromosome analysis
- Mosaicism study to rule out mosaic aneuploidy
- Newborn cord blood chromosome analysis
- 5-cell analysis in conjunction with microarray analysis
Chromosome analysis is the first line test for the following conditions:
- Patient with suspected aneuploidy (Trisomy 13, Trisomy 18, Trisomy 21 or Down syndrome, Turner syndrome, Klinefelter syndrome)
- Phenotypically normal individual with (or partner with) repeated pregnancy losses
- Family history of chromosome rearrangement
Specimen Requirements
| Postnatal And Adult Karyotyping And Fish | ||
| Specimen Types | Requirements | Turnaround Times |
| Peripheral Blood |
1 green top tube (sodium heparin) containing 5 cc whole blood For infant or young children: 1 green top tube (sodium heparin) containing 1-3 cc whole blood If CGH testing is anticipated later 1 purple top tube (EDTA) containing 5cc whole blood is requested |
2-3 weeks for routine cases 48 hr. verbal preliminary results on STAT analyses; 7 day final report on STAT analyses. |
| Postnatal And Adult (CGH Or CGH+SNP, FISH And KARYOTYPING) | ||
| Specimen Types | Requirements | Turnaround Times | Peripheral Blood |
1 green top tube (sodium heparin) and one purple top tube (EDTA), each containing 5 cc whole blood For infants or young children: 1 green top tube (sodium heparin) and one purple top tube (EDTA) , each containing 1-3 cc whole blood |
Requirements Document and Requisition Form
Use Adobe Acrobat to print the PDF forms.
Advantages And Limitations
- Conventional cytogenetic analysis is capable of detecting structural and numeric chromosomal abnormalities in postnatal samples with a resolution of 5-10 Mb (575 G-banded level for routine cases and 650 G-banded level or higher for high resolution cases).
- Cryptic submicroscopic microdeletions and microduplications cannot be detected by conventional chromosome analysis.
- Conventional cytogenetic analysis requires cell cultures for metaphase preparations.