Name of the Procedure:

Molecular cytogenetics; chromosomal in situ hybridization, analyze 10-30 cells (e.g., for microdeletions)

Summary

This procedure uses a technique called chromosomal in situ hybridization (CISH) to examine 10-30 cells and identify chromosomal abnormalities, such as microdeletions. It involves using fluorescent probes to bind to specific DNA sequences on chromosomes, which allows for visualization under a fluorescence microscope.

Purpose

The purpose of this procedure is to diagnose or rule out genetic conditions caused by small chromosomal deletions (microdeletions). It helps in identifying specific genetic abnormalities that may be causing developmental delays, congenital anomalies, or other medical conditions.

Indications

• Unexplained developmental delays or intellectual disabilities
• Congenital anomalies or birth defects
• Family history of genetic conditions known to involve microdeletions
• Screening for prenatal genetic abnormalities
• Unexplained recurrent miscarriages

Preparation

• No special preparation such as fasting is usually required.
• Patients may need to provide a blood sample or a sample from another tissue.
• Discuss current medications with the doctor as certain ones might need to be adjusted.

Procedure Description

1. A sample is collected from the patient, usually blood or tissue.
2. The cells from the sample are cultured and prepared on slides.
3. Fluorescent probes specific to the target DNA sequences are applied to the slides.
4. The slides are then incubated to allow the probes to bind to their target sequences.
5. After incubation, the slides are washed and analyzed under a fluorescence microscope.
6. The binding patterns of the probes are examined to detect any chromosomal abnormalities.

Tools and Equipment Used:

• Fluorescence microscope
• Fluorescent DNA probes
• Incubators
• Microtome (if tissue samples are used)

Anesthesia or Sedation:

• Typically not required, as the procedure involves only sample collection and laboratory analysis.

Duration

The entire process, from sample collection to analysis, typically takes a few days to a week, but the actual analysis may only take a few hours.

Setting

• Laboratory
• Hospital or specialized genetic clinic

Personnel

• Medical geneticist or cytogeneticist
• Laboratory technicians
• Pathologists (if tissue samples are involved)

Risks and Complications

Common Risks:

• Discomfort from sample collection (e.g., blood draw)

Rare Risks:

• Misdiagnosis due to technical errors

Possible Complications:

• Contamination or inadequate sample, requiring re-sampling

Benefits

• Accurate diagnosis of genetic conditions.
• Informative for making medical and personal decisions.
• Helps in early intervention and management of identified conditions.

Recovery

• Minimal post-procedure recovery required.
• Normal activities can be resumed immediately after sample collection.
• Follow-up appointments may be scheduled to discuss results.

Alternatives

• Array Comparative Genomic Hybridization (aCGH)
• Quantitative PCR
• Whole genome sequencing

Pros and Cons of Alternatives:

• aCGH provides a broader analysis but can be more expensive and complex.
• Quantitative PCR is quicker but may not cover all possible microdeletions.
• Whole genome sequencing offers detailed information but is costlier and more time-consuming.

Patient Experience

During Sample Collection:

• Mild discomfort or pain during blood draw or tissue sampling

After Procedure:

• No significant discomfort
• Mild soreness at the sample collection site, if applicable

Pain Management and Comfort Measures:

• Use of a topical anesthetic cream for sample collection, if necessary
• Post-collection care instructions, like applying a cold pack to the site if needed.