81228 Cytogenomic constitutional (genome-wide) microarray analysis; interrogation of genomic regions for copy number variants (eg, bacterial artificial chromosome [BAC] or oligo-based comparative genomic hybridization [CGH] microarray analysis)

Name of the Procedure:

Cytogenomic Constitutional (Genome-Wide) Microarray Analysis; also known as BAC or Oligo-based Comparative Genomic Hybridization (CGH) Microarray Analysis

Summary

This procedure is a laboratory test used to detect variations in chromosome structure, such as deletions or duplications of genetic material. It involves examining the entire genome for abnormalities that may cause genetic disorders or diseases.

Purpose

The purpose of this test is to identify copy number variants (CNVs) in the genome. These variations can be associated with a wide range of genetic disorders, developmental delays, intellectual disabilities, and congenital anomalies. The goal is to diagnose these conditions accurately and help guide appropriate treatment and management.

Indications

• Unexplained developmental delay or intellectual disability
• Autism spectrum disorders
• Congenital anomalies (birth defects)
• Multiple miscarriages
• Family history of genetic disorders
• Individuals with unexplained physical differences or health issues

Preparation

• No specific fasting or dietary restrictions required.
• Patients may be advised to bring relevant medical history, especially family history of genetic disorders.
• Informed consent is required.

Procedure Description

1. A blood sample or, less commonly, a sample of other tissue (such as amniotic fluid) is collected from the patient.
2. DNA is extracted from the sample.
3. The DNA is then labeled with fluorescent dyes and applied to a microarray chip containing thousands of DNA probes.
4. The patient's DNA is hybridized (attached) to the microarray, where DNA from the sample binds to complementary sequences on the chip.
5. The microarray is scanned to detect areas of increased or decreased fluorescence, indicating CNVs.
6. Data is analyzed to determine which regions of the genome have abnormal copy numbers.

Tools and equipment used include microarray chips, fluorescence scanners, and computational software for data analysis. Typically, no anesthesia or sedation is needed.

Duration

The entire process, from sample collection to obtaining results, may take several days to a few weeks, though the actual laboratory testing typically only takes a few hours.

Setting

The procedure is performed in a specialized genetic testing laboratory.

Personnel

• Geneticist
• Laboratory technician
• Genetic counselor (for pre- and post-test counseling)

Risks and Complications

• Very low risk associated with blood sample collection, such as bruising or infection.
• Potential for anxiety or emotional distress based on test results.

Benefits

• Accurate diagnosis of genetic conditions.
• Information gained can guide personalized treatment and management plans.
• Can provide valuable information for family planning.

Recovery

• No physical recovery needed from the procedure itself.
• Follow-up appointment with a genetic counselor to discuss results and next steps.

Alternatives

• Karyotyping: A less sensitive test that examines chromosomes under a microscope.
• Whole Genome Sequencing (WGS): More comprehensive but also more expensive and intensive than CGH microarray.
• Fluorescence In Situ Hybridization (FISH): Used for specific, targeted regions rather than a whole-genome approach. Each alternative has its own pros and cons related to sensitivity, cost, and scope.

Patient Experience

• Blood sample collection is typically quick and causes minimal discomfort.
• Waiting for results might be anxiety-inducing.
• Post-test counseling helps in understanding results and deciding on further steps.

Pain management and comfort measures involve standard blood draw practices such as using topical anesthetics if necessary and ensuring patient comfort during the sample collection.