Name of the Procedure:

Comparative Analysis using Short Tandem Repeat (STR) Markers; Each Additional Specimen Also known as: Additional Specimen STR Analysis, Additional STR DNA Testing

Summary

Comparative analysis using Short Tandem Repeat (STR) markers is a genetic test that examines specific regions in DNA. This test is performed to analyze additional specimens, such as additional cord blood donors, fetal samples from different cultures, or additional zygosity in multiple birth pregnancies.

Purpose

The procedure is used to establish genetic relationships, verify identity, and diagnose certain genetic conditions. The goal is to provide accurate genetic information for medical, forensic, or legal purposes.

Indications

• Verification of genetic relationships (e.g., paternity/maternity testing).
• Zygosity testing in multiple births (identical vs. fraternal twins).
• Genetic compatibility in cord blood donation.
• Additional fetal samples to ensure genetic consistency or diagnose conditions.

Preparation

• No specific preparation is typically required for the patient.
• Collection of samples might need coordination, such as swabbing for cheek cells or collecting blood samples.
• Patients should inform the healthcare provider about any medications they are taking.

Procedure Description

1. Sample Collection: Collect additional specimens (e.g., blood, cheek swabs, or amniotic fluid).
2. DNA Extraction: Isolate DNA from the collected specimens.
3. STR Marker Amplification: Use Polymerase Chain Reaction (PCR) to amplify STR regions in the DNA.
4. Electrophoresis: Separate amplified DNA fragments using gel electrophoresis.
5. Analysis: Compare and analyze the STR marker patterns of the additional specimens against the initial sample.

Tools and Technology Used:

• PCR machines
• Gel electrophoresis apparatus
• DNA extraction kits

Anesthesia or Sedation: Not typically required.

Duration

The entire procedure, including sample collection and analysis, may take several hours to a few days, depending on the specimen type and testing complexity.

Setting

• Hospital laboratories
• Specialized genetic testing facilities
• Outpatient clinic

Personnel

• Geneticists
• Laboratory technicians
• Nurses (for sample collection)

Risks and Complications

• Minor discomfort during sample collection (e.g., blood draw).
• Rare possibilities of sample contamination leading to inconclusive results.

Benefits

• Accurate genetic information for medical, forensic, or legal decisions.
• Peace of mind in verifying genetic relationships or zygosity.
• Timely diagnosis and treatment decisions for certain genetic conditions.

Recovery

• No recovery time is needed as the procedure is non-invasive except for sample collection.
• Normal activities can be resumed immediately.
• Follow-up may include discussing the results with a genetic counselor or healthcare provider.

Alternatives

• Other genetic testing methods (e.g., SNP arrays, whole-genome sequencing) may be used.
• Pros of alternatives may include more extensive genetic information.
• Cons may involve higher cost and longer processing times.

Patient Experience

• During sample collection, patients may feel minor discomfort or, in the case of blood draws, slight pain.
• Post-procedure, patients may experience minimal to no discomfort.
• Results communication and consultation may provide clarity and next steps for the patient.