Gamma-Globin Full Gene Sequencing

Casandra

Casandra Test Code MC89179Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID WGSEQCPT Code 81479

Gamma-Globin Full Gene Sequencing

Clinical Use

Use

This test is useful as an adjunct to abnormal results detected by hemoglobin electrophoresis testing. It assists in the diagnosis of nondeletional hereditary persistence of fetal hemoglobin (HPFH), identification of abnormal gamma chain variants such as unstable, high- or low-oxygen affinity, or M hemoglobins, and predicting the severity of a coinherited sickling disorder. It is also relevant for evaluating unexplained neonatal anemia, cyanosis, or hyperbilirubinemia.

Special Instructions

A complete patient history is strongly encouraged. New York clients must provide informed consent, documented on the request form or electronic order. Special documentation is required for New York clients, and a benign hematology test request form is needed if not ordering electronically.

Limitations

This test cannot be used in isolation to confirm or exclude hemoglobin conditions. Large deletions, crossover events, or other variants may not be detected, and sequencing cannot distinguish between alleles in cis or trans. Molecular results should be correlated with electrophoretic, protein data, and/or family studies for accurate diagnosis.

Test Details

New York Approved

Methodology

PCR-based (Sanger)

Biomarkers

Total genomic DNA is extracted from the sample, and the full gamma globin genes are amplified by polymerase chain reaction in separate reactions followed by Sanger sequencing. Automated calls and manual reviews are performed on sequence data.