Recessive Congenital Methemoglobinemia, CYB5 and CYB5 Reductase Genetic Analysis, Next-Generation Sequencing

Casandra

Casandra Test Code MC34090Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID NCYBCPT Code 81479

Recessive Congenital Methemoglobinemia, CYB5 and CYB5 Reductase Genetic Analysis, Next-Generation Sequencing

Clinical Use

Use

This test provides a genetic evaluation for patients with a personal or family history suggestive of recessive congenital methemoglobinemia. It offers genotype confirmation of borderline cytochrome b5 reductase (methemoglobin reductase: METR) enzyme activity levels and identifies variants within the CYB5 and CYB5 reductase genes (_CYB5A_, _CYB5R3_) for further genetic counseling. The identification of a disease-causing variant can aid in diagnosis, prognosis, clinical management, recurrence risk assessment, familial screening, and genetic counseling for congenital methemoglobinemia.

Special Instructions

This test should be performed after more common causes of methemoglobinemia have been eliminated. It is best interpreted in conjunction with protein functional findings by enzymatic assay and complete blood cell count analysis. Additional information such as clinical diagnosis and pertinent clinical history should accompany the test request to ensure accurate interpretation.

Limitations

Next-generation sequencing may not detect all types of genomic variants, with false-negative or false-positive results occurring rarely. Some regions, due to technical limitations like homology or GC content, might not be effectively evaluated. High coverage or test failures below the minimum acceptable criteria will be noted. Variants may not be determined if coverage is below standard thresholds, affecting the ability to accurately detect certain deletions or duplications. This test is not designed to detect low levels of mosaicism or differentiate between somatic and germline variants, which may necessitate additional testing.

Test Details

New York Approved