The Invitae Choroideremia Test analyzes the CHM gene, which is associated with choroideremia, a disorder that is characterized by chorioretinal degeneration. This gene is the only gene currently known to cause choroideremia.
Genetic testing of this gene may confirm a diagnosis and help determine prognosis. Identification of a disease-causing variant can inform recurrence-risk and genetic counseling.
Choroideremia is characterized by progressive loss of vision in males with onset of night blindness in early childhood, followed by loss of peripheral vision and a loss of visual acuity later in life. This loss in vision is caused by progressive chorioretinal degeneration. Carrier females are generally asymptomatic, although some signs of chorioretinal degeneration have been observed. Carrier females may develop night blindness and visual field loss later in life.
Sequencing and duplication/deletion analysis of the CHM gene identifies causative variants in approximately 78% to 95% of individuals with suspected or confirmed choroideremia.
Choroideremia is inherited in an X-linked manner.
Complete penetrance is expected in males. Carrier females are generally asymptomatic, although some signs of chorioretinal degeneration have been observed. Carrier females may develop night blindness and visual field loss later in life.
Choroideremia occurs in an estimated 1 in 50,000 – 100,000 individuals.
Testing may be considered for individuals with a fundus examination consistent with choroideremia.
Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).
Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence, and select noncoding variants. Our assay provides a Q30 quality-adjusted mean coverage depth of 350x (50x minimum, or supplemented with additional analysis). Variants classified as pathogenic or likely pathogenic are confirmed with orthogonal methods, except individual variants that have high quality scores and previously validated in at least ten unrelated samples.
Our analysis detects most intragenic deletions and duplications at single exon resolution. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. If you are requesting the detection of a specific single-exon copy number variation, please contact Client Services before placing your order.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|