The Invitae Early-Onset Glaucoma Panel analyzes three genes that are associated with early-onset glaucoma. Genetic testing of these genes may help confirm a clinical diagnosis and provide information for recurrence-risk estimation and genetic counseling.
CYP1B1 FOXC1 PITX2
CYP1B1 FOXC1 PITX2
Primary congenital glaucoma (PCG) is an early-onset form of glaucoma that typically affects both eyes, causes reduced visual acuity and restricted visual fields, and leads to blindness if untreated. PCG often presents with cloudiness of the cornea and buphthalmos; other common findings include increased intraocular pressure, progressive glaucomatous optic atrophy, thinning of the anterior sclera, edema, iris atrophy, and an unusually deep anterior chamber. Epiphora, photophobia, and blepharospasm are frequent symptoms. Classic PCG does not include structural defects of the anterior chamber that are found with anterior segment dysgenesis. Most commonly, PCG is diagnosed within the first year of life. Pathogenic changes in CYP1B1 are known to cause PCG and can also be found in individuals with Peters anomaly, juvenile open-angle glaucoma, and primary open-angle glaucoma.
Axenfeld-Rieger syndrome (ARS) refers to overlapping heterogeneous disorders that are primarily characterized by an ophthalmological abnormality but can also include comorbidities such as dysmorphic facial features, abnormal dentition, and, less commonly, heart defects, hearing loss, and pituitary function-related delayed growth. Nearly half of affected individuals develop glaucoma, which can be early-onset. Abnormal development of the anterior segment of the eye manifests as iris hypoplasia or corectopia and anteriorly displaced Schwalbe’s line with iridocorneal adhesions. Affected individuals may exhibit different degrees of abnormality in each eye.
Pathogenic changes in CYP1B1 account for 20-100% of cases of familial PCG and 10-27% of cases of simplex PCG. Whether a molecular diagnosis will be obtained through testing of CYP1B1 varies greatly and depends on the characteristics of the individual tested. The likelihood of identifying pathogenic changes in CYP1B1 increases when an individual is bilaterally affected and has a family history of PCG, known parental consanguinity, and/or severe disease.
Pathogenic changes in FOXC1 and PITX2 account for 15-40% of ARS cases. Approximately half of individuals with ARS develop glaucoma.
Primary congenital glaucoma is inherited in an autosomal recessive manner, and Axenfeld-Rieger syndrome is inherited in an autosomal dominant manner.
Penetrance of glaucoma (primary congenital, juvenile open-angle, or primary open-angle) is about 90% in individuals with pathogenic variants in CYP1B1. ARS is a completely penetrant disorder with approximately half of affected individuals developing glaucoma.
The incidence of PCG is estimated to be between 1:10,000 and 1:70,000 in the United States and Western European countries. In specific populations (including the Middle East and a part of India), the incidence can be as high as between 1:1,250 and 1:3,300.
The prevalence of Axenfeld-Rieger syndrome is estimated at 1 in 200,000 individuals, with approximately half of affected individuals developing glaucoma.
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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 in the transcript listed below. In addition, analysis covers the select non-coding variants specifically defined in the table below. Any variants that fall outside these regions are not analyzed. Any specific limitations in the analysis of these genes are also listed in the table below.
Based on validation study results, this assay achieves >99% analytical sensitivity and specificity for single nucleotide variants, insertions and deletions <15bp in length, and exon-level deletions and duplications. Invitae's methods also detect insertions and deletions larger than 15bp but smaller than a full exon but sensitivity for these may be marginally reduced. Invitae’s deletion/duplication analysis determines copy number at a single exon resolution at virtually all targeted exons. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. Certain types of variants, such as structural rearrangements (e.g. inversions, gene conversion events, translocations, etc.) or variants embedded in sequence with complex architecture (e.g. short tandem repeats or segmental duplications), may not be detected. Additionally, it may not be possible to fully resolve certain details about variants, such as mosaicism, phasing, or mapping ambiguity. Unless explicitly guaranteed, sequence changes in the promoter, non-coding exons, and other non-coding regions are not covered by this assay. Please consult the test definition on our website for details regarding regions or types of variants that are covered or excluded for this test. This report reflects the analysis of an extracted genomic DNA sample. In very rare cases, (circulating hematolymphoid neoplasm, bone marrow transplant, recent blood transfusion) the analyzed DNA may not represent the patient's constitutional genome.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|