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Test Code Test Name Turnaround Blood Sample Tissue Sample CPT Codes 2015 CPT Codes 2013
8003 VSX1 (Visual System Homeobox 1) 3 weeks $800.00 $900.00 81404 81479

Selecting the Appropriate Sample Type


Keratoconus is a corneal disease that results in thinning of the cornea which leads to a cone-shaped steepening instead of the gradual, flattened curvature of the normal cornea. Patients with keratoconus often complain of distorted vision and light sensitivity. Most keratoconus patients are diagnosed during their teenage years by their eye care professionals. Vision changes caused by keratoconus may affect patients’ abilities to drive or read. This condition could be caused by mutations in the VSX1 gene [1, 2].

The VSX1 gene encodes a pair-like homeodomain and regulates many genes’ expression in the eyes[3]. Mutations of this gene can cause keratoconus and posterior polymorphous corneal dystrophy [2], another type of corneal dystrophy. In this test, genomic DNA will be purified from a biological sample and used for PCR. 6 sets of exon-specific primers will be used to amplify the exons and the exon-intron junctions for this gene.


1. Bisceglia, L., et al., VSX1 mutational analysis in a series of Italian patients affected by keratoconus: detection of a novel mutation. Invest Ophthalmol Vis Sci, 2005. 46(1): p. 39-45. 

2. Heon, E., et al., VSX1: a gene for posterior polymorphous dystrophy and keratoconus. Hum Mol Genet, 2002. 11(9): p. 1029-36.

3. Semina, E.V., H.A. Mintz-Hittner, and J.C. Murray, Isolation and characterization of a novel human paired-like homeodomain-containing transcription factor gene, VSX1, expressed in ocular tissues. Genomics, 2000. 63(2): p. 289-93