Array CGH of the FOXL2 and FOXC1 Regions Involved in BPES and Axenfeld–Rieger Malformations

Abstract

Background: : MLPA and microsatellite analysis recently enabled us to detect submicroscopic deletions either encompassing or located outside the forkhead transcription factor gene FOXL2 (3q23) in families with blepharophimosis syndrome (BPES). These deletions account for 16% of all molecular defects we found in BPES. The extragenic deletions located upstream and downstream of FOXL2 represent a new mutational mechanism for BPES. In addition, we identified 4 deletions encompassing FOXC1 (6p25) in patients with Axenfeld–Rieger malformations using MLPA, confirming that changes in gene dosage of FOXC1 result in anterior segment malformations.

Purpose: : Development of an alternative tool for identification and delineation of submicroscopic genomic rearrangements of the FOXL2 region in BPES patients and of the FOXC1 region in patients with Rieger anomalies.

Patients and Methods: : Two sets of patients were enrolled in this study: (1) sixteen BPES patients and four Rieger patients with a known genomic rearrangement; and (2) twelve BPES patients with a previously unidentified genetic defect. The method of this study is array based comparative genome hybridization (array CGH) using a high–density tiling BAC array of 2.9 Mb and 3.1 Mb for the FOXL2 and FOXC1 regions respectively.

Results: : In the first set of patients we detected and delineated the 16 known FOXL2 related deletions and 4 known FOXC1 deletions in all cases. In the second group of patients one novel extragenic deletion of ∼ 200 kb located upstream of FOXL2 was identified in a sporadic BPES patient.

Conclusions: : In this study we developed and validated a tiling BAC array around FOXL2 and FOXC1. This is an alternative tool for identification and delineation of genomic rearrangements in the two selected regions. Future perspectives include array CGH studies in 70 additional BPES patients and 20 Rieger patients with a previously unidentified mutation. The array will be complemented with additional BAC clones to cover a larger region, and with PCR products to increase the resolution.

Keywords: gene screening • genetics • gene microarray