Abstract
Macular Telangiectasia type 2 (MacTel) is a relatively rare macular disease of adult onset presenting with distortions in the visual field and leading to progressive loss of visual acuity. For the purpose of a gene mapping study, several pedigrees were ascertained with multiple affected family members. Seventeen families with a total of 71 individuals (including 45 affected or possibly affected) were recruited at clinical centers in 7 countries under the auspices of the MacTel Project. The disease inheritance was consistent with autosomal dominant segregation with reduced penetrance. Genome-wide linkage analysis was performed, followed by analysis of recombination breakpoints. Linkage analysis identified a single peak with multi-point LOD score of 3.45 on chromosome 1 at 1q41-42 under a dominant model. Recombination mapping defined a minimal candidate region of 15.6 Mb, from 214.32 (rs1579634; 219.96 cM) to 229.92 Mb (rs7542797; 235.07 cM), encompassing the 1q41-42 linkage peak. Sanger sequencing of the top 14 positional candidates genes under the linkage peak revealed no causal variants in these pedigrees.
Highlights
Macular telangiectasia is a group of diseases characterized by Gass and Blodi in 1993 [1] and reclassified by Yannuzzi in 2006 [2]
Variable disease expressivity is evident in many pedigrees in this cohort; while probands presented to the clinic experiencing vision loss, some relatives were given a diagnosis of Macular telangiectasia type 2 (MacTel) only after a complete ophthalmic exam as a part of this study
This study presents the first genome-wide linkage analysis of MacTel
Summary
Macular telangiectasia is a group of diseases characterized by Gass and Blodi in 1993 [1] and reclassified by Yannuzzi in 2006 [2]. Macular telangiectasia type 2 (MacTel) generally presents bilaterally between the 5th and 7th decades of life with reduction in central vision and distortion in the visual field. Clinical characteristics of MacTel include loss of retinal transparency, autofluorescence changes in the macula, macular edema, presence of intraretinal crystals, and disruption of macular pigment transport. Symptoms of advanced disease include the presence of a macular hole, dilated and tortuous vessels in the perifoveal region, leakage from retinal vessels and neovascularization arising from the intraretinal vessels [3,4,5,6,7,8,9,10,11,12]. Patients experience distortions in central vision, including parafoveal scotoma, and metamorphopsia.
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