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A new genetic locus for X linked progressive cone-rod dystrophy
R Jalkanen1, F Y Demirci, H Tyynismaa
1Department of Obstetrics and Gynaecology, Helsinki University Central Hospital, Helsinki, Finland.
Journal of Medical Genetics
|June 17, 2003
Summary
Researchers identified a new genetic locus for X-linked progressive cone-rod dystrophy (COD) in a Finnish family. This discovery expands the understanding of genetic heterogeneity in this vision-impairing retinal disease.
Area of Science:
- Genetics
- Ophthalmology
- Molecular Biology
Background:
- X-linked progressive cone-rod dystrophy (COD) is a retinal disease affecting cone photoreceptors.
- Genetic heterogeneity is known, with two loci (COD1 and COD2) previously identified.
- COD1 is associated with RPGR exon ORF15 mutations, also causing RP3 retinitis pigmentosa.
Purpose of the Study:
- To map the disease gene in a large Finnish family with X-linked COD.
- To investigate genetic heterogeneity in X-linked COD.
Main Methods:
- Linkage analysis using 39 X chromosomal markers.
- Exclusion of COD1 and COD2 loci through recombination analysis and lod score calculations.
- Direct PCR sequencing of the RPGR gene coding region.
Main Results:
- COD1 locus excluded due to recombinations in the Xp21.1-p11.4 region.
- No RPGR mutations found, excluding COD1.
- COD2 locus excluded based on negative lod scores.
- The disease gene localized to Xp11.4-q13.1 between markers DXS10042 and DXS8060.
- Positive lod scores obtained for markers DXS993, MAOB, DXS1055, and DXS1194.
Conclusions:
- A new, third genetic locus for X-linked progressive cone-rod dystrophy has been established.
- This finding contributes to understanding the genetic heterogeneity of COD.
- The identified locus is distinct from previously known COD1 and COD2 loci.
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