A clinical and molecular genetic study of a rare dominantly inherited syndrome (MRCS) comprising of microcornea, rod-cone dystrophy, cataract, and posterior staphyloma
- M A Reddy1,
- P J Francis2,
- V Berry1,
- K Bradshaw3,
- R J Patel1,
- E R Maher4,
- R Kumar5,
- S S Bhattacharya1,
- A T Moore1
- 1Institute of Ophthalmology, London, UK
- 2Moorfields Eye Hospital, London, UK
- 3Addenbrooke’s Hospital, Cambridge, UK
- 4Medical and Molecular Genetics Section, University of Birmingham, Birmingham, UK
- 5George Eliot Hospital, Nuneaton, UK
- Correspondence to: M A Reddy, Institute of Ophthalmology, London, UK; mareddy{at}doctors.org.uk
- Accepted 9 September 2002
Abstract
Aim: To phenotype and genetically map the disease locus in a family presenting with autosomal dominant microcornea, rod-cone dystrophy, cataract, and posterior staphyloma.
Methods: Six affected and three unaffected members of the pedigree were examined. All individuals provided a history and underwent a full clinical examination with A-scan and B-scan ultrasonography and electrophysiological testing where appropriate. PCR based microsatellite marker genotyping using a positional candidate gene approach was then performed on DNA samples extracted from venous blood provided by each subject.
Results: The disorder is inherited as an autosomal dominant trait with variable expressivity and has a complex phenotype. Affected individuals had bilateral microcornea, pulverulent-like lens opacities, a rod-cone dystrophy and posterior staphyloma (MRCS). Using a positional candidate gene approach, the authors have evidence suggestive of linkage of this disorder to a region on 11q13 within the nanophthalmos 1 (NNO1) genetic interval. The small family size militates against achieving a LOD score of 3, but the haplotype data and the position of the putative MRCS locus within a known nanophthalmos locus are suggestive of linkage. A candidate gene within this region (ROM1) was screened and no mutations were found in affected members of the family.
Conclusion: This rare developmental disorder has some phenotypic similarities to nanophthalmos and possibly maps to a locus within the genetic interval encompassing the NNO1 locus. Screening of candidate genes within this region continues.
