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Phenotype of autosomal recessive congenital microphthalmia mapping to chromosome 14q32
D A Bessant1, K Anwar, S Khaliq
1Department of Molecular Genetics, Institute of Ophthalmology, London.
Background:
Congenital microphthalmia (OMIM: 309700) may occur in isolation or in association with a variety of systemic malformations. Isolated microphthalmia may be inherited as an autosomal dominant, an autosomal recessive, or an X linked trait.
Methods:
Based on a whole genome linkage analysis, in a six generation consanguineous family with autosomal recessive inheritance, the first locus for isolated microphthalmia was mapped to chromosome 14q32. Eight members of this family underwent clinical examination to determine the nature of the microphthalmia phenotype associated with this locus.
Results:
All affected individuals in this family suffered from bilateral microphthalmia in association with anterior segment abnormalities, and the best visual acuity achieved was "perception of light". Corneal changes included partial or complete congenital sclerocornea, and the later development of corneal vascularisation and anterior staphyloma. Intraocular pressure, as measured by Schiotz tonometry, was greatly elevated in many cases.
Conclusions:
This combination of ocular defects suggests an embryological disorder involving tissues derived from both the neuroectoderm and neural crest. Other families with defects in the microphthalmia gene located on 14q32 may have a similar ocular phenotype aiding their identification.
Insights
Researchers identified the first gene locus for isolated microphthalmia on chromosome 14q32. This finding aids in diagnosing congenital microphthalmia, a severe bilateral eye abnormality.
Area of Science:
- Ophthalmology
- Genetics
- Developmental Biology
Background:
- Congenital microphthalmia can be isolated or part of systemic malformations.
- Inheritance patterns include autosomal dominant, autosomal recessive, and X-linked traits.
Purpose of the Study:
- To map the genetic locus for isolated microphthalmia in a consanguineous family.
- To characterize the ocular phenotype associated with the identified locus.
Main Methods:
- Whole genome linkage analysis was performed on a six-generation consanguineous family.
- Clinical examination of eight affected family members determined the microphthalmia phenotype.
Main Results:
- The first locus for isolated microphthalmia was mapped to chromosome 14q32.
- Affected individuals presented with bilateral microphthalmia and anterior segment abnormalities.
- Corneal changes included sclerocornea, vascularization, and anterior staphyloma, with elevated intraocular pressure in many cases.
Conclusions:
- The observed ocular defects suggest an embryological disorder involving neuroectoderm and neural crest tissues.
- Identification of the 14q32 microphthalmia gene aids in diagnosing similar phenotypes in other families.