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Genotype-Phenotype Correlation in 2 Indian Families With Severe Granular Corneal Dystrophy
Chitra Kannabiran, PhD;
Mittanamalli S. Sridhar, MD;
S. Kalyana Chakravarthi, MSc;
Geeta K. Vemuganti, MD;
Meena Lakshmipathi, MD
Arch Ophthalmol. 2005;123:1127-1133.
Objectives To determine genotypes in 2 Indian families with severe granular corneal dystrophy, to document clinical and histopathologic features, and to attempt a genotype-phenotype correlation.
Methods Mutation analysis of exon 12 of the TGFBI gene was carried out in 9 individuals from 2 families.
Results A C T mutation at residue 1710 of TGFBI complementary DNA, corresponding to an Arg555Trp mutation in keratoepithelin, was found in affected members of both families. In 5 patients, this mutation was homozygous, and it was heterozygous in the other 4. Clinical examination revealed a severe form of granular corneal dystrophy with early onset and superficial lesions in the homozygous individuals and a milder phenotype in the heterozygous individuals. Histopathologic evaluation of corneal specimens from 2 homozygous patients confirmed the presence of superficial granular deposits.
Conclusions To our knowledge, this is the first molecular and clinical characterization of severe granular corneal dystrophy in India. Genotype-phenotype correlation and comparison with earlier reports on this entity highlight the uniform expressivity of the Arg555Trp allele in homozygous individuals.
Clinical Relevance Homozygous granular corneal dystrophy has a severe phenotype and can be recognized based on clinical and histopathologic features, especially in association with consanguinity or inbreeding.
Author Affiliations: Kallam Anji Reddy Molecular Genetics Laboratory (Dr Kannabiran and Mr Chakravarthi) and Ophthalmic Pathology Service (Dr Vemuganti), Professor Brien Holden Eye Research Centre, and Cornea and Anterior Segment Service (Drs Sridhar and Lakshmipathi), L. V. Prasad Eye Institute, Hyderabad, India.
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