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W Bao, GK Klintworth; A Spontaneous Mutation (R124H) in the TGFBI Gene in a Sporadic Case of Granular Corneal Dystrophy Type II . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1738.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the human transforming growth factor beta-induced gene (TGFBI, also known as BIGH3) for mutations in a patient, who was diagnosed as having granular corneal dystrophy (GCD), but who had a negative family history of corneal disease. Methods: Several ophthalmologists with expertise in corneal disease made the diagnosis clinically. Genomic DNA was extracted from the blood of the patient as well as from the clinically unaffected parents and child of the patient. Exons 4 and 12 of the TGFBI gene, which are mutated in different variants of GCD were amplified by the polymerase chain reaction (PCR). The exons were evaluated for mutations using Denaturing High Performance Liquid Chromatography (DHPLC) and DNA sequencing. Specimens of DNA derived from the blood and both alleged parents were screened with 9 sets of markers that are routinely used in medicolegal paternity testing. This was done because the importance of confirming the biological parents of the patient. Results: The patient was found to have a heterozygous missense R124H mutation in exon 4 of the TGFBI gene, but no mutation in exon 12 of this gene. No mutations were found in either of these exons in the parents or the child. The genetic analysis of the patient and the parents indicated that the putative parents were indeed the biological parents. Conclusion: This is the first case report of a spontaneous mutation in the TGFBI gene causing GCD. This study further confirms that a mutation in TGFBI is responsible for GCD. The mutation (R124H) and the clinical findings are consistent with other cases of GCD type II.
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