RESUMEN
BACKGROUND: The genetic basis of X-linked megalocornea (MGC1) was reported in 2012 to be caused by mutations in the CHRDL1 gene. We sought to confirm that mutations in CHRDL1 are associated with MGC1 in a previously unreported pedigree. MATERIALS AND METHODS: Slit lamp examination, corneal pachymetry, corneal topography and DNA collection for screening of the CHRDL1 gene were performed for members of an affected family. RESULTS: Examination of a woman and her four sons, ranging in age between 3 and 15 years, demonstrated horizontal corneal diameters of 14 mm in three of the four sons and a normal corneal diameter of 12 mm in the mother and other son. Central corneal thickness in the individuals with enlarged corneal diameters averaged 474 microns, compared to 604 microns in their unaffected brother. Corneal topographic imaging demonstrated an average K value of 44.4 D in the affected individuals compared with 41.6 D in their unaffected sibling. Screening of the CHRDL1 gene demonstrated the novel hemizygous frameshift mutation c.167delC (p.(Pro56Leu*8)) in exon 3 in the affected individuals and in the heterozygous state in their mother. This mutation was not present in the unaffected brother or in unrelated controls. CONCLUSION: We provide the initial confirmation that X-linked megalocornea is associated with mutations in the CHRDL1 gene.
Asunto(s)
Córnea/patología , Enfermedades Hereditarias del Ojo/genética , Proteínas del Ojo/genética , Mutación del Sistema de Lectura , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Proteínas del Tejido Nervioso/genética , Adolescente , Adulto , Niño , Preescolar , Paquimetría Corneal , Topografía de la Córnea , Exones/genética , Enfermedades Hereditarias del Ojo/diagnóstico , Femenino , Amplificación de Genes , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico , Humanos , Masculino , Linaje , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADNRESUMEN
PURPOSE: To retrospectively analyze the potential sources of error for IOL power calculation in patients with X-linked related megalocornea (XLMC). METHODS: Case report and comparative analysis of refractive outcomes in previously reported phacoemulsification procedures in XLMC cases. RESULTS: A 52-year-old patient with XLMC and cataracts underwent bilateral clear corneal phacoemulsification, capsule tension ring (CTR) insertion, and in the bag intraocular lens (IOL) implantation. Two years after the procedure the IOL remained centrally located and stable in both eyes. In the postoperative refraction, the patient had a large hyperopic refractive error in the right eye, and a moderate hyperopic refractive error in the left eye. A similar pattern was observed in previously reported cases. Pooling all cases together we observed that the Holladay II formula produced more accurate IOL power calculations than the SRK-T formula. Still, both formulas diverged from the ideal IOL power by approximately 1 diopter per mm of axial length in subjects with axial lengths larger than 24 mm. CONCLUSION: Axial length seems to be the main source of IOL power calculation error in XLMC patients. Compared to SRK-T the Holladay II formula provides better refractive results, yet both formulas may require further adjustment depending on the axial length.