EPOS

European Paediatric Ophthalmological Society

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Familial inherited microtia, ocular colobomas and imperforation of the nasolacrimal ducts with abnormal chromosome condensation on chromosome 4p16.1

I. Casteels ¹, JR. Vermeesch², G. Matthijs², K. Devriendt^2
1Department of Ophthalmology, University Hospitals Leuven Belgium, ²Department of Human Genetics, University Hospitals Leuven Belgium

Purpose: To describe the clinical and chromosomal findings in a three generation family with different malformations of the branchial arches. Methods: A clinical and ophthalmological examination was performed in the proband, his sister and her son. Cytogenetic and FISH analysis on chromosomal material of the proband was carried out. Results: In this three generation family the combination of microtia, imperforated nasolacrimal ducts and colobomas was inherited in an autosomal dominant way. The finding of iris and chorioretinal colobomas was not present in all members of this family. High resolution cytogenetic analysis revealed an aberrant chromosome 4pter initially in 2 affected family members, and subsequent linkage analysis confirmed linkage of the phenotype to chromosome 4p16. A structural anomaly of this chromosomal region, e.g. deletion or duplication could be excluded. However, the FISH signal intensity at chromosome 4p16.1 was found to be consistently brighter on the aberrant chromosome 4. Conclusion: A new syndrome with autosomal dominant inherited microtia, ocular colobomas and imperforated nasolacrimal ducts is described. We hypothesize that the aberrant FISH staining pattern is due to a local alteration of the chromatin condensation, which, in turn, may have lead to altered gene expression causing the abnormal phenotype.