Ophthalmologic abnormalities in a de novo terminal 6q deletion

To correlate the clinical phenotype with the genotype of a boy with a terminal deletion of chromosome 6q and to compare these observations to previous reports of 6q deletions and review of the literature.

Careful clinical evaluation, conventional cytogenetic analysis on GTG-banded chromosomes and 244K array CGH analysis.

This 14 year old Saudi boy had modest mental retardation, seizures, microcephaly, cortical dysplasia, a non-comitant esotropia, impersistent eccentric gaze, congenital nystagmus, thick corneas, and substantial myopia. He had a de novo 10.79 Mb deletion on chromosome 6 from 6q25.3 to 6qter. The deleted region extended from nucleotide 159929512 to 170723629 and encompassed 87 genes. Eleven genes remained within the proband's deleted region after excluding genes located in deleted areas reported in phenotypically normal individuals. Among those 11 genes, only the TBP (TATA box binding protein) gene has been associated with any symptom or sign observed in our patient.

This boy had clinical features similar to patients reported with the 6q terminal deletion syndrome. In addition, he had an unusual ocular motility pattern and thick corneas, features that may be more common than previously recognized. Deleted genes in this area of chromosome 6 may contribute to ophthalmic abnormalities in addition to mental retardation.