Cryptic subtelomeric 6p deletion in a girl with congenital malformations and severe language impairment

Several cases with microscopically visible, terminal 6p deletions have been described, and a distinct clinical phenotype has emerged, including developmental delay, congenital heart malformations, ocular abnormalities, hearing loss and a characteristic facial appearance. We report a patient with a submicroscopic 6p deletion, detected by subtelomeric screening using fluorescence in situ hybridisation. This girl presented with typical facial dysmorphic features, hearing impairment, malformation of the anterior eye segment, an ASD and severe language impairment. However, her cognitive functions were within the normal range. Detailed FISH analysis with 20 BAC probes covering the distal 6p25 region estimated the size of the terminal deletion to 2.1 Mb, and thus this case narrows down the critical region for the 6p phenotype. The forkhead transcription factor gene FOXC1, involved in a spectrum of anterior eye chamber disorders, is deleted in this patient, together with several characterised and putative genes with yet unknown function.