Background: Blepharophimosis is a fixed reduction in the vertical distance between the upper and lower eyelids with short palpebral fissures. It is a rare facial malformation and is considered an important diagnostic feature in dysmorphic analysis. It is likely that many patients with blepharophimosis-mental retardation syndrome have submicroscopic chromosomal rearrangements, and the use of molecular karyotyping can narrow the known blepharophimosis-mental retardation-critical regions or clarify the effect of the haploinsufficiency of the involved genes on the phenotype.
Materials and methods: A female patient presented with bilateral blepharophimosis, ptosis, epicanthus inversus, telecanthus, low-set and small ears, other minor anomalies, hypotonia and psychomotor developmental delay. Metabolic investigations and array CGH analysis were performed. The results of molecular karyotyping were confirmed by real-time PCR analysis.
Results: Molecular karyotyping revealed a 5.2 Mb deletion in the 10q22.1q22.3 region. Real-time PCR analysis of the proband and her parents confirmed the deletion in the proband and revealed its de novo origin.
Conclusions: With ptosis, hypotonia, and developmental delay as the main diagnostic features of our patient, the effect of histone acetyltransferase-encoding KAT6B gene haploinsufficiency was suspected to have a significant role in determining the phenotype. Detailed clinical characterization of the patient provided additional information on the clinical manifestation of the 10q22 deletion.
Keywords: 10q22 deletion; KAT6B gene; blepharophimosis; intellectual disability; ptosis.