Jul 01, 2016
Additional sex combs-like 2
The ASXL2 gene is the human homolog of the Drosophila asx gene. The asx gene enhances the function of a gene that codes for a protein involved in transcriptional activation and silencing (Katoh and Katoh, 2003).
The participant, an 8-year-old male who is larger than average (macrosomia) and has atypical facial features (including a large birthmark on his forehead (glabellar hemangioma)), a decrease in brain white matter (cerebral white matter atrophy), learning difficulties, and mild developmental delays was found to carry the following de novo genetic variant in the ASXL2 gene: c.2424delC/p.P808fs.
Since infancy, the patient’s height, weight and head circumference have been above the 95th percentile, and X-rays have shown advanced bone age. He had two heart problems (ventricular septal defect, patent ductus arteriosus) that resolved on their own. At age 5, he was diagnosed with weak cartilage in the walls of his trachea and bronchial tubes (tracheomalacia and bronchomalacia). Currently he has a slightly prolonged QT interval, sleep apnea, and elevated liver enzymes (transaminases).
The patient also has atypical facial features, including a large birthmark on his forehead (glabellar hemangioma), widely spaced eyes (hypertelorism), a flat nasal bridge, slightly downslanting eyes (palpebral fissures), and small ears. He also has multiple small birthmarks (capillary hemangiomas) on his chest, upper arms, and neck.
Developmentally, the patient has shown learning difficulties and aggressive behavior.
Some of his other features include:
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