Rubinstein-Taybi syndrome (RSTS) is a rare autosomal dominant disorder characterized by distinct facial features, short stature, broad (often angulated) thumbs and great toes, and moderate to severe mental retardation. Facial features include arched eyebrows, down-slanting palpebral fissures, a beaked nose with long columella, high arched palate, and grimacing smile. Most patients develop obesity in childhood or adolescence. Other features may include eye findings, undescended testes, urinary tract anomalies, and congenital heart defects. Patients with RSTS also have an increased risk for tumors including meningioma, pilomatrixoma, rhabdomyosarcoma, pheochromocytoma, and leukemia. Pathogenic variants in the CREBBP gene have been identified in the majority of patients with RSTS. Approximately 10-20% of patients with RSTS have deletions involving the CREBBP gene. Pathogenic variants in the EP300 gene have also been identified in about 3-8% of patients with RSTS. This panel includes sequence and deletion/duplication analysis of both genes.
