Clinical characteristics: Rubinstein-Taybi syndrome (RSTS) is characterized by distinctive facial features, broad and often angulated thumbs and halluces, short stature, and moderate-to-severe intellectual disability. The characteristic craniofacial features are downslanted palpebral fissures, low-hanging columella, high palate, grimacing smile, and talon cusps. Prenatal growth is often normal, then height, weight, and head circumference percentiles rapidly drop in the first few months of life. Short stature is typical in adulthood. Obesity may develop in childhood or adolescence. Average IQ ranges between 35 and 50; however, developmental outcome varies considerably. Some individuals with EP300-RSTS have normal intellect. Additional features include ocular abnormalities, hearing loss, respiratory difficulties, congenital heart defects, renal abnormalities, cryptorchidism, feeding problems, recurrent infections, and severe constipation.
Diagnosis/testing: The diagnosis of RSTS is established in a proband with characteristic clinical features. Identification of a heterozygous pathogenic variant in CREBBP or EP300 confirms the diagnosis if clinical features are inconclusive.
Management: Treatment of manifestations: Early intervention programs, special education, vocational training to address developmental disabilities, referral to behavioral specialists / psychologists, and support groups / resources for family members; standard treatment for eye abnormalities, hearing loss, sleep apnea, cardiac anomalies, renal anomalies, cryptorchidism, and dental anomalies; aggressive management of gastroesophageal reflux and constipation; surgical repair of significantly angulated thumbs or duplicated halluces.
Surveillance: Monitoring of growth and feeding, especially in the first year of life; annual eye and hearing evaluations; routine monitoring for cardiac, renal, and dental anomalies.
Genetic counseling: RSTS is inherited in an autosomal dominant manner. RSTS typically occurs as the result of a de novo pathogenic variant in the family; most individuals represent simplex cases (i.e., the only affected member in a family). In most instances, the parents of an individual with RSTS are not affected. When the parents are clinically unaffected, sibs are still presumed to be at increased risk for RSTS because of the possibility of a mild phenotype in a heterozygous parent or parental somatic and/or germline mosaicism. The empiric recurrence risk for sibs is less than 1%. Individuals with RSTS rarely reproduce. The risk to offspring is 50%. Once the pathogenic variant has been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing are possible.
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