Rubinstein Taybi Syndrome

The word “syndrome” is a medical term for a group of phenomena, such as physical characteristics, developmental course and medical aspects which are all traced to a common cause. The name Rubinstein – Taybi syndrome comes from the doctors who first described the features well: in 1963, described the American pediatrician and radiologist Hoos Hang Jack Rubinstein Taybi (both deceased in 2006) 7 children with the syndrome.They called it the self-inch wide / wide toe syndrome. Only later was the name of both researchers associated with this syndrome. It has been found not really the first ones who described a number of Greek orthopedic surgeons did so in 1957. Since then, however, called Rubinstein-Taybi syndrome (RTS) has been established, its name has not changed.

Disease characteristics. Rubinstein-Taybi syndrome (RSTS) is characterized by distinctive facial features, broad and often angulated thumbs and great toes, short stature, and moderate to severe intellectual disability. The characteristic craniofacial features are downslanting palpebral fissures, columella extending below the nares, highly arched palate, grimacing smile, and talon cusps. Prenatal growth is often normal; however, height, weight, and head circumference percentiles rapidly drop in the first few months of life. Obesity may occur in childhood or adolescence. IQ scores range from 25 to 79; average IQ is between 36 and 51. Other variable findings are coloboma, cataract, congenital heart defects, renal abnormalities, and cryptorchidism.

Diagnosis/testing. The diagnosis of RSTS is primarily based on clinical features. Chromosome abnormalities are occasionally observed on routine cytogenetic testing. CREBBP and EP300 are the only genes currently known to be associated with RSTS. FISHanalysis of CREBBP, available on a clinical basis, detects microdeletions in approximately 10% of individuals with RSTS. Sequence analysis, also clinically available, detects CREBBP mutations in another 30%-50% of affected individuals. Mutations in EP300 are identified in approximately 3% of individuals with RSTS; such testing is available on a clinical basis.

Management. Treatment of manifestations: Early intervention programs, special education, vocational training to address developmental disabilities, and referral to behavioral specialists/psychologists and support groups/resources for family members; standard treatment for eye abnormalities, hearing loss, cardiac defects, cryptorchidism, and sleep apnea; surgical repair of significantly angulated thumbs or duplicated halluces; aggressive management of gastroesophageal reflux and constipation.

Surveillance: Monitoring of growth and feeding, especially in the first year of life; annual eye and hearing evaluations; and routine monitoring for cardiac, dental, and renal anomalies.

Genetic counseling. RSTS is inherited in an autosomal dominant manner. RSTS typically occurs as the result of a de novomutation 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, the empiric recurrence risk for sibs is approximately 0.1%. Individuals with RSTS rarely reproduce. The theoretical risk to offspring is 50%. Prenatal testing for pregnancies at increased risk is possible if the disease-causing CREBBP or EP300 mutation or deletion in the family is known.

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