Rubinstein-Taybi syndrome is an autosomal dominant syndrome characterized by mental retardation, broad thumbs and toes, and facial abnormalities.

Synopsis

 systemic anomalies

• postnatal growth retardation

 carniofacila anomalies

• microcephaly
• large anterior fontanelle
• late closure of fontanelle
• frontal bossing
• low anterior hairline
• hypoplastic maxilla
• micrognathia
• low set ears
• heavy eyebrows
• long eyelashes
• ptosis
• epicanthal folds
• strabismus
• nasolacrimal duct obstruction
• cataracts
• glaucoma
• coloboma
• downward slanting palpebral fissures
• beaked nose
• deviated nasal septum
• small opening of the mouth
• narrow palate
• dental crowding

 talon cusps
 patent ductus arteriosus
 atrial septal defects
 ventricular septal defects
 capillary hemangiomas
 sternal anomalies
 hypospadias
 cryptorchidism
 shawl scrotum

 skeletal anomalies

• delayed skeletal maturation
• large foramen magnum
• parietal foramina
• scoliosis Spina bifida occulta
• small, flared iliac wings
• patellar dislocation
• broad thumbs with radial angulation
• fifth finger clinodactyly
• persistent fetal fingertip pads
• syndactyly
• polydactyly
• broad great toes
• plantar crease between first and second toes
• pes planus
• single transverse palmar creases

 cutaneous anomalies

• keloid formation in surgical scars
• capillary hemangiomas
• cafe-au-lait spots
• multiple pilomatricomas (pilomatricomatosis)

 hirsutism
 agenesis of corpus callosum

 predisposition to tumors (head and neck ++)

• keloid formation in surgical scars
• capillary hemangiomas
• cafe-au-lait spots
• multiple pilomatricomas (pilomatricomatosis)

Cytogenetics

 16p13.3 chromosomal anomalies

• 10% of submicroscopic deletions of 16p13.3 detectable by FISH
• 16p13.3 translocations
• 16p13.3 inversions

Etiology

 mutation in the gene CREBBP encoding the transcriptional coactivator CREB-binding protein (MIM.600140) at 16p13.3

• truncating mutations in CREBBP in 10% of patients

 mutation in the gene EP300 (MIM.602700) at 22q13 encoding 300-kD E1A-binding protein (EP300)