Rubinstein-Taybi syndrome

Rubinstein-Taybi syndrome (RTS) is a very rare genetic multi-system disorder primarily characterised by mental retardation, broad and often angulated thumbs and halluces, and distinctive facial features.

Epidemiology

The estimated incidence is 1 in 100,000-125,000 live births ⁵.

Clinical presentation

The presence of a syndrome is usually evident at birth and becomes more obvious with increasing age as developmental delay becomes more pronounced. Features include ⁵:

• facial appearance
  • high arched eyebrows
  • long eyelashes
  • down-slanting palpebral fissures
  • broad nasal bridge/beaked nose
  • high arched palate
  • mild micrognathia
  • unusual facial expression: the grimacing or at least unusual smile with an almost closing of the eyes
  • talon cusps of the permanent incisors
• limbs
  • broad thumbs and broad big toes (almost always present)
  • partial duplication of the first ray (hands or feet)
  • radially deviated thumbs and halluces
  • broadening of the terminal phalanges of the fingers
  • persistent fetal pads,
  • clinodactyly of the fifth fingers 
• skull and central nervous system
  • microcephaly
  • mental retardation (IQ 35-50)
• congenital cardiac abnormalities: reported in up to 33% of affected patients ²
  • patent ductus arteriosus
  • atrial septal defects
  • ventricular septal defect
• hirsutism

Pathology

Most cases are thought to be sporadic deriving from de novo mutations at a locus on band 16p13.3, which encompasses the gene for the transcription co-factor cyclic adenosine monophosphate response element–binding protein–binding protein.

Other cases are due to a mutation in either CREB-binding protein (CBP(CBP) or E1A-binding protein (p300) ⁵.

Radiographic features

The radiology reflects the morphological abnormalities described above, particularly of the face, skull and limbs. 

Treatment and prognosis

Despite an increased risk of developing intracranial tumours (meningioma and other brain tumours), and leukaemia (which tend to occur before 15 years of age) life expectancy appears to be normal ⁵. 

While significant advances in the knowledge of clinical manifestations and natural history of RTS have been made, guidelines for the healthcare and follow-up care of RTS have not been well updated after the proposal of Wiley et al. in 2003 ⁶.