Rubinstein Taybi Syndrome
Other names of Rubinstein Taybi Syndrome
Rubinstein Taybi (RTS) broad thumb-hallux syndrome
Causes of Rubinstein Taybi Syndrome
RSTS occurs as the result of a new (de novo) gene mutation, although rarely, the syndrome has been inherited from an affected parent in an autosomal dominant pattern.
Symptoms of Rubinstein Taybi Syndrome
Affected infants may have abnormalities of the eyes including eyes that appear widely spaced (apparent hypertelorism),crossed eyes (strabismus), upper eyelids that droop (ptosis), and extra folds of skin on either side of the nose that may cover the eye’s inner corners (epicanthal folds).
There may be additional skeletal abnormalities including abnormal side-to-side (scoliosis) or front-to-back (kyphosis) curvature of the spine, abnormal depression of the bone forming the center of the chest (sternum), known as
funnel chest or pectus excavatum, abnormalities of vertebrae and the pelvis, malformations of ribs, and recurrent dislocation of the knee caps. The lower end of the spinal cord may be abnormally tied down (tethering).
Male infants with RSTS may have abnormalities of the genitourinary tract including failure of one or both testes to descend into the scrotum (cryptorchidism), an abnormal fold of skin extending around the base of the penis (shawl scrotum), and/or misplacement of the urinary opening, such as on the underside of the penis (hypospadias).
In addition, infants with RSTS may have underdeveloped (hypoplastic) or absent kidney(s), repeated infections of the urinary tract, kidney stones, unusual accumulation of urine in the kidney (hydronephrosis), and/or backflow (reflux) of urine into the tubes (ureters) that normally bring urine to the bladder.
In some cases, duplication of the kidneys and/or ureters may also be present
Approximately one third of infants with RSTS have an associated heart defect that is present at birth (congenital heart defect).
According to the medical literature, patent ductus arteriosus may be the most common congenital heart defect present in infants with RSTS.
Infants with RSTS may also have extra heart sounds (heart murmurs), abnormal narrowing of the opening between the pulmonary artery and the right ventricle of the heart (pulmonary stenosis), narrowing of the aorta (aortic coarctation), and ventricular septal defects (VSDs) and/or atrial septal defects (ASDs).
The symptoms associated with a ventricular septal defect or atrial septal defect vary from person to person, depending upon the size and location of the defect.
Affected individuals may also have abnormalities of the respiratory system. The lungs may be abnormally divided into small extra sections (lung lobulation) and/or the walls of the voice box (larynx) may be weak and easily collapsible, potentially resulting in swallowing and breathing difficulties (e.g., temporary cessation of normal breathing rhythm during sleep [sleep apnea]).
Individuals with RSTS often exhibit a short attention span, decreased tolerance for noise and crowds, impulsivity, and moodiness. Autistic behaviors are common.
Diagnosis of Rubinstein Taybi Syndrome
The diagnosis of RSTS is primarily based on physical (clinical) features, including a downward to the eyes (downslanted palpebral fissures), a low-hanging nasal septum (columella), a high palate, cusp-like structures (talon cusps) on the front teeth, and/or broad and angulated thumbs and great toes.
The diagnosis may be further supported through x-ray studies revealing malformations of the bones of the hands and feet characteristic to RSTS.
Genetic testing (FISH or sequence analysis) may confirm RSTS, including pathogenic variants in the CREBBP gene (identified in 50%-60% of affected individuals) or in the EP300 gene (identified in 3%-8% of RSTS individuals).
Treatment of Rubinstein Taybi Syndrome
The management of RSTS is directed toward the specific symptoms of each individual.
Management may require the coordinated efforts of a team of specialists, including pediatricians, physicians who diagnose and treat heart abnormalities (cardiologists), skeletal abnormalities (orthopedists), hearing problems (audiologists), urinary tract abnormalities (urologists), kidney dysfunction(nephrologists), as well as dental specialists, physical therapists, speech pathologists, dietitians, and/or other health care professionals.
Growth parameters should be regularly plotted on an RSTS-specific growth chart.
There should be yearly eye and hearing evaluations and routine monitoring for cardiac, dental, and renal abnormalities.
Orthopedic surgery, physical therapy, and/or other supportive techniques may help treat certain skeletal abnormalities potentially associated with RSTS, such as scoliosis.
In some cases, surgery may be performed on the hands and/or feet, particularly when there are extra (supernumerary) fingers and/or toes, or when the fingers are severely misaligned.
Affected individuals may require early intervention to prevent and/or monitor respiratory and feeding difficulties. Special education programs, vocational training, speech, and/or behavioral therapy may also be recommended.
Genetic counseling is recommended for affected individuals and their family members.