Rubinstein-Taybi syndrome (RSTS) is a rare genetic disorder. It is estimated that it affects about 1 case per 100,000 newborns. Weight and length are normal at birth, but growth is slow in infancy and childhood, with the mean final height significantly less than average.

Symptoms and findings typically found in individuals with RSTS may include:

Facial features such as a low frontal hairline, arched thick eyebrows, downslanting palpebral fissures, a prominent beaked nose with columella below the alae nasi, low-set/malformed ears, an arched palate, mild micrognathia, dental anomalies, and an atypical smile with nearly completely closed eyes.

Digital abnormalities such as broad thumbs and broad great toes, and clinodactyly of fifth finger, meaning that the little finger (pinky) curves to one side,

Skeletal abnormalities such as vertebral anomalies, ligamentous laxity, and severe, prolonged aseptic inflammation of the femoral head.

Complex neuro-radiological issues may include dysgenesis of the corpus callosum, Chiari type 1 malformation, Dandy-Walker malformation, and hydrocephalus and tethered cord.

A third of people may have cardiovascular problems. These are usually simple problems like isolated septal defects or patent ductus arteriosus, but more complicated problems like tricuspid atresia and pulmonary atresia have also been reported.

Urogenital issues may include renal anomalies and cryptorchidism.

Skin issues may include excessive hair growth (hirsutism), port-wine stain (naevus flammeus) on the forehead, and unusual scarring (keloid formation).

Ocular anomalies may occur in the majority (84%) of patients and include glaucoma, strabismus, cataract, refractive errors, defects in the iris, lens, or retina (colobomata), and anterior segment dysgenesis.

Developmental delay and learning difficulty are common but the degree may vary from patient to patient.

Recurrent respiratory tract infections may occur in up to 75% of individuals with RSTS and are thought to be caused by an associated immune deficiency.

The behavioural phenotype of children with RSTS is described as friendly and having good social contacts. However, short attention spans and hyperactivity can be present, and during adolescence, anxiety, mood instability, and aggressive behaviour can emerge.

Two genes are currently known to be associated with RSTS, CREBBP and EP300. Pathogenic variants of the CREBBP gene account for about 50–60% of cases and pathogenic variants of EP300 account for another 5–8% of cases. In the remaining cases, the responsible gene is not identified. Other genes may be found to be associated with RSTS in the future.

What is Genetic Testing?

Genetic testing – sometimes called genomic testing, finds changes in the genetic material that can cause health problems. It is mainly used to diagnose rare and inherited health conditions and some cancers.

You may be offered a genetic test because your doctor thinks

• you or your child might have a health condition caused by a change in the genetic material involving one or more genes or certain chromosomes.
• someone in your family has a health condition that is caused by changes in the genetic material involving one or more genes, or certain chromosomes.
• some of your close relatives have had a particular type of cancer that could be inherited.

At Schell Genetics, we are here to assist you in this process. Please don’t hesitate to contact us.