Rubinstein
Taybi SyndromeThis syndrome only with a frequency of 1 in 300,000 births,
but is fairly commonly seen (1 in 600) in mental retardation clinics. The typical
features are broad malformed thumbs and big toes as well as typical facial abnormalities
and mental retardation. It is due to a spontaneous deletion of part of chromosome
16(16p13-)leading to these multiple abnormal fetal developments. Signs
and symptoms
Facial
deformities include an underdeveloped small maxilla with a narrow palate. Ears
are typically low set and often malformed. Sometimes there is a typical talon
cusp malformation in one or more incisor teeth as depicted in this image. This
person
shown in the link had only minimal features of Rubinstein Taybi syndrome,
but the typical dental abnormality triggered a chromosomal work-up and confirmed
the presence of this syndrome in this case. There are deformities
of thumb and big toe with a wide base and angulations towards the fingers
or toes. Syndactyly and polydactyly also exists in some cases. Several eye deformities
are also common like congenital glaucoma, retinal abnormalities and strabismus.
The child has growth retardation and as adults they do not grow taller
than 58 to 60 inches. The child has speech difficulties and a muscle weakness
problem (hypotonia). There are feeding problems. In girls hirsutism is common,
in boys cryptorchidism. Mental retardation is severe with an intelligence quotient
between 30 and 80, with 50% or more having an IQ of 50. Joint hypermobility poses
problems with patellofemoral instability and frequent patellar dislocations. Cardiac
malformations are common with ventricular septal defects, atrial septal defects,
patent ductus arteriosus etc. There is a high sensitivity to succinylcholine,
which is used generally with intubation general anesthesia during surgeries and
this can cause life threatening cardiac arrhythmias. Prognosis
The prognosis depends on the mix of congenital conditions present. Attention
to detail by the cardiologist, neurologist, pediatrician, orthopedic surgeon and
ophthalmologist will give the baby the best chance of survival. However, the limiting
conditions are any cardiac malformation, feeding problems with possible aspiration
pneumonia and subsequent infection and possible blindness, if the congenital eye
abnormality is serious.
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