Home Dentistry Articles Apert syndrome
Apert Syndrome, virtually synonymous with Acrocephalosyndactyly,
is a branchial arch syndrome, characterized by a number of clinical
features, resulting from a developmental anomaly. Specifically,
this syndrome affects the first branchial (or pharyngeal) arch,
which is the precursor of the maxilla and mandible. Since the
branchial arches are important developmental features in a growing
embryo, disturbances in its development create lasting and widespread
In 1906, Eugène Apert, a French physician,
first described nine people with a similar disorder. Since he
was the first to do so, his name is associated with the syndrome.
Breaking down the name of this disorder, "acro"
means "peak" in Greek and refers to the "peaked" hands of some
people with this syndrome. Syndactyly refers to the webbing
of fingers and toes.
What occurs in embryology is that hands and
feet are supposed to have some selective cells die (known as
selective cell death or apoptosis to separate the fingers and
toes. In the case of acrocephalosyndactyly, selective cell death
does not occur, and fusion of skin, and sometimes bone, between
the fingers and toes occur.
As in Crouzon Syndrome, the bones of the skull
are affected as well. Cranial synostosis results from the infant's
skull and facial bones fusing early while in development---
disabling the ability for normal bone growth. Fusion of different
sutures lead to different patterns of growth of the skull. Examples
include: trigonocephaly (fusion of the metopic suture), brachycephaly
(fusion of the metopic suture), dolichocephaly (fusion of the
sagittal suture), plagiocephaly (fusion of coronal and lambdoidal
sutures), oxycephaly (fusion of most sutures).
There is some support that acrocephalosyndactyly
occurs in an autosomal dominant mode, but the basic defect is
still unknown. Evidence for this is that males and females are
Nonetheless, almost all cases are sporadic,
signifying that most are attributable to fresh mutations or
an environmental insult to the genetic code. In 1995, A.O.M
Wilkie, along with other researchers, published a paper showing
evidence of a relationship between acrocephalosyndactyly and
a gene, called Fibroblast Growth Factor Receptor 2, on chromosome
There is also some evidence that the age of
the father is related to this syndrome. This stands in stark
contrast to Down Syndrome, where the age of the mother is positively
correlated with the risk of having a child with the syndrome.
It is speculated that older fathers are more likely to have
mutations in the chromosomes of their sperm, but a correlation
to this disorder has not been established through scientific
The cranial malformations are the most apparent
effects of acrocephalosyndactyly. Cranial synostosis occurs,
as explained above, with Brachiocephaly being the common pattern
of growth. Additionally, a common characteristic is a high,
prominent forehead and a flat posterior skull. Due to the premature
closing of sutures of the skull, increased cranial pressure
develops which sometimes leads to mental deficiency. Nonetheless,
this is not always the case since some of these people normal
intelligence. Furthermore, a flat or concave face may develop
because of a deficient growth in the mid-facial bones, leading
to a condition known as pseudomandibular prognathism. Other
features of acrocephalosyndactyly may be shallow bony orbits
and broadly spaced eyes.
Low-set ears is also a typical characteristic,
as is with all of these disorders that are called branchial
arch syndromes. The reason for this is that in fetal life all
ears are much lower than what we are accustomed to seeing. During
normal development, the ears "travel" upward on the
head but, in these cases, the ears do not follow this normal
pattern of development since these syndromes have the greatest
effects on the head.
The major attribute of this syndrome is syndactyly
of the hands and feet. Commonly there is fusion of fingers or
toes with usually an equal amount on both sides. It is usual
for the middle 3 fingers to be fused together. This appearance
is the characteristic for which acrocephalosyndactyly is named.
The thumb and big toe may be broad and malformed. This disorder
is progressive with age as the joints continue to appear present
but are immovable.
Surgery is needed to prevent the closing of
sutures in the skull from damaging brain development. Combined
orthodontic and orthognathic surgery can help to relieve some
of the facial deformities, such as the flat or concave face.
In particular, the LeFort III, a surgical procedure, can be
used to detach the midface from the rest of the skull to reposition
it appropriately. Additionally, aggressive surgery is needed
to separate as many fingers and toes as possible in life. As
of yet, there is no way to separate bones of the hands and fingers
once the fusion has taken place.
For dentists, this disorder is very important
to understand since most of the physical abnormalities are presented
in the head, and particularly the oral cavity. Common relevant
features of acrocephalosyndactyly are a high-arched palate,
pseudomandibular prognathism (appearing as mandibular prognathism),
a short width of the palate, and crowding of the teeth.