Apert syndrome
Apert syndrome | |
---|---|
Other names | Acrocephalo-syndactyly type 1 FGFR2 gene (two-thirds of cases) |
Apert syndrome is a form of
In 1906,
In embryology, the hands and feet have selective cells that die in a process called selective cell death, or apoptosis, causing separation of the digits. In the case of acrocephalosyndactyly, selective cell death does not occur and skin, and rarely bone, between the fingers and toes fuses.
The cranial bones are affected as well, similar to
Findings for the incidence of the syndrome in the population have varied,[3] with estimates as low as 1 birth in 200,000 provided[4] and 160,000 given as an average by older studies.[5][6] A study conducted in 1997, however, by the California Birth Defects Monitoring Program found an incidence rate of 1 in 80,645 out of almost 2.5 million live births.[7] Another study conducted in 2002 by the Craniofacial Center, North Texas Hospital for Children, found a higher incidence of about 1 in 65,000 live births.[3]
Signs and symptoms
Craniosynostosis
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Casazza_4.jpg/220px-Casazza_4.jpg)
The cranial malformations are the most apparent effects of acrocephalosyndactyly.
Syndactyly
All acrocephalosyndactyly syndromes show some level of limb anomalies, so it can be hard to tell them apart. However, the typical hand deformities in patients with Apert syndrome distinguish it from the other syndromes.[11] The hands in patients with Apert syndrome always show four common features:[12]
- a short thumb with radial deviation
- complex syndactyly of the index, long and ring finger
- symbrachyphalangism
- simple syndactyly of the fourth webspace
The deformity of the space between the index finger and the thumb may be variable. Based on this first webspace, three different types of hand deformation can be diffentiated:
- Type I: Also called a "spade hand". The most common and least severe type of deformation. The thumb shows radial deviation and clinodactyly but is separated from the index finger. The index, long and ring finger are fused together in the distal interphalangeal joints and form a flat palm. During the embryonic stage, the fusion has no effect on the longitudinal growth of these fingers, so they have a normal length. In the fourth webspace, we always see a simple syndactyly, either complete or incomplete.
- Type II: Also called a "spoon" or "mitten" hand. This is a more serious anomaly since the thumb is fused to the index finger by simple complete or incomplete syndactyly. Only the distal phalanx of the thumb is not joined in the osseous union with the index finger and has a separate nail. Because the fusion of the digits is at the level of the distal interphalangeal joints, a concave palm is formed. Most of the time, we see complete syndactyly of the fourth webspace.
- Type III: Also called the "hoof" or "rosebud" hand. This is the most uncommon but also most severe form of hand deformity in Apert syndrome. There is a solid osseous or cartilaginous fusion of all digits with one long, conjoined nail. The thumb is turned inwards and it is often impossible to tell the fingers apart. Usually proper imaging of the hand is very difficult, due to overlap of bones, but physical examination alone is not enough to measure the severity of deformation.
Type I ("spade") | Type II ("mitten") | Type III ("rosebud") | |
---|---|---|---|
First webspace | Simple syndactyly | Simple syndactyly | Complex syndactyly |
Middle three fingers | Side-to-side fusion with flat palm | Fusion of fingertops forming a concave palm | Tight fusion of all digits with one conjoined nail |
Fourth webspace | Simple and incomplete syndactyly | Simple and complete syndactyly | Simple and complete syndactyly |
Dental significance
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Patient_with_Apert_syndrome.jpg/220px-Patient_with_Apert_syndrome.jpg)
Common relevant features of acrocephalosyndactyly are a high-arched palate, pseudomandibular prognathism (appearing as mandibular prognathism), a narrow palate and crowding of the teeth.
Other signs
Omphalocele has been described in two patients with Apert syndrome by Herman T.E. et al. (USA, 2010) and by Ercoli G. et al. (Argentina, 2014). An omphalocele is a birth defect in which an intestine or other abdominal organs are outside of the body of an infant because of a hole in the bellybutton area. However, the association between omphalocele and Apert syndrome is not confirmed yet, so additional studies are necessary.[13][14]
Causes
Acrocephalosyndactyly may be an
Apert syndrome is an autosomal dominant disorder; approximately two-thirds of the cases are due to a C to G mutation at the position 755 in the
It is still not very clear why people with Apert syndrome have both craniosynostosis and syndactyly. There has been one study that suggests it has something to do with the expression of three
Diagnosis
Diagnosis is typically by the apparent physical characteristics and can be aided by skull X-ray or head CT examination. Molecular genetic testing can confirm the diagnosis.[21]
Treatments
Craniosynostosis
Surgery is needed to prevent the closing of the coronal sutures from damaging brain development. In particular, surgeries for the LeFort III or monobloc midface distraction osteogenesis which detaches the midface or the entire upper face, respectively, from the rest of the skull, are performed in order to reposition them in the correct plane. These surgeries are performed by both plastic and oral and maxillofacial (OMS) surgeons, often in collaboration.[citation needed]
Syndactyly
There is no standard treatment for the hand malformations in Apert due to the differences and severity in clinical manifestations in different patients. Every patient should therefore be individually approached and treated, aiming at an adequate balance between hand functionality and aesthetics. However, some guidelines can be given depending on the severity of the deformities. In general it is initially recommended to release the first and fourth interdigital spaces, thus releasing the border rays.[22] This makes it possible for the child to grasp things by hand, a very important function for the child's development. Later the second and third interdigital spaces have to be released. Because there are three handtypes in Apert, all with their own deformities, they all need a different approach regarding their treatment:[23]
- Type I hand usually needs only the interdigital web space release. First web release is rarely needed but often its deepening is necessary. Thumb clinodactyly correction will be needed.
- In type II hands it is recommended to release the first and fifth rays in the beginning, then the second and the third interdigital web spaces have to be freed. The clinodactyly of the thumb has to be corrected as well. The lengthening of the thumb phalanx may be needed, thus increasing the first web space. In both type I and type II, the recurrent syndactyly of the second web space will occur because of a pseudoepiphysis at the base of the index metacarpal. This should be corrected by later revisions.
- Type III hands are the most challenging to treat because of their complexity. First of all, it is advised to release the first and fourth webspace, thus converting it to type I hand. The treatment of macerations and nail-bed infections should also be done in the beginning. For increasing of the first web space, lengthening of the thumb can be done. It is suggested that in severe cases an amputation of the index finger should be considered. However, before making this decision, it is important to weigh the potential improvement to be achieved against the possible psychological problems of the child later due to the aesthetics of the hand. Later, the second and/or third interdigital web space should be released.
With growing of a child and respectively the hands, secondary revisions are needed to treat the contractures and to improve the aesthetics.
See also
- Other craniosynostosis syndromes:
- Hearing loss with craniofacial syndromes
References
- ^ "Apert syndrome – About the Disease". Genetic and Rare Diseases Information Center. Archived from the original on 18 May 2019. Retrieved 25 April 2023.
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- ^ "Apert Syndrome". NORD (National Organization for Rare Disorders). Retrieved 21 September 2022.
- ^ "Apert syndrome". GOSH Hospital site. Retrieved 21 September 2022.
- ^ "Apert Syndrome | Boston Children's Hospital". childrenshospital.org. Retrieved 21 September 2022.
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- ^ "Apert syndrome | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Retrieved 17 March 2018.
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