Apert syndrome

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at March 9, 2016
StartDiseasesApert syndrome

Apert syndrome, which is alternatively known as type 1 acrocephalosyndactyly, is a genetic disorder that manifests itself in the premature fusion of certain skull bones. There are several other related types of acrocephalosyndactyly: type 2 is called Crouzon syndrome, type 3 is called Saethre-Chotzen syndrome, and type 5 is called Pfeiffer syndrome. Individuals with Apert syndrome have malfunctions in their hands, feet, skulls and faces.

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Definition & Facts

Apert syndrome causes premature fusion of skull bones, which creates a condition called craniosynostosis in which the brain continues to grow inside of the restricted skull, putting pressure on the face and skull.

The condition was discovered and was named after French scientist Eugene Apert in the early 20th century, and its name references two readily identifiable characteristics of the condition: the peaked head that patients exhibit (in Greek, "acro" and "cephalo"), and the webbed fingers and toes that the condition causes.

The congenital disease is relatively rare, but doctors generally disagree over exactly how widespread it is in the population: different estimates state that 1 in every 65,000, 1 in every 88,000, or 1 in every 200,000 babies are diagnosed with Apert syndrome.

Symptoms & Complaints

Most symptoms of Apert syndrome are immediately apparent to the naked eye. Babies with Apert syndrome experience unnatural head and facial growth: their heads are usually extremely long, their foreheads are high and pronounced, their eyes are wide-set and tend to bulge, their eyelids have difficulty closing, and the middle of their faces is sunken and peaked inward. The lower jaw is also noticeably underdeveloped, which leads to severe dental problems such as crowded teeth and difficulty closing the mouth fully.

Other symptoms present themselves as the result of further testing. Many babies and toddlers with Apert syndrome have extremely poor vision because of their irregularly shaped eye sockets; others have diminished cognitive abilities, although this particular symptom does not impact all babies with the condition.

Other symptoms include an increased propensity for obstructive sleep apnea, repeated incidences of ear infections or sinus infections, and moderate to severe hearing loss. Abnormal fusion of the bones in hands and feet is another symptom that is readily observable: infants with Apert syndrome have webbed hands and feet, and although the number of digits affected varies from case to case, a minimum of three fingers or toes on each hand are connected to one another. Other common symptoms include various heart, gastrointestinal and urinary problems.

Causes

Apert syndrome is an autosomal dominant disorder, which means that only one random mutation on a gene is necessary to cause the disorder. The mutation is generally considered to be random, and it does not have to be present or active in both parents to manifest in a newborn.

The gene that must mutate to cause Apert syndrome is referred to as FGFR2. Among the responsibilities of this gene is the production of fibroblast growth factor receptor 2. When the mutation occurs, the protein that instructs immature cells on when to become bone cells is disrupted, causing the premature fusion of bone structures during embryonic growth. The main result of the mutation is an increased activity period for the protein, meaning that it causes cells to become bone at too quick of a pace. The fusion occurs mainly in the head, hands and feet.

Most individuals with Apert syndrome have no history of the disease in their family, but those afflicted can pass it on more easily to their offspring. Males and females appear to be affected equally, in cases that are equally random.

Diagnosis & Tests

Typically, Apert syndrome is diagnosed on sight by either the delivery doctor at the hospital or during a subsequent visit. Physical examinations, such as hand, foot, and skull X-rays, are often performed, and hearing tests are generally administered. If the doctor is unsure, they may order specific genetic testing that can check if genetic mutation is the cause of the skull formation, but generally the visual symptom combination is unmistakable.

Treatment & Therapy

There is no known cure for Apert syndrome; the bone deformities are typically treated by employing a wide range of surgical options. When the infant is anywhere from 6 to 8 months old, surgeons generally perform a procedure called craniosynostosis release. This surgery entails manual separation and rearrangement of bones in the skull.

Additional corrective surgeries must be performed throughout childhood and adolescence in order to realign the jaw and cheek bones. The final facial surgery is usually a hypertelorism correction, which corrects the patient's wide-set eyes by removing a small piece of bone between the eyes in the skull.

Other treatments seek to correct different aspects of the syndrome's effects. Frequent administration of eyedrops can help to counteract dry eyes, and antibiotic treatment can help protect the sensitive immune system against bacterial infections.

There are several different treatments for sleep apnea, including wearing a breathing mask during sleeping hours, using continuous positive airway pressure machines, and undergoing surgical tracheostomies. Myringotomy, or the placement of ear tubes, helps protect against frequent ear infections.

There is no scientific or medical consensus on a general approach to webbed toes and fingers, but individual surgical treatments strive to provide an adequate balance between functionality and aesthetics. There are three variations of "hand types" in Apert syndrome, and all must be approached differently from a surgical perspective.

Prevention & Prophylaxis

Because Apert syndrome is a randomly occurring condition that is caused by a singular mutation in one particular gene, it is difficult to take any steps to meaningfully prevent its occurrence. Prospective parents can undergo a series of genetic testing to check for genetic mutations. Children with Apert syndrome are still capable of living normal lives, and parents of a child with the syndrome should consult with doctors, surgeons, and genetic specialists to determine the best path forward.