Beals syndrome

Definition

Beals syndrome, also known as Beals contractural arachnodactyly (BCA), congenital contractural arachnodactyly, or Beals-Hecht syndrome, is a rare genetic disorder that involves the connective tissue of the skeleton.

Description

Individuals diagnosed with Beals syndrome usually have long, thin, fingers and toes that cannot be straightened out because of contractures, meaning a limited range of motion in the joints of their fingers, hips, elbows, knees, and ankles. They also have unusual external ears that appear crumpled. Contractures of the elbows, knees, and hips at birth are very common. Some babies also have clubfoot , causing one or both feet to be turned in towards each other at the ankles. In most individuals, the contractures improve with time and the clubfoot responds well to physiotherapy.

The condition occurs when fibrillin, an important component of the body's connective tissue (the glue and scaffolding of the body; for example bones, cartilages, tendons, and fibers) is not made properly by the body. The gene responsible for making fibrillin is called FBN2 and it is located on chromosome 5. Any mutation (change) occurring in the FBN2 gene results in Beals syndrome.

Genetic profile

Beals syndrome is caused by a mutation occurring in a gene. Genes are units of hereditary material passed from a parent to a child through the egg and sperm. The information contained in genes is responsible for the development of all the cells and tissues of the body. Most genes occur in pairs: one copy of each pair is inherited from the egg cell produced by the mother and the other copy of each pair comes from the sperm cell of the father. One of these genes (called FBN2) tells the body how to make fibrillin-2, a specific type of protein. Proteins are substances made in the body that consist of chemicals called amino acids. Fibrillin-2 is an important part of connective tissue. Connective tissue provides structural support and elasticity to the body. It is made up of various components, including elastic-like fibers, and fibrillin-2 is thought to play a role in ensuring that the elastic fibers of the connective tissue are assembled properly early in development; however, the precise function of fibrillin-2 remains unknown. People with Beals syndrome have a mutation in one copy of their FBN2 gene. As a result, the fibrillin-2 they make is unable to work properly and this causes the BCA symptoms.

Beals syndrome is inherited as a dominant condition. In dominant conditions, a person needs to have only one altered gene copy to develop the condition. The mutation in the FBN2 gene that causes Beals syndrome can be inherited from a parent who is also affected with BCA. Individuals with Beals syndrome have a 50% chance in each pregnancy to have a child with Beals syndrome.

Sometimes Beals syndrome cannot be traced back to a parent with the condition. In these cases, the genetic change is said to be a spontaneous mutation. This means that some unknown event has caused the FBN2 gene (which functions normally in the parent) to mutate in either the sperm of the father or the egg of the mother. If fertilization occurs, the resulting individual will have Beals syndrome. A person who has Beals syndrome due to a spontaneous mutation can then pass on this altered FBN2 gene to his or her future children.

Demographics

Beals syndrome affects males and females of all ethnic groups. It is a rare condition and accurate estimates of the number of affected people are not available.

Signs and symptoms

Besides the general appearance displayed by persons with Beals syndrome (tall and thin, contractures, with typical crumpled ear), symptoms of the disorder vary from one affected individual to the next. Sometimes, arms are disproportionately long for the height of the person. Other less common features may include a small chin, protruding forehead, and a high arch in the roof of the mouth (palate).

An abnormal bending or twisting of the spine (kyphosis/scoliosis) is seen in about half of individuals diagnosed with Beals syndrome and can occur in early infancy. This bending and twisting of the spine tends to worsen over time. Some individuals may also have an abnormal indentation or protrusion of their chest wall. Decreased muscle bulk, especially in the lower legs, is also a common sign of Beals syndrome.

Less common symptoms of Beals syndrome include heart and eye problems. The most frequent heart problem involves one of the heart valves (mitral valve prolapse) and may necessitate medication prior to dental or other surgeries so as to prevent infection. More serious heart problems may occur but are rare. The aorta, the major blood vessel carrying blood away from the heart, may occasionally enlarge. This condition usually requires medication to prevent further enlargement or rarely, surgery. A small number of individuals with Beals syndrome may also be nearsighted and require eye glasses.

Diagnosis

The diagnosis of Beals syndrome is based on the presence of specific conditions. The diagnosis is suspected in anyone with the typical features of Beals syndrome such as tall, slender stature, contractures of many joints including the elbows, knees, hips, and fingers, abnormal curvature of the spine, decreased muscle bulk, and crumpled ears. As of 2001, a genetic test to confirm a BCA diagnosis has yet to become routinely available. Genetic testing for this syndrome remains limited to a few research laboratories around the world.

Testing during pregnancy (prenatal diagnosis) to determine whether the unborn child of at-risk parents may be affected by BCA is not routinely available. Also, because of the rather mild nature of the condition in most individuals, prenatal diagnosis is usually not requested. There has been at least one documented prenatal diagnosis for Beals syndrome. Using a procedure called amniocentesis , fluid surrounding the developing baby was removed and cells from that fluid were submitted to genetic testing in a research laboratory. The procedure allowed confirmation that the unborn child was affected with Beals syndrome.

Treatment and management

There is no cure for Beals syndrome. Management of the disorder usually involves physiotherapy in early childhood to increase joint mobility and to lessen the effects of low muscle bulk. The contractures have been known to spontaneously improve, with surgery sometimes required to release them.

The abnormal curvature of the spine tends to worsen with time. A bone specialist should be consulted for advice on the appropriate treatment. Some individuals may require a back brace and/or surgery to correct the curvature.

A heart specialist should be consulted because some individuals with Beals syndrome have been known to have heart defects. Usually, an ultrasound of the heart is taken to assess whether there are any abnormalities. Medications may be used to treat some types of heart problems, if any. An eye specialist should also be consulted because of the possibility of eye problems such as myopia (nearsightedness). Prescription eye glasses may be necessary.

Individuals with Beals syndrome and their families may benefit from genetic counseling for information on the condition and recurrence risks for future pregnancies.

Prognosis

There tends to be gradual improvement in the joint contractures with time. The abnormal spinal curvature tends to get worse over time and may require bracing or surgery. The life span of individuals with Beals syndrome is not altered.

Resources

PERIODICALS

Robinson, Peter N., M. Godfrey. "The molecular genetics of Marfan syndrome and related microfibrillinopathies." Journal of Medical Genetics 37(2000): 9-25.

ORGANIZATIONS

AVENUES National Support Group for Arthrogryposis Multiplex Congenita. PO Box 5192, Sonora, CA 95370. (209) 928-3688. [email protected]. <http://www.sonnet.com/avenues>.

National Marfan Foundation. 382 Main St., Port Washington, NY 11050-3121. (800) 862-7326. <http://www.marfan.org>.

National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. <http://www.rarediseases.org>.

OTHER WEBSITES

Godfrey, Maurice. "Congenital Contractural Arachnodactyly." GeneClinics. Univeristy of Washington, Seattle. <http://www.geneclinics.org>. (March 6, 2001)

Nada Quercia, Msc, CCGC CGC