Kabuki syndrome
Kabuki syndrome
Definition
Kabuki syndrome is a rare disorder characterized by unusual facial features, skeletal abnormalities, and intellectual impairment. Abnormalities in different organ systems can also be present, but vary from individual to individual. There is no cure for Kabuki syndrome, and treatment centers on the specific abnormalities, as well as on strategies to improve the overall functioning and quality of life of the affected person.
Description
Kabuki syndrome is a rare disorder characterized by mental retardation, short stature, unusual facial features, abnormalities of the skeleton and unusual skin ridge patterns on the fingers, toes, palms of the hands and soles of the feet. Many other organ systems can be involved in the syndrome, displaying a wide variety of abnormalities. Thus, the manifestations of Kabuki syndrome can vary widely among different individuals.
Kabuki syndrome (also known as Niikawa-Kuroki syndrome) was first described in 1980 by Dr. N. Niikawa and Dr. Y. Kuroki of Japan. The disorder gets its name from the characteristic long eyelid fissures with eversion of the lower eyelids that is similar to the make-up of actors of Kabuki, a traditional Japanese theatrical form. Kabuki syndrome was originally known as Kabuki Make-up syndrome, but the term "make-up" is now often dropped as it is considered offensive to some families.
Scientific research conducted over the past two decades suggests that Kabuki syndrome may be associated with a change in the genetic material. However, it is still not known precisely what this genetic change may be and how this change in the genetic material alters growth and development in the womb to cause Kabuki syndrome.
Genetic profile
As stated above, the etiology of Kabuki syndrome is not completely understood. While Kabuki syndrome is thought to be a genetic syndrome, little or no genetic abnormality has been identified as of yet. Chromosome abnormalities of the X and Y chromosome or chromosome 4 have occurred in only a small number of individuals with Kabuki syndrome, but in most cases, chromosomes are normal.
In almost all cases of Kabuki syndrome, there is no family history of the disease. These cases are thought to represent new genetic changes that occur randomly and with no apparent cause and are termed sporadic. However, in several cases the syndrome appears to be inherited from a parent, supporting a role for genetics in the cause of Kabuki syndrome. Scientists hypothesize that an unidentified genetic abnormality that causes Kabuki syndrome is transmitted as an autosomal dominant trait. With an autosomal dominant trait, only one abnormal gene in a gene pair is necessary to display the disease, and an affected individual has a 50% chance of transmitting the gene and the disease to a child.
Demographics
Kabuki syndrome is a rare disorder with less than 200 known cases worldwide, but the prevalence of the disease may be underestimated as only a handful of physicians have first-hand experience diagnosing children with Kabuki syndrome. Kabuki syndrome appears to be found equally in males and females. Earlier cases were reported in Japanese children but the syndrome is now known to affect other racial and ethnic groups.
Theoretical mathematical models predict that the incidence of Kabuki syndrome in the Japanese population may be as high as one in 32,000.
Signs and symptoms
The signs and symptoms associated with Kabuki syndrome are divided into cardinal symptoms (i.e. those that are almost always present) and variable symptoms (those that may or may not be present). The cardinal and variable signs and symptoms of Kabuki syndrome are summarized in the table below.
Diagnosis
The diagnosis of Kabuki syndrome relies on physical exam by a physician familiar with the condition and by radiographic evaluation, such as the use of x rays or ultrasound to define abnormal or missing structures that are consistent with the criteria for the condition (as described above). A person can be diagnosed with Kabuki syndrome if they possess characteristics consistent with the five different groups of cardinal symptoms: typical face, skin-surface abnormalities, skeletal abnormalities, mild to moderate mental retardation, and short stature.
Although a diagnosis may be made as a newborn, most often the features do not become fully evident until early childhood. There is no laboratory blood or genetic test that can be used to identify people with Kabuki syndrome.
Treatment and management
There is no cure for Kabuki syndrome. Treatment of the syndrome is variable and centers on correcting the different manifestations of the condition and on strategies to improve the overall functioning and quality of life of the affected individual.
For children with heart defects, surgical repair is often necessary. This may take place shortly after birth if the heart abnormality is life threatening, but often physicians will prefer to attempt a repair once the child has grown older and the heart is more mature. For children who experience seizures, lifelong treatment with anti-seizure medications is often necessary.
Children with Kabuki syndrome often have difficulties feeding, either because of mouth abnormalities or because of poor digestion. In some cases, a tube that enters into the stomach, is placed surgically in the abdomen and specially designed nutritional liquids are administered through the tube directly into the stomach.
People with Kabuki syndrome are at higher risk for a variety of infections, most often involving the ears and the lungs. In cases such as these, antibiotics are given to treat the infection, and occasionally brief hospital stays are necessary. Most children recover from these infections with proper treatment.
Nearly half of people affected by Kabuki syndrome have some degree of hearing loss. In these individuals, formal hearing testing is recommended to determine if they might benefit from a hearing-aid device. A hearing aid is a small mechanical device that sits behind the ear and amplifies sound into the ear of the affected individual. Occasionally, hearing loss in individuals with Kabuki syndrome is severe, approaching total hearing loss. In these cases, early and formal education using American Sign Language as well as involvement with the hearing-impaired community, schools, and enrichment programs is appropriate.
Children with Kabuki syndrome should be seen regularly by a team of health care professionals, including a primary care provider, medical geneticist familiar with the condition, gastroenterologist, and neurologist. After growth development is advanced enough (usually late adolescence or early adulthood), consultation with a reconstructive surgeon may be of use to repair physical abnormalities that are particularly debilitating.
During early development and progressing into young adulthood, children with Kabuki syndrome should be educated and trained in behavioral and mechanical methods to adapt to any disabilities. This program is usually initiated and overseen by a team of health care professionals including a pediatrician, physical therapist, and occupational therapist. A counselor specially trained to deal with issues of disabilities in children is often helpful is assessing problem areas and encouraging healthy development of self-esteem. Support groups and community organizations for people with disabilities often prove useful to the affected individuals and their families, and specially equipped enrichment programs should be sought. Further, because many children with Kabuki syndrome have poor speech development, a consultation and regular session with a speech therapist is appropriate.
Prognosis
The abilities of children with Kabuki syndrome vary greatly. Most children with the condition have a mild to moderate intellectual impairment. Some children will be able to follow a regular education curriculum, while others will require adaptations or modifications to their schoolwork. Many older children may learn to read at a functional level.
The prognosis of children with Kabuki syndrome depends on the severity of the symptoms and the extent to which the appropriate treatments are available. Most of the medical issues regarding heart, kidney or intestinal abnormalities arise early in the child's life and are improved with medical treatment. Since Kabuki syndrome was discovered relatively recently, very little is known regarding the average life span of individuals affected with the condition, however, present data on Kabuki syndrome does not point to a shortened life span.
Resources
BOOKS
Behrman, R.E., ed. Nelson Textbook of Pediatrics. Philadelphia: W.B. Saunders, 2000.
PERIODICALS
Kawame, H. "Phenotypic Spectrum and Management Issues in Kabuki Syndrome." Journal of Pediatrics 134(April 1999): 480-485.
Mhanni, A.A., and A.E. Chudley. "Genetic Landmarks Through Philately—Kabuki Theater and Kabuki Syndrome." Clinical Genetics 56(August 1999): 116-117.
ORGANIZATIONS
CardioFacioCutaneous Support Network. 157 Alder Ave., McKee City, NJ 08232. (609) 646-5606.
Kabuki Syndrome Network. 168 Newshaw Lane, Hadfield, Glossop, SK13 2AY. UK 01457 860110. <http://www.ksn-support.org.uk>.
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>.
WEBSITES
"Entry 147920: Kabuki Syndrome." OMIM—Online Mendelian Inheritance in Man. <http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=47920>.
Oren Traub, MD, PhD