Björnstad syndrome is an extremely rare inherited disorder characterized by the presence of abnormally flattened, twisted hair shafts (pili torti) and, in most cases, deafness (sensorineural hearing loss). Hearing loss typically affects both ears (bilateral). Individuals with this disorder usually have dry, fragile, lusterless, and/or coarse scalp hair as well as areas of patchy hair loss (alopecia). Both autosomal dominant and recessive inheritance have been reported in the medical literature.
Björnstad syndrome is an extremely rare inherited disorder characterized by the presence of hair shafts that are abnormally flattened and twisted (pili torti). Individuals with this disorder may usually have dry, fragile, lusterless, and/or coarse scalp hair. When studied under an electron microscope, hair shafts from the scalp appear flattened and/or twisted (torti) at regular intervals. This twisting causes the hair to be brittle and dry. Body hair may exhibit the same characteristic twisting (pili torti) as scalp hair. In addition, in some cases, patchy areas of hair loss (alopecia) may be apparent on the scalp as well as other areas of the body. However, the eyebrows and eyelashes are typically not affected.
In addition, most individuals with Björnstad syndrome experience deafness due to an impaired ability of the auditory nerves to transmit sensory input to the brain (sensorineural hearing loss). When sensorineural deafness is present in such cases, it is apparent at birth (congenital) or within the first year of life. As an affected child ages, deafness may lead to speech difficulties.
Underdevelopment of the ovaries of affected females or the testes of affected males (hypogonadism) has occurred in association with Björnstad syndrome. Symptoms associated with this finding may include a delay in the development in secondary sexual characteristics (e.g., breast development and characteristic hair growth). The association of twisted hair, sensorineural deafness, and hypogonadism may be a clinical syndrome that is distinct from Björnstad syndrome.
Björnstad syndrome is thought to be inherited as an autosomal dominant or recessive trait. Genetic diseases are determined by two genes, one received from the father and one from the mother.
Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%.
Researchers have determined that some cases of Björnstad syndrome occur because of disruptions or changes (mutations) of an, as yet, unidentified gene is located on the long arm (q) of chromosome 2 (2q34-q36). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Pairs of human chromosomes are numbered from 1 through 22, and an additional 23rd pair of sex chromosomes which include one X and one Y chromosome in males and two X chromosomes in females. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 2q34-q36″ refers to bands 34-36 on the long arm of chromosome 2. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Some researchers believe that Björnstad syndrome may be the result of several different genes or combinations of several genes (heterogeneous). In addition, some researchers suspect that the gene(s) responsible for this disorder may manifest themselves in different ways (pleiotrophic). For example, some researchers believe that sensorineural hearing loss may be a pleiotrophic manifestation that may not always occur in association with this disorder.
Families of affected individuals have not been studied completely; therefore, it is not possible to evaluate whether Björnstad syndrome may also be inherited as an X-linked disorder (carried by females).
The association of twisted hair, deafness, and hypogonadism may be a clinical syndrome that is distinct from Björnstad syndrome and may be inherited as an autosomal recessive trait.
Björnstad syndrome is an extremely rare disorder that was first described in 1965. In theory, it affects males and females in equal numbers. However, in observed cases, more females than males have been identified. More than 30 cases have been reported in the medical literature.
The diagnosis of Björnstad Syndrome may be suspected by the finding of twisted hair (i.e., pili torti), which may be obvious at birth. The diagnosis is confirmed by examination of hair shafts from affected individuals under an electron microscope, demonstrating characteristic twisting of the hair shafts at regular intervals. Since the presence of this hair abnormality is suggestive of Björnstad Syndrome, all infants with this finding should be evaluated for possible nerve deafness. Sensorineural deafness may be confirmed through a variety of specialized hearing (auditory) tests.
The treatment of Björnstad Syndrome is directed toward the specific symptoms that are apparent in each child. Treatment may require the skills of a team of specialists. Pediatricians, specialists who assess and treat hearing loss (audiologists), and physicians who specialize in diagnosing and treating disorders involving the skin (dermatologists) may coordinate their efforts to ensure the comprehensive, systematic treatment of affected children.
The treatment of patchy hair loss (alopecia) may include the use of wigs and/or other hair replacement therapies. Sensorineural deafness should be assessed and treated as early as possible to help avoid possible speech problems as an affected child ages.
Early intervention is important in ensuring that children with Björnstad Syndrome reach their potential. Services that may be beneficial may include special remedial education, special services for children with congenital sensorineural deafness, and other medical, social, and/or vocational services.
Genetic counseling may be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.
Research on genetic disorders and their causes is ongoing. The National Institutes of Health (NIH) is sponsoring the Human Genome Project which is aimed at mapping every gene in the human body and learning why they sometimes malfunction. It is hoped that this new knowledge will lead to prevention and treatment of genetic and familial disorders in the future.
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McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:262000; Last Update: 3/13/01.