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Reviewed December 2012
What is Floating-Harbor syndrome?
Floating-Harbor syndrome is a disorder involving short stature, slowing of the mineralization of the bones (delayed bone age), delayed speech development, and characteristic facial features. The condition is named for the hospitals where it was first described, the Boston Floating Hospital and Harbor General Hospital in Torrance, California.
Growth deficiency in people with Floating-Harbor syndrome generally becomes apparent in the first year of life, and affected individuals are usually among the shortest 5 percent of their age group. Bone age is delayed in early childhood; for example, an affected 3-year-old child may have bones more typical of a child of 2. However, bone age is usually normal by age 6 to 12.
Delay in speech development (expressive language delay) may be severe in Floating-Harbor syndrome, and language impairment can lead to problems in verbal communication. Most affected individuals also have mild intellectual disability. Their development of motor skills, such as sitting and crawling, is similar to that of other children their age.
Typical facial features in people with Floating-Harbor syndrome include a triangular face; a low hairline; deep-set eyes; long eyelashes; a large, distinctive nose with a low-hanging separation (overhanging columella) between large nostrils; a shortened distance between the nose and upper lip (a short philtrum); and thin lips. As affected children grow and mature, the nose becomes more prominent.
Additional features that have occurred in some affected individuals include short fingers and toes (brachydactyly); widened and rounded tips of the fingers (clubbing); curved pinky fingers (fifth finger clinodactyly); an unusually high-pitched voice; and, in males, undescended testes (cryptorchidism).
How common is Floating-Harbor syndrome?
Floating-Harbor syndrome is a rare disorder; only about 50 cases have been reported in the medical literature.
What genes are related to Floating-Harbor syndrome?
Floating-Harbor syndrome is caused by mutations in the SRCAP gene. This gene provides instructions for making a protein called Snf2-related CREBBP activator protein, or SRCAP. SRCAP is one of several proteins that help activate a gene called CREBBP. The protein produced from the CREBBP gene plays a key role in regulating cell growth and division and is important for normal development.
Mutations in the SRCAP gene may result in an altered protein that interferes with normal activation of the CREBBP gene, resulting in problems in development. However, the relationship between SRCAP gene mutations and the specific signs and symptoms of Floating-Harbor syndrome is unknown. Rubinstein-Taybi syndrome, a disorder with similar features, is caused by mutations in the CREBBP gene itself.
Read more about the SRCAP gene.
Read more about Rubinstein-Taybi syndrome.
How do people inherit Floating-Harbor syndrome?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
Most cases of Floating-Harbor syndrome result from new mutations in the gene and occur in people with no history of the disorder in their family. However, in some cases an affected person inherits the mutation from one affected parent.
Where can I find information about diagnosis or management of Floating-Harbor syndrome?
These resources address the diagnosis or management of Floating-Harbor syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about Floating-Harbor syndrome?
You may find the following resources about Floating-Harbor syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for Floating-Harbor syndrome?
What if I still have specific questions about Floating-Harbor syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding Floating-Harbor syndrome?
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (7 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.