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Floating Harbor Syndrome

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Copyright 1993, 2000, 2004

Synonyms of Floating Harbor Syndrome

Disorder Subdivisions

General Discussion

Floating-Harbor syndrome (FHS) is an extremely rare disorder characterized by short stature, delayed language skills, and a triangular shaped face. A broad nose, deep-set eyes and a wide mouth with thin lips give an affected individual a distinct appearance. FHS was named after the hospitals at which the first two cases were seen: the Boston Floating Hospital and Harbor General Hospital in California. The cause of this disorder is not known.

Symptoms

Individuals with Floating-Harbor syndrome develop short stature with delayed bone growth, a delay in expressive language, and distinct facial features.

In some cases, delayed growth may occur before birth (prenatal growth retardation) resulting in low birth weight. Typically, growth deficiencies become apparent during the first year of life. Affected children develop short stature, usually below the 5th percentile. In addition to growth deficiencies, all children with FHS have a delay in bone aging, which means that the rate of growth and development of the bones is slower than normal. The limbs and trunk are in proportion, while the head may appear relatively large.

Delay in the acquisition of expressive language is found in all children with FHS. Some children may be delayed in their learning ability as well. Most children appear to be slightly behind in school but there have been no recorded cases of severe or even moderate retardation.

Distinctive facial features are another symptom of FHS. These features typically become apparent at the age of three or four years. The nose and nasal bridge are broad, and the mouth is wide with thin lips. The eyes are deeply set and the face appears small with a triangular shape. Eyelashes may be longer than normal, and there may be dental abnormalities.

Additional symptoms may be associated in some cases of FHS. These symptoms do not occur in all cases. Abnormal bending (clinodactyly) of the fifth finger, abnormally short fingers (brachydactyly), clubbing of the fingers and/or excessive body hair (hirsutism) have been found in some individuals with FHS.

An intestinal malabsorption disorder caused by intolerance to gluten (celiac sprue) has been found in several individuals with this disorder. (For more information on this disorder, choose "Celiac Sprue" as your search term in the Rare Disease Database).

An additional thumb, constipation and/or a narrowing of the opening of the right ventricle into the pulmonary artery (pulmonary stenosis) have also been found in several affected individuals. Abnormal placement of the urinary opening on the underside of the penis (hyposapdias), a distinct, high-pitched voice, a malformed (dysplastic) hip, and clouding of the lenses of the eyes (cataracts) may also occur.

Causes

The exact cause of Floating-Harbor syndrome is not known. Both males and females are affected. There have been no reported cases of recurrence within a family. It is thought that FHS may be a new dominant mutation. A mutation is an unusual change in genetic material that has occurred for no apparent reason (sporadically). The alteration changes the original expression of the gene. When a mutation occurs, it can be transmitted to future generations.

Affected Populations

Floating-Harbor syndrome is an extremely rare disorder that affects males and females in equal numbers. There have been approximately 20 cases of this disorder reported in the medical literature. It is thought that the incidence of this disorder may actually be higher because many cases go unrecognized.

FHS was first described in the medical literature in 1973.

Related Disorders

Symptoms of the following disorders can be similar to those of Floating- Harbor Syndrome. Comparisons may be useful for a differential diagnosis:

Dubowitz Syndrome is a rare disorder thought to be inherited as an autosomal recessive genetic trait. Symptoms of this disorder are apparent at birth. Short stature, dental abnormalities, low birth weight, and/or unusual facial features are characteristic of Dubowitz Syndrome. (For more information on this disorder, choose "Dubowitz Syndrome" as your search term in the Rare Disease Database.)

Russell-Silver Syndrome is a rare disorder commonly thought of as a type of dwarfism. People with this disorder are short with a small triangular- shaped face, and light brown spots on the skin. Developmental abnormalities, as well as abnormal curvature of the fifth finger, may also be present. The exact cause of Russell-Silver Syndrome is not known although some medical researchers believe it may be inherited as either an X-linked or dominant genetic trait with incomplete penetrance. (For more information on this disorder, choose "Russell-Silver Syndrome" as your search term in the Rare Disease Database.)

Three M Syndrome is a rare disorder characterized by low birth weight, short stature, narrow face, abnormal bending of the fingers (clinodactyly), and thin-slender long bones. The head appears to be large and the face has a triangular shape. A prominent mouth as well as a short neck are also features of this disorder. Three M Syndrome is inherited as an autosomal recessive genetic trait.

Standard Therapies

A diagnosis of Floating-Harbor syndrome may be made based upon a detailed clinical evaluation, a detailed patient history and identification of characteristic findings. X-ray studies (radiography) may reveal delayed bone age.

There is no specific treatment for FHS. Affected children will benefit from an educational environment that provides appropriate programs to assist their needs. Speech therapy as well as teachers trained to work with learning disabilities are beneficial.

Other treatment is symptomatic and supportive. Genetic counseling may be of benefit for affected individuals and their families.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com

Organizations related to Floating Harbor Syndrome

References

TEXTBOOK
Lubinsky MS. Floating Harbor Syndrome. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:195.

Thoene JG, ed. Physicians' Guide to Rare Diseases. Montvale, NJ: Dowden Publishing Company Inc; 1995:72-73.

JOURNAL ARTICLES
De Benedetto MS, et al. Floating-Harbor syndrome: case report and craniofacial phenotype characterization. Int J Paediatr Dent. 2004;14:208-13.

Selimoglu MA, et al. First Turkish patient with Floating-Harbor syndrome with additional findings: cryptorchidism and microcephaly. Yonsei Med J. 2004;45:334-6.

Ioan D, Fryns JP. Floating-Harbor syndrome in two sisters: autosomal recessive inheritance or germinal mosaicism? Genet Couns. 2003;14:431-3.

Rosen AC, et al. A further report on a case of Floating-Harbor Syndrome in a mother and daughter. J Clin Exp Neuropsychol. 1998;20:483-95.

Hersh JH, et al. Changing phenotype in Floating-Harbor syndrome. Am J Med Genet. 1998;76:58-61.

Midro AT, et al. Floating Harbor syndrome. Case report and further syndrome delineation. Ann Genet. 1997;40:133-38.

Fryns JP, et al. The Floating-Harbor syndrome: two affected siblings in a family. Clin Genet. 1996;50:217-19.

Davalos IP, et al. Floating-Harbor syndrome. A neuropsychological approach. Genet Couns. 1996;7:283-88.

Smeets E, et al. The Floating-Harbor syndrome: report of another patient and differential diagnosis with Shprintzen syndrome. Genet Couns. 1996;7:143-46.

Lazebnik N, et al. The floating harbor syndrome with cardiac septal defect. Am J Med Genet. 1996;66:300-02.

FROM THE INTERNET
McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No: 136140; Last Update:6/17/1998.

Report last updated: 2008/04/20 00:00:00 GMT+0