Extremely rare genetic condition said to affect only some 25 children in the United States, though it is possible that many cases are not properly diagnosed.

The condition was first described in a boy seen at the Boston Floating Hospital (1973) and in a patient at the Harbor General Hospital in Torrance, California (1975), hence the unusual name, which is a blend of the names of the two hospitals.

These people are quite short, with delays of bone development; there are delays of expressive language development (that is, these children understand language, but have difficulty speaking), although motor development is normal; their faces are somewhat triangular, and they may have very thin lips. Intelligence may develop well, however, resulting in an adult with only moderately retarded intelligence.

There is no treatment for Floating Harbor Syndrome, though growth hormone has been used with good effect to accelerate growth. Left alone, these people have very short stature.

The cause of the condition is unknown; however it is suspected to be an autosomal dominant mutation – that is, a random mutation in the genotype of the affected individual. As of now, there is no way to diagnose the condition before birth. The precise location of the mutation is unknown.

Lacombe et al. (1995) (see citation below) reported a case where the father was 54 years old and the mother 41. The child's growth was delayed throughout infancy, though she crawled and walked at the usual ages. She had a triangular face, with thin lips. At the age of 7 years and 9 months, she had the bone age of a 3-year-old. The mother was quite short (138 cm), mildly retarded, and her face looked like her daughter's which caused the researchers to conjecture that the condition had been inherited from the mother.

Usually, however, there is no pattern of inheritance, and other children in the family are normal.

See Lacombe, D.; Patton, M. A.; Elleau, C.; Battin, J. : Floating-Harbor syndrome: description of a further patient, review of the literature, and suggestion of autosomal dominant inheritance. Europ. J. Pediat. 154: 658-661, 1995.