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Floating Harbor Syndrome (FHS)

Last updated Sept. 14, 2018

Approved by: Maulik P. Purohit MD MPH

Floating Harbor Syndrome (FHS) is a rare genetic disorder characterized by the presence of several physical and mental abnormalities. This unusually termed disorder is named after two hospitals where it was first identified and described - the Boston Floating Hospital, Massachusetts and Harbor General Hospital, California (both located in the US).

What are the other Names for this Condition? (Also known as/Synonyms)

  • FHS (Floating Harbor Syndrome)
  • FLHS (Floating Harbor Syndrome)
  • Pelletier-Leisti Syndrome

What is Floating Harbor Syndrome? (Definition/Background Information)

  • Floating Harbor Syndrome (FHS) is a rare genetic disorder characterized by the presence of several physical and mental abnormalities.
  • This unusually termed disorder is named after two hospitals where it was first identified and described - the Boston Floating Hospital, Massachusetts and Harbor General Hospital, California (both located in the US).
  • The exact cause of FHS is unknown and the presence of very few incidences (less than 50 cases reported worldwide, so far) has made it considerably difficult in collecting information, which could aid in treatment, or prevent its occurrence.
  • Symptomatic and supportive treatment is provided to individuals with the genetic condition, which could include therapy and surgical correction of defects.

Who gets Floating Harbor Syndrome? (Age and Sex Distribution)

  • The onset of signs and symptoms occurs during early childhood.
  • Floating Harbor Syndrome affects both male and female sex equally.
  • No ethnic or racial predilection has been noted.

What are the Risk Factors for Floating Harbor Syndrome? (Predisposing Factors)

Floating Harbor Syndrome is said to be inherited in an autosomal dominant manner. Individuals with a positive family history, have a higher risk of developing this disorder.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Floating Harbor Syndrome? (Etiology)

  • The exact cause of Floating Harbor Syndrome is unknown. Nevertheless, genetic mutations that alter original gene expressions, is the cause factor of the syndrome
  • Gene mutations can occur sporadically and randomly, thereby affecting or getting carried over to subsequent generations
  • It is thought that FHS is an autosomal dominant genetic condition. It has also been noted that the SRCAP gene undergoes mutations. This disrupts certain vital protein production that are responsible for regulating cell division and growth
  • However, there are many cases of FHS, with no family history of the condition

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Floating Harbor Syndrome?

Floating Harbor Syndrome is marked by the presence of 4 major distinctive features, which are the following:

  • Short statured individuals (considering their age), which may be evident even at birth
  • A considerably delayed bone growth
  • Difficulty and delay in expressing/saying simple words, though the child may understand them
  • Typical facial features of FHS, visible after the child reaches 3 years of age include:
    • Small and triangular face profile
    • Wide bulb-like nose
    • Wide-mouth with thin lips turned downwards
    • Small eyes appearing deeply set
    • A short neck

Apart from these, there are secondary signs and features that are noted in a few children. They mainly relate to growth deficiencies (which may be even prenatal), imbalanced development, and behavioral issues. Some of the vital organs, the nervous system, bones, and muscles, etc. are affected.

  • Heart problems (narrowing of the artery that feeds the lungs), kidney, genital problems, dental abnormalities, severe skin sensitivity to the sun
  • Excess body hair, long eyelashes
  • Gluten intolerance (related to celiac disease), frequent constipation, feeding difficulties
  • Small nails and fingers, additional thumb, curved fifth digit on the hand, loosened bones of the joints (joint laxity), abnormalities of the hip joint
  • Impaired intellectual development (slight mental retardation), learning disabilities, hyperactive behavior
  • Cataract and a high-pitched voice, are some of the other signs

How is Floating Harbor Syndrome Diagnosed?

The physician undertakes a detailed physical examination, with a study of the patient’s family medical history. The classic symptoms of Floating Harbor Syndrome may be observed.

Other signs and tests that are performed include:

  • X-ray studies to determine age of the bones
  • Many of the signs and presentations overlap with other disorders, such as Dubowitz Syndrome, Russell-Silver Syndrome, Three M Syndrome, etc. Hence, a differential diagnosis is required to eliminate them

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Floating Harbor Syndrome?

Complications that develop due to Floating Harbor Syndrome are linked to various physiological defects and growth deficiencies. These could include:

  • Feeding problems
  • Heart, lung, and vision defects
  • Speech impairment
  • Bone-related problems

How is Floating Harbor Syndrome Treated?

The treatment for individuals with Floating Harbor Syndrome is symptomatic and supportive. The disorder has no known cure. Hence, an individualized treatment is planned and provided, based on the specific conditions/complications that develop.

Some of the treatment methods are:

  • Correction of physical defects using surgical procedures (for dental, vision, and even cardiac abnormalities)
  • For improving motor skills and mental disabilities, special therapeutic treatment is provided (by speech, physical, and occupational therapists)
  • A good, healthy and nutritious diet with plenty of vitamins, water, and adequate rest/sleep, is recommended
  • For individuals, who are photosensitive to sunlight - wide-brimmed hats, sunglasses, and other sun-protective aids are recommended
  • Sometimes, the mental/emotional condition of the child may be fragile. For such cases supportive care is necessary
  • Keep your child informed of scheduled activities ahead of time, and plan for future activities. It is always better to establish a routine for the child and help them in following/adhering to the same

How can Floating Harbor Syndrome be Prevented?

  • Currently, there are no specific methods or guidelines to prevent Floating Harbor Syndrome genetic condition
  • Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Floating Harbor Syndrome? (Outcomes/Resolutions)

  • Floating Harbor Syndrome is a genetic disorder of unknown origin. The children may be affected to varying degrees of intensity
  • However, with constant care and support by families and the healthcare providers, and using medical aids, the affected individuals are able to manage their lives

Additional and Relevant Useful Information for Floating Harbor Syndrome:

There are voluntary organizations and support groups that provide help and support to the individuals and families of Floating Harbor Syndrome affected.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Dec. 15, 2013
Last updated: Sept. 14, 2018