In 1974, a patient seen at the Harbor General Hospital (Torrance, California, U.S.A.) was found to share an undiagnosed and astonishingly unique set of symptoms with a patient seen just one year earlier, at the Floating Hospital (Boston, U.S.A.).^1,2 These symptoms were recognised as belonging to a new disorder, which was named  Floating-Harbor Syndrome (FHS); this name, was derived from the hospitals at which the first two cases of the disorder were seen.^3,4,5 Since then, FHS has proven itself to be an extremely rare genetic disorder, with just over 100 cases ever having been reported.^6,7

FHS is caused by a mutation in the SRCAP gene of our DNA.^8,9 In simple terms, this means that FHS is caused by a change to a certain section of the chemical code in our cells. The code (DNA)  itself is a chemical containing the information necessary for our cells to build various proteins. Different sections (or genes) of DNA are responsible for creating different proteins, and a change in a particular gene may cause the specific subtype of proteins it is responsible for to be built incorrectly. Consequently, mutations can cause these altered proteins to fail in performing their usual roles within various body processes and/or structures.

In Fetal Alcohol Syndrome (FAS), this mutation is responsible for a number of symptoms, including delayed speech development, short height, and distinct facial features.^10,11,12 Since FHS is a congenital genetic condition ( a person is born with the condition), there is no ‘cure’, however, early intervention programs can play a vital role in dealing with some of the symptoms presented by FHS.⁷ Before this article commences in outlining these early intervention programs, it is vital to understand what exactly FHS ‘looks like’: 

Physical characteristics

There is a range of physical characteristics which may be associated with FHS:^{4,5,7,13,14,15,16,17,18,19,20,21,22,23}

Growth and development   

• Short height
• A short neck
• A broad chest
• Low birth weight
• Low birth length 
• Cryptorchidism; undescended testicles
• Hypospadias; where the opening of the urethra is located in the wrong part of the penis

Facial structure and features

• A triangular face
• Deep-set eyes
• Short philtrum (the vertical indentation in the middle area above the upper lip, which connects to the nose)
• A prominent nose with a broad tip
• A small head
• A bulging and narrow forehead 
• Wide columella (the bridge of tissue that separates the nostrils at the bottom of your nose)
• Long eyelashes
• Low set ears, rotated rearwards
• Broad mouth, sometimes with downturned corners
• Ear/skin tag
• Cleft lip/palate
• Incomplete folding of the ears
• Thin (upper) lip(s) 

Dental

• Macrodontia: some teeth growing more than they should
• Microdontia: some teeth growing less than they should
• Micrognathia: small lower jaw
• Malocclusion: misaligned teeth
• Oligodontia: absence of 6 or more teeth from birth

Other features

• Clinodactyly: An abnormally curved finger
• Syndactyly: webbed toes or fingers
• Brachydactyly: disproportionately short fingers or toes
• Hirsutism: Excessive hair growth in areas of the body where it's usually minimal
• Sparse hair
• Hip dysplasia 
• Heavy periods
• Nail clubbing
• Joint laxity/hypermobility
• Dystrophic toenail; discoloured, thickened or deformed toenail
• Delayed bone age
• Atrial septal effect (a hole between the chambers of the heart)
• Coeliac disease
• Abdominal distention (swelling)

Neuropsychological symptoms

Furthermore, there are a number of neurological issues which may affect someone with FHS:^4,13,23,24

Speech

• Delays in speech development
• Hypernasality
• Ankyloglossia; limited tongue mobility
• Apraxia of speech
• Problems with articulation
• Developmental aphasia

Behaviour

• Attention deficits
• Anxiety
• Depressive symptoms
• Loss of appetite
• Tantrums
• Impulsiveness

Others

• Seizures
• Impaired/delayed motor skills; this may also play a part in speech deficits
• Visuospatial impairment
• Visuoconstructive apraxia: difficulty in assembling objects, drawing, or copying designs
• Mild deficits in cognitive skills
• Impaired visual and verbal memory

Early intervention programs

It is important to understand that not all symptoms or characteristics of FHS can, or even need, to be addressed.  Early intervention programs are only possible in the event of an early diagnosis. This is particularly challenging since not only are some of FHS’s hallmark symptoms significantly less prominent and noticeable at younger ages  (for example, “the facial phenotype and speech or language disorders are more difficult to notice among young patients”)²⁵ but also FHS shares similarities to a number of other conditions. Therefore, the role of genetic testing in the  “early detection, diagnosis, and treatment of the FHS”²⁶ can not be understated. 

There are a number of early intervention programs which may play a relevant role in dealing with some of the symptoms of FHS. These may include “a comprehensive rehabilitation program, including cognition, fine motor training, behavioural strategies, language and speech [...] designed to improve patient functions. The rehabilitation program [would be] carried out by a multidisciplinary team of professionals including [a] child neuropsychiatrist, audiologist and phoniatrist, clinical psychologist, sociologist, speech and language therapist and neuropsychomotor therapist.”²⁷

Growth hormone therapy 

A number of scientifically documented cases describe growth hormone therapy (genotropin) as an effective treatment in combating the short stature caused by FHS.^{25,26,28,29,30} There is evidence that this treatment often results in both “an increase of height and growth velocity”.^29,31

Similarly, other cases described “an increase [...] in body weight”³¹ and bone age showing “near-normalisation”²⁸ subsequent to growth hormone therapy. 

However, “data on use of [Human Growth Hormone] in FHS are limited”^32, and in one instance, the therapy was discontinued after 2 years due to a poor response.³³ Additionally, other scientists have concluded that “short stature in patients with FHS cannot be attributed to GH deficiency alone”²⁹; other more comprehensive and effective treatments may yet be considered for combating short stature, specifically in FHS. Therefore, it is encouraged that patients should first be referred to an endocrinologist if they are considering human growth hormone (HGH) therapy.³²

 Moreover, undetected and untreated celiac disease can worsen the extent of short stature for individuals with FHS, and therefore, “anti-endomysial antibody testing is advisable”.²⁰

Speech therapy

Studies show that early intervention speech-language rehabilitation receptive and expressive language can significantly improve the language function of children over 3 years old.14, 20, 27 In one case, a 27-year-old individual primarily presented a “residual articulation disorder and hypernasality”, after benefitting from language rehabilitation from the age of 4 to 16 years.¹³ This was not the only case where “articulation improved after language therapy.”²⁶

Similarly, “communication rehabilitation with sign language”³² is not only mentioned as a recommended consideration for helping individuals with FHS, but its use has also been of immense help to parents.¹⁴

Aside from the benefits that speech-language brings to communication itself, there is a potential relationship between speech and literacy disorders and early intervention is said to be valuable in improving literacy outcomes for those with severe speech disorders.²⁰

Behaviour

Some individuals with FHS may benefit from “behavior management by a behavioral specialist/psychologist with consideration of medication as needed.”³² Documented cases evidenced treatment with Ritalin for attention deficit hyperactivity disorder (ADHD)and “assistive medication for OCD”.^{20, 22} Furthermore, in one case, it was suggested that attention training was essential for the patient’s rehabilitation program.²⁶

Orthodontics

“The orthodontic treatment of patients with Floating–Harbor syndrome does not differ from standard treatment methods in completely healthy people.”⁷ In one case report, the treatment plan included the installation of fixed braces and the extraction of a tooth.⁷ The writers of this report also recommended that older patients should “wear a fixed appliance to correct defects.”⁷

Others

Other interventional programs may include “special education, and vocational training to address developmental disabilities”.³² Also, a number of surveillance measures have been recommended:³²

• “Close monitoring of growth, especially in the first year”
• Annual ophthalmologic evaluation 
• Annual hearing screening
• Annual blood pressure measurement
• Annual assessment of renal function 
• “Sonographic evaluation for renal cysts in teenage/adult years” 

Summary

Floating-Harbor Syndrome (FHS) is a rare genetic disorder caused by a mutation in the SRCAP gene, affecting physical and neuropsychological development. Symptoms include short stature, distinct facial features, and speech delays. Although there is no cure, early intervention programs, including growth hormone therapy, speech therapy, and behavioral management, can improve outcomes. “With improvements in genetics and tailored medicine, there is fresh optimism that a better knowledge of FHS will result in more successful interventions, giving patients who have this condition a better future.”⁷

Frequently asked questions 

What is floating-harbor syndrome?

Floating-Harbor Syndrome (FHS) is a very rare genetic disorder first identified in the 1970s. It leads to a unique set of symptoms, including delayed speech development, short stature, and distinctive facial features.

How is floating-harbor syndrome inherited? 

Floating-Harbor Syndrome is usually caused by a new mutation in the SRCAP gene, which means it often occurs randomly and is not always inherited from a parent. However, in rare cases, it can be passed down from an affected parent to their child.

What are the key symptoms to look out for? 

Key symptoms of FHS include delayed speech development, short height, and specific facial features such as a triangular face, deep-set eyes, and a prominent nose. Other signs can include dental anomalies, attention deficits, and anxiety, as well as many others..

Can floating-harbor syndrome be cured?  

Currently, there is no cure for Floating-Harbor Syndrome. Treatment focuses on managing the symptoms and providing support to help individuals live a full life. This may include speech therapy, special education, and medical care for any associated health issues.

How can families support a child with floating-harbor syndrome? 

Families can support a child with FHS by working closely with healthcare professionals to address the child's specific needs. This may involve regular medical check-ups, speech therapy, and creating a supportive and understanding environment at home and school.