Floating Harbor Syndrome

Floating-Harbor syndrome is a disorder involving short stature, slowing of the mineralization of the bones (bone age), delayed speech development, and characteristic facial features.

In 1973, Pelletier and Feingold described a young male who was seen at the Boston Floating Hospital with short stature, delayed speech and unusually triangular facial appearance. A further report of a similar case was published by Leisti et al. who had seen their patient at the Harbor General Hospital,  Torrance, California. they suggested the term Floating Harbor Syndrome.

There are around 100 recognised individuals with a diagnosis of Floating Harbor Syndrome worldwide, including the UK, Australia, Canada, USA, Italy and many more.

Information relating to this syndrome has until recently been very limited. More data is being made available and more easily accessible on the Internet. Please keep checking back for updates as we get them. There are a whole range of areas of physical and cognitive delays associated with Floating Harbor Syndrome and we try to cover as much as possible throughout this site. It is not a case of one size fits all, and you may recognise some symptoms and not others.

Everyone is different, therefore parents should talk to their children’s physician and medical team about their specific case, associated symptoms and overall prognosis. It is vital however that the FHS child is monitored closely by specialized professionals throughout childhood, and parents are given every opportunity to share the experiences of the child from their perception. Working in partnership will only help the FHS child in future

Several factors including the small number of identified cases, the lack of large clinical studies, and the possibility of other genes influencing the disorder prevent physicians from developing a complete picture of associated symptoms and prognosis, therefore, it is important to note that affected individuals may not have all of the symptoms discussed below. 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 may be below average height for their age (short stature), and among the shortest 5 percent of their age group.

Children with FHS may exhibit behavioural abnormalities including hyperactivity, impulsivity, short attention span, aggression, anxiousness, however some children can also be placid, disinterested and loving to be around.

Some of the obsessive behaviours such as repeated skin picking and destructive moods are also reported.

A common concern for care givers is FHS individuals have a high pain threshold. This is consistent with sensory disorders.

Education for children with FHS is one of the big concerns for parents and the information provided here as a guidance for teachers, should be adhered to as much as possible; this is aimed to help the child have a positive learning experience. Click Here to view.

Speech and language deficits are common in children with FHS. Expressive language deficits are most common and often most severely affected. Expressive language is the ability of a person to ‘output’ language or how people express themselves such as through speech or writing. It also encompasses the use of gestures and facial expressions. Some affected children also have receptive language deficits, in which they are unable to understand words and gestures. Affected individuals may have difficulty speaking (dysarthria) and exhibit a distinct, high-pitched nasally voice. In some cases, speech may be absent. Children may be described as having verbal dyspraxia, which refers to the difficulty or inability to coordinate the precise movements required to produce clear speech despite the absence of damage to the nerves or muscles. The severity of expressive and receptive language abnormalities can vary widely.

Intellectual disability that is typically mild to moderate in degree has been reported. Learning disabilities are common as well.

This can affect their comprehension therefore constant repetition is required to reinforce what they learn. Their development of motor skills, such as sitting and crawling, can be similar to that of other children their age.

In addition to growth deficiencies, children with FHS have a delay in bone aging in the first decade of life, which means that the rate of growth and calcification of the bones is slower than normal.

Infants and children with FHS have distinctive facial features including a triangularly-shaped face; low-set ears; deep-set eyes with abnormally long eyelashes; thin lips; a broad, linear mouth; a prominent, triangular-shaped nose that is narrow at the root and broadens at the base; the bottom of the sheet of cartilage and bone (nasal septum) that separates the right and left nostrils (columella) may be low-hanging; the nostrils are large; and the groove that runs from the nose to the upper lip (philtrum) is short. These facial characteristics are the most distinctive features of FHS. Although they may change as an affected individual ages, the key features remain constant.

It has been recorded that some children with a diagnosis of Floating Harbor Syndrome also have Isodicentric chromosome 15 syndrome, which is a developmental disorder with a broad spectrum of features. The signs and symptoms vary among affected individuals.

Poor muscle tone is commonly seen in individuals with isodicentric chromosome 15 syndrome and contributes to delayed development and impairment of motor skills, including sitting and walking.

Affected individuals exhibit various skeletal malformations including short fingers and toes (brachydactyly); broad fingertips that give the appearance of clubbing; short, broad thumbs; and prominent joints. The pinkies may be fixed or ‘locked’ in a bent position (clinodactyly). Some individuals may have abnormalities of the collarbones (clavicles) including underdevelopment (hypoplasia) of the collarbone or the development of a ‘false joint’ (pseudoarthrosis). A false joint is a bony structure that usually develops at the site of a poorly united fracture that allows abnormal movement of the affected bones.

Dental abnormalities are also common with FHS and it is of extreme importance that you should discuss your child’s background before any treatment starts. Dental anomalies may also occur including extra (supernumerary) teeth, delayed loss of primary (“baby”) teeth, abnormally small teeth (microdontia), and malocclusion, a condition in which the upper teeth are improperly positioned in relation to the lower teeth.

Additional symptoms have been reported in individuals with FHS including short bones in the hands (metacarpals); the presence of 11 pairs of ribs instead of 12; malformed (dysplastic) hips; abnormal curvature of the spine (kyphoscoliosis); seizures; backflow or leakage of the contents of the stomach into the oesophagus (gastroesophageal reflux); farsightedness (hyperopia); crossed eyes (strabismus); recurrent middle ear infections (otitis media); and conductive hearing loss. Conductive hearing loss occurs when there is impaired transmission of sound from the outer or middle ear to the inner ear. The individual will shout and talk loudly. Normal hearing tests are not appropriate to pick up the affected areas, again, inform your physician of the above impaired transmission of sound. In some cases, affected individuals may exhibit kidney abnormalities such as cysts on the kidneys or swelling (distension) of the kidneys due to the abnormal accumulation of urine (hydronephrosis). Hydronephrosis develops because of blockage within the urinary tract that prevents urine from being evacuated through the bladder. In some cases, there may be absence of the kidneys (agenesis).

In some cases, the onset of puberty may occur earlier than normal(Precocious puberty). Males may have undescended testicles (cryptorchidism) and hypospadias, a condition in which the tube that is connected to the bladder and discharges urine from the body (urethra) opens on the underside of the penis instead of the tip.

Other conditions that have been reported in individuals with FHS include Coeliac disease, congenital heart defects, mild underactivity of the thyroid (hypothyroidism), and, in adulthood, high blood pressure (hypertension).

Floating-Harbor syndrome is caused by a mutation in the SRCAP gene. Genes provide instructions for creating proteins that play a critical role in many functions of the body. When a mutation of a gene occurs, the protein product may be faulty, inefficient, or absent. Depending upon the functions of the particular protein, this can affect many organ systems of the body.

Investigators have determined that the SRCAP gene is located on the short arm (p) of chromosome 16 (16p11). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered.

In FHS, mutations in the SRCAP gene often occur as a new (sporadic or de novo) mutation, which means that in nearly all cases the gene mutation has occurred at the time of the formation of the egg or sperm for that child only, and no other family member will be affected. There are no silent carriers of FHS (i.e. if one carries a mutation in SRCAP, he/she will show signs of FHS).

Although most cases are due to sporadic mutations, dominant inheritance (where a trait is transmitted from either an affected mother or father to a child) has been documented in a few families. Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy. The risk is the same for males and females.

The SRCAP gene creates (encodes) a protein that has several functions in the body. This protein is a cofactor (i.e. a substance required for a protein’s biological activity) for the CREB-binding protein (CREBBP). Mutations in the gene that produces CREB-binding protein cause Rubinstein-Taybi syndrome, a rare disorder with many overlapping symptoms to FHS.

We constantly strive to update information as and when it is available, therefore if you have anything to add, please contact us.

 

 

 

24 thoughts on “Floating Harbor Syndrome

  1. Hy, my doughter have a Floating Harbor sindrome …. We live in Italy, if someone want to contact us it well be great. Thank you, happy Chrisymass! Monica and Shirley.

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  2. Hello we have a child with floating harbor syndrome and need some advice as the doctor has not heard of this before and suggested we google it for expert opinion hope you can help us understand what is wrong with our child?

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    • Hi Patricia, I have identical twin sons with FHS ,now 36 years of age and they both have scoliosis. Happy to chat further. We live in Western Australia. Funnily enough have just come back from a trip to Canada!

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  3. A great idea to include relevant info such as Scoliosis. Might also be an idea to have an area where all the other signs of FHS can be added. Our list is very long indeed. Main concern is letting everyone know about the risk to kidney function due to polycystic kidney disease. So please one and all, check your blood pressure regularly and get kidney function tests done as well. Our sons were diagnosed after 35 years of intense searching ( as you can imagine a very long story here) but in the meantime, as we did not know about the diagnosis, their kidneys had been damaged . My best wishes to everyone. Regards, Noni

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  4. I meant to add that the section on Educating children with FHS is brilliant. If only we had that knowledge when our sons were in school. Another long story. But, what is great that even though school was a real challenge for them, once they left school things improved hugely. Perhaps less academic stress, developmental catch up, who knows ……. so hang on in there things do get better and continue to grow and develop in this important area.

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  5. Thanks Noni for your input. Would you like to use the the contact form and email ideas and your experiences? I have added FHS Stories and Associated Difficulties/Disorders headings – all we need to do now is start filling them up with relevant data.

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  6. Hello. My daughter is 31 years old tomorrow. We have an appointment with geneticist on 6 Jan next year at Guys Hospital. I am convinced Holly has FHS. Can tick most of symptoms. Some people disagree that I am digging this up again but I would like a diagnosis as her siblings are considering having children and may need screening (if possible) but the biggy is knowing what Holly may be susceptible to so that we may monitor and prevent any great ailments.
    It feels good to be able to communicate on familiar ground at last.
    Dawn

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    • Hullo Dawn. Oh this sounds so familiar. Took us 35 years to finally get a diagnosis for our identical twins. I understand fully the drive to find out as it is very important to know for many reasons. It is great that you have an appointment with a Geneticist as they will be able to help. Mind you, once we had the test it took 9 months to get the results. But no matter, we eventually had the answer to a very big mystery. Although we searched and searched for decades ( many appointments, overseas trips to see medicos etc etc) we found it on the internet ourselves !! Many happy birthday wishes to your daughter. I hope she has a lovely day. My kindest regards, Noni

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      • Good evening Noni

        Thank you for your reply. It is good to speak to some one that really does understand.
        Hollys mental age has been assessed as 2 years old which sounds a little more extreme than other FHS cases. She wears pads and her speech is limited to half a dozen words and those just the beginning of. She has on rare occasions said a whole word which raised my hopes but then never repeated. (Words were: aeroplane and Andrew (her brothers name) both were said absolutely perfectly.
        Her understanding of language is much better.
        All of the features /symptoms listed on this site are present in Hollys characteristics including dental abnormalities and the coeliac condition and all facial features.
        Motor skills were not as described here. Holly did not sit, crawl and walk as per her age group. This was much delayed. She also does not have scoliosis.
        It feels like I am asking you to confirm!! Sorry. So many unanswered questions.

        It sounds like you have been on quite a journey and at last you have an answer and you are able to address the kidney damage. It is a shame it wasn’t diagnosed much earlier and less damage done.
        I guess you should take some pride and consolation in the fact you had the energy and time to fight and find the answers. Many parents are too busy, tired and stressed to research and persevere to this end. And your achievements will go on to help others.

        How do they test for polycystic kidneys? What are the symptoms?
        Holly doesn’t cooperate at doctors or hospitals. I ask if she could be scanned when under anaesthetic for dental treatment but they just reply that it is a different department!

        The hospital have said she has polycystic ovaries! This was diagnosed after holly becoming quite hirsute around her chin and a blood test. Can’t scan as she doesn’t understand and cannot cooperate to have any tests.
        I am hoping our appointment in January will confirm FHS and further investigations will follow so that we know Holly is the healthiest Sean be.

        Thank you for taking the time to answer my email. Sorry for rambling

        Kindest regards
        Dawn

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      • How lovely to hear back from you Dawn. I get the feeling we could talk for hours. Do you have access to Skype? Then we could get the coffee or a wine and really get cracking on exchanging our stories ! If you are happy to email me Holly’s photo that sometimes can help in a diagnosis but that really is the medical professions job not mine, but I would love a photo. Happy to email you one of my guys, they would not mind at all. Just about to head off to the airport to pick up our daughter who is arriving from Detroit where she is studying her Doctorate in Speech Pathology. She is coming home for Christmas, so all very excited here.
        As far as the kidney function goes there are a few things that can help in a diagnosis rather than be scanned. One of the first things I noticed was an odor about the guys so got them to go to the GP who really had no idea. She did some blood tests which were abnormal but said they were OK. Then said one of them had high blood pressure after he went to see her with the flu. Once again said he was OK. I was not happy and was in the process of changing Dr’s when he got really sick, back pain (and both have very high pain thresholds) and was passing blood in his urine. Did not mess around then and off to emergency we went. That ended up in a 4 day stay in hospital and lots of tests. Official diagnosis was Adult Polycystic Autosomal Dominant Kidney Disease. This diagnosis made no sense to me as there was no family history as such. Hence our search intensified and in fact my daughter was then able to access a new data base through her new Uni and there it was FHS! Still remember so clearly seeing a photo of someone with FHS and they looked exactly like my sons. Surreal moment indeed.
        So having said all of that, perhaps a urine test if possible, a blood test if possible. And also check blood pressure if Holly would tolerate that being done. The blood pressure is probably the most telling one.
        Now I best go otherwise the poor gal will be wondering where her loving mother is after travelling from the opposite side of the world!
        Many blessings to you and your family for a wonderful Christmas Dawn. Love, Noni

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    • Hi and welcome Dawn. We hope that you can find the answers you seek. Well done for trying to do what you can to help, as any information the consultant can give you, may help other parents too.

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  7. Good evening Noni and any one that may be able to advise.

    I am due to go to the geneticist at Guys hospital in London.
    My daughters characteristics are: reflux, coeliac, dental abnormalities, district facial features, delayed growth, short stature, delayed expressive language, broad nose, thin lips, feeding difficulties, odd hyperkinetic behaviour, excessive body hair, LONG eyelashes (dead straight), delayed learning disability, short filtrum.
    about 10 years ago there was a meeting of geneticists where Hollys case was presented. They understood why FHS was being presented but knocked it out as Hollys learning ability was more extreme.

    I would like to know if I should ask for any particular tests. If there are any new cases with more extreme learning disabilities. Holly is 31 years old. She is doubly incontinent. Has no idea of danger. Her language comprehension is quite extensive but speech is limited to a dozen essential words and then only the beginning of the word.

    I will try to upload a picture of Holly

    Many thanks for any information you might think I may find useful

    Kindest regards
    Dawn

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    • Funny thing was that I was thinking about you so much today as I knew it was your special day tomorrow to see the Geneticist. I think the best thing is for me to email you directly a long list of our son’s medical history . There is always the possibility that Holly has 2 disorders among which FHS is one of them. In my line of work that is not uncommon. But it does cloud the picture making diagnosis’s even more difficult. I will get back to you as soon as I can. Lovely to hear from you Dawn and I do hope you have a really great 2016. Love, Noni

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  8. Hello, I have a daughter who is 13 with FHS. She was diagnosed age 3, but I had to go private to get the diagnosis as the doctors said she had failure to thrive and blamed me. She has had the test for the chromosome disorder and she has the mutation on 16p 11.2. She also has Autistic traits (and a brother with Aspergers Syndrome) but doctors won’t test for ASD as she already has the FHS diagnosis. There is a Facebook group Floating Harbor Syndrome Support group, members are from as she round the world but include quite as she round few of us from the UK.

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  9. Hi Christina. Thanks for your message. I am always in awe of what other families go through in getting a diagnosis. It can be an isolating journey indeed. And being blamed…. well, that is a horrible part that ,sad to say, a few of us have gone through. Autistic traits are certainly part of the FHS but there is nothing to suggest that one cannot have 2 separate diagnosis. I have seen that quite often in my profession. Not being sure of what supports there are in the UK it does make it difficult to offer advice. We have a great Autism Assoc. here in Western Australia and they can offer lots of information and support. Do you have a similar organisation in the UK? They could let you know all about options for testing. Plus the best ways of assisting your daughter to live and learn in her community etc. I can fully appreciate your concerns about testing for ASD as knowing as much as one can about our kids is the best way we can help them. Trouble is that there are all too often speed humps along the way. Does she have a great school/teachers who can instigate an assessment?
    Happy to chat anytime Christina. Love from over the seas, Noni

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