Floating–Harbor syndrome

Overview

Floating–Harbor Syndrome (FHS) is a rare genetic disorder characterized by distinctive facial features, delayed speech development, short stature, and skeletal abnormalities. The condition was first identified in the 1970s at the Boston Floating Hospital and Harbor General Hospital, hence the name. FHS affects both males and females and usually becomes apparent in early childhood. While most individuals have normal intelligence, learning difficulties and developmental delays are common.

Causes

Floating–Harbor Syndrome is caused by mutations in the SRCAP gene (Snf2-related CREBBP activator protein), which is located on chromosome 16p11.2. The SRCAP gene plays a role in chromatin remodeling and gene expression, particularly during early development. The condition follows an autosomal dominant inheritance pattern, meaning only one copy of the altered gene is sufficient to cause the disorder. In most cases, the mutation arises de novo (new in the affected individual) and is not inherited from a parent.

Symptoms

The symptoms of Floating–Harbor Syndrome can vary but often include a combination of the following:

Craniofacial Features

• Triangular face with a broad, low nasal bridge

• Deep-set eyes and long eyelashes

• Short philtrum and thin upper lip

• Prominent nose and low-set ears

Growth and Skeletal Abnormalities

• Short stature, often noticeable in early childhood

• Delayed bone age

• Brachydactyly (short fingers), particularly the fifth finger

Developmental and Cognitive Features

• Significant expressive speech delay

• Language development much more impaired than receptive ability

• Learning difficulties or mild intellectual disability in some individuals

Other Possible Features

• Behavioral problems, including attention deficit or social anxiety

• Hearing loss or frequent ear infections

• Dental anomalies

• Delayed puberty or hormonal irregularities

Diagnosis

Diagnosis of Floating–Harbor Syndrome is based on clinical features and confirmed by genetic testing. Key diagnostic steps include:

• Clinical examination: Recognition of characteristic facial features and short stature.

• Developmental assessment: Evaluation of speech, language, and cognitive development.

• Bone age studies: Radiographic imaging to assess skeletal maturity.

• Genetic testing: Identification of mutations in the SRCAP gene confirms the diagnosis.

Treatment

There is no cure for Floating–Harbor Syndrome, and treatment is supportive, focusing on managing symptoms and improving development. A multidisciplinary approach is often required, including:

• Speech therapy: Essential for improving expressive language skills.

• Educational support: Special education services tailored to learning needs.

• Growth monitoring: Endocrinology consultation if growth hormone therapy is considered.

• Behavioral therapy: To address attention, social interaction, or anxiety issues.

• Hearing support: Regular audiological assessments and interventions for hearing loss.

Prognosis

The prognosis for individuals with Floating–Harbor Syndrome is generally favorable, especially with early intervention and supportive therapies. While most individuals experience some level of developmental delay, many can lead relatively independent lives. Lifespan is not believed to be significantly affected. Long-term outcomes depend on the severity of symptoms, particularly cognitive and speech-related challenges, and the effectiveness of therapeutic interventions.