GENE GUIDE

SRCAP-Related Syndrome

This guide is not meant to take the place of medical advice. Please consult with your doctor about your genetic results and health care choices. This Gene Guide was last updated in 2026. As new information comes to light with new research we will update this page. You may find it helpful to share this guide with friends and family members or doctors and teachers of the person who has SRCAP-Related Syndrome.
a doctor sees a patient

SRCAP-related syndrome is also called Floating-Harbor syndrome or developmental delay, hypotonia, musculoskeletal defects, and behavioral abnormalities (DEHMBA). For this webpage, we will be using the name SRCAP-related syndrome to encompass the wide range of variants observed in the people identified.

SRCAP-related syndrome happens when there are changes to the SRCAP gene. These changes can keep the gene from working as it should.

Key Role

The SRCAP gene plays a key role in cell growth.

Symptoms

Because the SRCAP gene is important for brain activity, many people who have SRCAP-related syndrome have:

  • Intellectual disability
  • Language delay
  • Delay in bone growth that ends between ages 6 and 12
  • Short height
  • Skeletal defects
  • Autism or features of autism
  • Low muscle tone
  • Constipation
  • Gastroesophageal reflux disease (GERD)
  • Attention-deficit/hyperactivity disorder (ADHD)
  • Seizures

SRCAP-related syndrome is a genetic condition, which means that it is caused by variants in genes. Our genes contain the instructions, or code, that tell our cells how to grow, develop, and work. Every child gets two copies of the SRCAP gene: one copy from their mother’s egg, and one copy from their father’s sperm. In most cases, parents pass on exact copies of the gene to their child. But the process of creating the egg or sperm is not perfect. A change in the genetic code can lead to physical issues, developmental issues, or both. 

Sometimes a spontaneous variant happens in the sperm, egg or after fertilization. When a brand new genetic variant happens in the genetic code is called a ‘de novo’ genetic variant. The child is usually the first in the family to have the genetic variant.

De novo variants can take place in any gene. We all have some de novo variants, most of which don’t affect our health. But because SRCAP plays a key role in development, de novo variants in this gene can have a meaningful effect. 

Research shows that SRCAP-related syndrome is often the result of a de novo variant in SRCAP. Many parents who have had their genes tested do not have the SRCAP genetic variant found in their child who has the syndrome. In some cases, SRCAP-related syndrome happens because the genetic variant was passed down from a parent.

Autosomal dominant conditions

SRCAP-related syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in SRCAP they will likely have symptoms of SRCAP-related syndrome. For someone with an autosomal dominant genetic syndrome, every time they have a child there is a 50 percent chance they pass on the same genetic variant and a 50 percent chance they do not pass on the same genetic variant.

Autosomal Dominant Genetic Syndrome

GENE / gene
GENE / gene
Genetic variant that happens in sperm or egg, or after fertilization
GENE / gene
Child with de novo genetic variant
gene / gene
Non-carrier child
gene / gene
Non-carrier child

Why does my child have a change in the SRCAP gene?

No parent causes their child’s SRCAP-related syndrome. We know this because no parent has any control over the gene changes that they do or do not pass on to their children. Please keep in mind that nothing a parent does before or during the pregnancy causes this to happen. The gene change takes place on its own and cannot be predicted or stopped.

Each family is different. A geneticist or genetic counselor can give you advice on the chance that this will happen again in your family.

The risk of having another child who has SRCAP-related syndrome depends on the genes of both biological parents. 

  • If neither biological parent has the same genetic variant found in their child, the chance of having another child who has the syndrome is on average 1 percent. This 1 percent chance is higher than the chance of the general population. The increase in risk is due to the very unlikely chance that more of the mother’s egg cells or the father’s sperm cells carry the same genetic variant. 
  • If one biological parent has the same genetic variant found in their child, the chance of having another child who has the syndrome is 50 percent. 

For a symptom-free brother or sister of someone who has SRCAP-related syndrome, the sibling’s risk of having a child who has SRCAP-related syndrome depends on the sibling’s genes and their parents’ genes. 

  • If neither parent has the same genetic variant causing SRCAP-related syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit SRCAP-related syndrome. 
  • If one biological parent has the same genetic variant causing SRCAP-related syndrome, the symptom-free sibling has a 50 percent chance of also having the same genetic variant. If the symptom-free sibling has the same genetic variant, their chance of having a child who has the genetic variant is 50 percent. 

For a person who has SRCAP-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2026, over 100 people in the world with changes in the SRCAP gene have been described in medical research. The first case of SRCAP-related syndrome was described in 2012. Scientists expect to find more people who have the syndrome as access to genetic testing improves.

People with SRCAP-related syndrome may look different. Appearance can vary and can include, but is not limited to, these features:

  • Triangular face
  • Deep-set eyes
  • Short distance between the upper lip and nose
  • Wide mouth
  • Thin line of the upper lip
  • Long nose with narrow bridge
  • Broad nose tip
  • Low-set ears

Scientists and doctors have only just begun to study SRCAP-related syndrome. At this point, there are no medicines designed to treat the syndrome. A genetic diagnosis can help people decide on the best way to track the condition and manage therapies. Doctors can refer people to specialists for:

    • Physical exams and brain studies
    • Genetics consults
    • Development and behavior studies
    • Other issues, as needed

A developmental pediatrician, neurologist, or psychologist can follow progress over time and can help:

    • Suggest the right therapies. This can include physical, occupational, speech, or behavioral therapy.
    • Guide individualized education plans (IEPs).

Specialists advise that therapies for SRCAP-related syndrome should begin as early as possible, ideally before a child begins school.

If seizures happen, consult a neurologist. There are many types of seizures, and not all types are easy to spot. To learn more, you can refer to resources such as the Epilepsy Foundation’s website: www.epilepsy.com/learn/types-seizures.

This section includes a summary of information from major published articles. It highlights how many people have different symptoms. To learn more about the articles, see the Sources and references section of this guide.

Learning and Speech

Most people with SRCAP-related syndrome had developmental delay or intellectual disability, and speech delay or impairment. A regression of skills was not typical for people with SRCAP-related syndrome.

  • 41 out of 48 people had developmental delay or intellectual disability (85 percent)
  • 33 out of 33 people had speech delay or impairment (100 percent)

Behavior

Many people with SRCAP-related syndrome had behavioral issues, such as autism or features of autism, attention-deficit/hyperactivity disorder (ADHD), aggressive behavior, anxiety, and oppositional behaviors. Researchers have suggested that behavioral challenges improve in adulthood.

Brain

A few people with SRCAP-related syndrome had seizures or brain changes seen on magnetic resonance imaging (MRI).

  • 28 out of 87 people had seizures (32 percent)

Growth

People with SRCAP-related syndrome had skeletal defects, dental issues, and short height. Children might be born within the typical range for height and weight at birth, but the growth rate slows down in infancy due to lower levels of growth hormone. Delay in bone age was very common, with children usually catching up between the ages of 6 to 12 years old. Average adult height was 4 feet 7 inches to 5 feet 1 inch (140 cm to 155 cm). Some people went through puberty at an earlier than average age.

  • 23 out of 26 people had skeletal defects (89 percent)
  • 25 out of 35 people had dental issues (71 percent)
  • 38 out of 38 people had short height (100 percent)

Vision and hearing

People with SRCAP-related syndrome had vision issues, including farsightedness (hyperopia) and crossed eyes (strabismus). Some people had hearing loss.

Where can I find support and resources?

Unique

Geisinger Developmental Brain Disorder Gene Database

Simons Searchlight

Simons Searchlight is an online international research program, building an ever growing natural history database, biorepository, and resource network of over 175 rare genetic neurodevelopmental disorders. By joining their community and sharing your experiences, you contribute to a growing database used by scientists worldwide to advance the understanding of your genetic condition. Through online surveys and optional blood sample collection, they gather valuable information to improve lives and drive scientific progress. Families like yours are the key to making meaningful progress. To register for Simons Searchlight, go to the Simons Searchlight website at www.simonssearchlight.org and click “Join Us.”

Sources and references

The content in this guide comes from published studies about SRCAP-related syndrome. Below you can find details about each study, as well as links to summaries or, in some cases, the full article.

  • Dobrzynski, W., Stawinska-Dudek, J., Moryto, N., Lipka, D., & Mikulewicz, M. (2024). Floating-Harbor syndrome: A systematic literature review and case report. Journal of Clinical Medicine, 13(12), 3435. doi:10.3390/jcm13123435
  • He, Q., Deng, Y., Xu, L., Xu, Z., Ding, Y., & Wu, M. (2025). Recombinant human growth hormone treatment of Floating-Harbor syndrome: A case report and literature review. BMC Pediatrics, 25(1), 97. doi:10.1186/s12887-025-05437-7
  • Jeon, J., Noh, E. S., & Hwang, I. T. (2026). Floating-Harbor syndrome in a Korean patient with short stature and early puberty: A case report. Journal of Clinical Research in Pediatric Endocrinology, 18(1), 176-180. doi:10.4274/jcrpe.galenos.2024.2023-12-12
  • Liang, X. Y., Meng, X. H., Wu, W. C., Guo, J., Luo, S., Wang, P. Y., Zhang, D. M., Lin, Z. S., Liang, J. J., … & Liao, W. P. (2026). De novo SRCAP variants cause developmental and epileptic encephalopathy and the phenotypic spectrum. Epilepsia, 67(2), 846-861. doi:10.1111/epi.18695
  • Nowaczyk, M. J. M., Nikkel, S. M., & White, S. M. SRCAP-related Floating-Harbor syndrome. 2025 Apr 10. In: Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Available from: https://www.ncbi.nlm.nih.gov/books/NBK114458/
  • Yang, W., Li, R., Chen, C., Yan, J., & Sang, Y. (2026). Pediatric floating-harbor syndrome: Clinical features and treatment outcomes in a cohort of Chinese children. European Journal of Pediatrics, 185(1), 52. doi:10.1007/s00431-025-06681-w