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Disease Profile

Jacobsen syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

JBS; Chromosome 11q deletion syndrome; Partial 11q monosomy syndrome


Blood Diseases; Chromosome Disorders; Congenital and Genetic Diseases;


Jacobsen syndrome is a condition characterized by the deletion of several genes on chromosome 11. Signs and symptoms vary among affected people but often include Paris-Trousseau syndrome (a bleeding disorder); distinctive facial features; delayed development of motor skills and speech; and cognitive impairment. Other features may include compulsive behavior; attention deficit-hyperactivity disorder (ADHD); congenital heart defects; short stature; and/or skeletal abnormalities. In most cases, the deletion that causes Jacobsen syndrome is not inherited and occurs randomly due to an error in cell division. In some cases, an affected person inherits the deletion from an unaffected parent with a balanced translocation. Treatment depends on the specific symptoms in each affected person.[1]


The signs and symptoms of Jacobsen syndrome can vary. Most affected people have delayed development of motor skills and speech; cognitive impairment; and learning difficulties. Behavioral features have been reported and may include compulsive behavior; a short attention span; and distractibility. Many people with the condition are diagnosed with attention deficit-hyperactivity disorder (ADHD). The vast majority of people with Jacobsen syndrome also have a bleeding disorder called Paris-Trousseau syndrome, which causes abnormal bleeding and easy bruising. [1]

People with Jacobsen syndrome typically have distinctive facial features, which include small and low-set ears; wide-set eyes (hypertelorism) with droopy eyelids (ptosis); skin folds covering the inner corner of the eyes; a broad nasal bridge; down-turned corners of the mouth; a thin upper lip; and a small lower jaw (micrognathia). Affected people often have a large head (macrocephaly) and a skull abnormality called trigonocephaly, giving the forehead a pointed appearance.[1]

Other signs and symptoms of the condition may include congenital heart defects; short stature; feeding difficulties in infancy; frequent ear and sinus infections; and skeletal (bone) abnormalities.[1]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Bone marrow hypocellularity
Bone marrow failure
Feeding difficulties in infancy
Global developmental delay
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Low platelet count
30%-79% of people have these symptoms
Abnormal form of the vertebral bodies
Anteverted nares
Nasal tip, upturned
Upturned nasal tip
Upturned nose
Upturned nostrils

[ more ]

Aplasia/Hypoplasia of the earlobes
Absent/small ear lobes
Absent/underdeveloped ear lobes

[ more ]

Aplasia/Hypoplasia of the eyebrow
Absence of eyebrow
Lack of eyebrow
Missing eyebrow

[ more ]

Attention deficit hyperactivity disorder
Attention deficit
Attention deficit disorder
Attention deficit-hyperactivity disorder
Attention deficits
Childhood attention deficit/hyperactivity disorder

[ more ]

Broad columella
Broad hallux phalanx
Broad bone of big toe
Wide bone of big toe

[ more ]

Undescended testes
Undescended testis

[ more ]

Downslanted palpebral fissures
Downward slanting of the opening between the eyelids
Eye folds
Prominent eye folds

[ more ]

Facial asymmetry
Asymmetry of face
Crooked face
Unsymmetrical face

[ more ]

Finger syndactyly
Frontal bossing
High forehead
Wide-set eyes
Widely spaced eyes

[ more ]

Long hallux
Long big toe
Long philtrum
Low-set, posteriorly rotated ears
Increased size of skull
Large head
Large head circumference

[ more ]

Cornea of eye less than 10mm in diameter
Missing ribs
Absent ribs
Decreased rib number

[ more ]

Pes planus
Flat feet
Flat foot

[ more ]

Premature birth
Premature delivery of affected infants
Preterm delivery

[ more ]

Drooping upper eyelid
Recurrent respiratory infections
Frequent respiratory infections
Multiple respiratory infections
respiratory infections, recurrent
Susceptibility to respiratory infections

[ more ]

Short neck
Decreased length of neck
Short nose
Decreased length of nose
Shortened nose

[ more ]

Short stature
Decreased body height
Small stature

[ more ]

Short toe
Short toes
Stubby toes

[ more ]

Smooth philtrum
Squint eyes

[ more ]

Toe clinodactyly
Toe syndactyly
Fused toes
Webbed toes

[ more ]

Ventricular septal defect
Hole in heart wall separating two lower heart chambers
5%-29% of people have these symptoms
Abnormal palate morphology
Abnormality of the palate
Abnormality of the roof of the mouth

[ more ]

Agenesis of corpus callosum
Annular pancreas
Aortic valve stenosis
Narrowing of aortic valve
Bipolar affective disorder
Bipolar disorder
Clouding of the lens of the eye
Cloudy lens

[ more ]

Cerebral atrophy
Degeneration of cerebrum
Coarctation of aorta
Narrowing of aorta
Narrowing of the aorta

[ more ]

Death in infancy
Infantile death
Lethal in infancy

[ more ]

Duodenal atresia
Absence or narrowing of first part of small bowel
Ectopic anus


Jacobsen syndrome is caused by a deletion of genetic material at the end of the long (q) arm of chromosome 11. The size of the deletion varies among affected people, but the deleted area almost always includes the tip of chromosome 11. The specific features of Jacobsen syndrome relate to the loss of multiple genes within the deleted region. While the exact function of some of the genes involved is unclear, they appear to be critical for normal development of many parts of the body. In general, larger deletions cause more severe signs and symptoms than smaller deletions.[1]

In about 85% of cases, the deletion is due to a random error during the formation of the egg or sperm, or an error in cell division in early fetal development. This is called a de novo deletion. In about 15% of cases, the deletion is caused by a parent having a balanced translocation or from other, rare types of chromosome rearrangements.[2] Although Jacobsen syndrome is typically not inherited, an affected person can pass the deletion on to his/her children.[1]


Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    There is no cure for Jacobsen syndrome; treatment generally focuses on the specific signs and symptoms present in each individual. Treatment may require the coordinated efforts of a team of various specialists.

    Individuals with low platelet counts (thrombocytopenia) should be monitored regularly. Blood or platelet transfusions may be necessary before or during surgeries. Surgery may be needed to repair various malformations associated with the condition. Complications of certain congenital heart defects (such as rapid heartbeat or fluid accumulation) may be treated with a variety of drugs. Respiratory infections should be treated vigorously and early. Because of the risk of bacterial infection of the heart lining (endocarditis) and valves, those with certain heart defects may need antibiotics before any surgery.

    Eye abnormalities may be treated with surgery, glasses, contact lenses, and/or other measures to improve visual problems. Abnormalities of the joints, tendons, muscles, and bones may be treated by orthopedic techniques, potentially in combination with surgery. Physical therapy may help improve coordination and mobility. Early intervention is important to ensure that affected children reach their full potential.[3]


    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • Unique the Rare Chromosome Disorder Support Group is a source of information and support to families and individuals affected by rare chromosome disorders. Click on the link to view information related to Jacobsen syndrome.
      • MedlinePlus Genetics contains information on Jacobsen syndrome. This website is maintained by the National Library of Medicine.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

        In-Depth Information

        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Jacobsen syndrome. Click on the link to view a sample search on this topic.

          Selected Full-Text Journal Articles

          • The Orphanet Journal of Rare Diseases has published an article with information on this condition. This journal is affiliated with the Orphanet reference portal for information on rare diseases and orphan drugs.


            1. Jacobsen syndrome. Genetics Home Reference (GHR). 2009; https://ghr.nlm.nih.gov/condition/jacobsen-syndrome.
            2. Paul Grossfeld, Teresa Mattine, Concetta Simona Perrotta. Jacobsen syndrome. Orphanet. March, 2009; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=2308.
            3. Chromosome 11, Partial Monosomy 11q. NORD. April 26, 2012; https://rarediseases.org/rare-disease-information/rare-diseases/byID/641/viewAbstract. Accessed 5/30/2012.

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