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PubMed This is a summary of 22 peer-reviewed journal articles Updated
Hematology

How Jacobsen Syndrome Affects the Body: Heart, Blood, Immune, and More

At a Glance

Jacobsen syndrome is a genetic condition that affects multiple body systems. Common challenges include a bleeding disorder called Paris-Trousseau syndrome, frequent infections, heart defects, and skull shape changes. Due to bleeding risks, children should avoid NSAIDs like ibuprofen without medical clearance.

Jacobsen syndrome is a multisystem condition, meaning it can affect several different parts of the body at the same time. Because it is a contiguous gene deletion syndrome, the symptoms are caused by the loss of several different genes that sit next to each other on chromosome 11 [1]. While every child is different, most will face challenges involving their blood, immune system, heart, and the shape of their skull.

Blood: Paris-Trousseau Syndrome

Over 90% of individuals with Jacobsen syndrome have a specific bleeding disorder called Paris-Trousseau syndrome (PTS) [2]. This condition is caused by the loss of the FLI1 gene, which is essential for making platelets—the cells that help your blood clot [3][4].

  • Thrombocytopenia: Most newborns with PTS have a low platelet count (thrombocytopenia) at birth [3]. While the count often improves as the child grows, it rarely reaches a completely normal level [2].
  • Platelet Dysfunction: Even if the number of platelets increases, the platelets themselves do not work correctly because they lack certain “storage units” called alpha-granules [3][5].

CRITICAL SAFETY WARNING: Medications and Bleeding
Because of this platelet dysfunction, never give your child NSAIDs (like ibuprofen, Motrin, Advil) or aspirin unless explicitly cleared by your hematologist. These medications further interfere with how platelets work and can precipitate dangerous bleeding [6][3]. Always consult your doctor about using acetaminophen (Tylenol) instead for standard fevers or pain.

  • Everyday Bumps and Bruises: Your child will likely bruise easily. Since toddlers with motor delays are prone to falls, it’s vital to have a plan. While small bruises on the shins are typical, any head trauma or bump to the head warrants an immediate ER visit or consultation with your medical team to rule out internal bleeding [6][7].

Immune System: Fighting Infections

Because the blood and immune systems are closely linked, Jacobsen syndrome is also recognized as a type of primary immunodeficiency [8]. This means the body’s natural defense system is weakened.

  • T-cell and B-cell Issues: Children often have lower numbers of T-lymphocytes and B-lymphocytes, the “soldier cells” of the immune system [9][10].
  • Frequent Infections: This can lead to recurrent ear infections, sinus infections, and pneumonia [11][10].
  • Everyday Impact: Ask your immunologist for practical guidance on everyday life. You may need to discuss whether daycares are safe, and what special considerations are needed regarding standard childhood live vaccines given the immunodeficiency [7][9]. Some children may need intravenous immunoglobulin (IVIG) therapy [12].

Heart: Structural Defects

Heart issues are common and are often driven by the loss of the ETS1 gene [13][14]. This gene helps guide cells as the heart is forming in the womb [15]. Common heart defects include:

  • Hypoplastic Left Heart Syndrome (HLHS): A serious condition where the left side of the heart is severely underdeveloped [16][13].
  • Shone’s Complex: A group of defects that obstruct blood flow on the left side of the heart [16].
  • Double Outlet Right Ventricle (DORV): A condition where the two main arteries of the heart both come out of the right ventricle [16][15].
    Many of these defects require surgical repair, and early evaluation by a pediatric cardiologist is vital [17][18].

Kidneys: Structural Defects

The same genetic factors (such as the ETS1 gene) that affect the heart can also impact kidney development [19].

  • Some children are born with missing kidneys, abnormally formed kidneys, or duplicated ureters (the tubes carrying urine) [19][16].
  • Because these anomalies can be entirely symptomless at first, a baseline renal ultrasound is a critical part of the initial checkup [19].

Gastrointestinal Issues

Feeding difficulties and severe, chronic constipation are hallmarks of the syndrome that heavily impact a child’s daily quality of life [17][20].

  • Constipation and Reflux: These GI challenges often require aggressive medical management, dietary interventions, and sometimes collaboration with a pediatric gastroenterologist to keep the child comfortable and growing [20].

Skull and Face: Trigonocephaly

Many children with Jacobsen syndrome have a distinct forehead shape called trigonocephaly, which gives the forehead a pointed or triangular appearance [2]. This is often caused by craniosynostosis, where the sutures (growth seams) in the front of the skull fuse together too early [21].
If the skull fuses too early, it can limit the space the brain has to grow. A neurosurgeon may recommend a procedure to reshape the skull and ensure there is enough room for healthy brain development [21][22].

Common questions in this guide

Why do children with Jacobsen syndrome bruise easily?
Most children with Jacobsen syndrome have a bleeding disorder called Paris-Trousseau syndrome, which is caused by a missing gene. This condition lowers platelet counts and prevents platelets from working correctly to clot blood. As a result, children often bruise easily and are at a higher risk for bleeding.
Can I give my child with Jacobsen syndrome ibuprofen for a fever?
You should never give your child NSAIDs like ibuprofen, Motrin, or aspirin without explicit clearance from your hematologist. These medications interfere with how blood platelets work and can cause dangerous bleeding. Always consult your doctor about using safer alternatives like acetaminophen instead.
What heart defects are associated with Jacobsen syndrome?
Children with Jacobsen syndrome often have structural heart defects due to the loss of a specific gene that guides heart development in the womb. Common conditions include Hypoplastic Left Heart Syndrome and Double Outlet Right Ventricle. Many of these defects affect blood flow and may require early surgical repair.
What does trigonocephaly mean for my child?
Trigonocephaly is a condition where the forehead has a pointed or triangular appearance. In Jacobsen syndrome, this is often caused by craniosynostosis, which happens when the skull bones fuse together too early. A neurosurgeon may recommend a procedure to reshape the skull to ensure the brain has enough room to grow.
Does Jacobsen syndrome affect the immune system?
Yes, Jacobsen syndrome is considered a type of primary immunodeficiency. Children often have lower numbers of T-cells and B-cells, which are vital cells for fighting off illness. This weakened immune system can lead to recurrent ear infections, sinus infections, and pneumonia.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Has my child been formally evaluated for Paris-Trousseau syndrome, including a platelet function test?
  2. 2.What specific heart and kidney defects were identified on the ultrasound, and are they related to the ETS1 gene deletion?
  3. 3.Can you explain the results of my child's immunology workup, specifically the T-cell and B-cell counts?
  4. 4.Does my child have craniosynostosis, and do we need to consult a neurosurgeon regarding their trigonocephaly?
  5. 5.What is our specific plan for safely managing my child's fevers, pain, and vaccinations given their bleeding and immune risks?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (22)
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    Jacobsen syndrome: Advances in our knowledge of phenotype and genotype.

    Favier R, Akshoomoff N, Mattson S, Grossfeld P

    American journal of medical genetics. Part C, Seminars in medical genetics 2015; (169(3)):239-50 doi:10.1002/ajmg.c.31448.

    PMID: 26285164
  2. 2

    A Case Report: Jacobsen Syndrome Complicated by Paris-Trousseau Syndrome and Shone's Complex.

    Malia LA, Wolkoff LI, Mnayer L, et al.

    Journal of pediatric hematology/oncology 2015; (37(7)):e429-32 doi:10.1097/MPH.0000000000000372.

    PMID: 26056793
  3. 3

    Recurrent Spontaneous Intracranial Hemorrhage in a Patient With Jacobsen Syndrome.

    Suryadevara N, Ahmed R, El-Dokla A

    Neurology. Clinical practice 2021; (11(4)):e598-e599 doi:10.1212/CPJ.0000000000000963.

    PMID: 34484972
  4. 4

    Singling out FLI1 in Paris-Trousseau syndrome.

    Falet H

    Blood 2017; (129(26)):3399-3401 doi:10.1182/blood-2017-05-781252.

    PMID: 28663223
  5. 5

    Mice Haploinsufficient for Ets1 and Fli1 Display Middle Ear Abnormalities and Model Aspects of Jacobsen Syndrome.

    Carpinelli MR, Kruse EA, Arhatari BD, et al.

    The American journal of pathology 2015; (185(7)):1867-76.

    PMID: 26093983
  6. 6

    Jacobsen Syndrome, Paris-Trousseau Syndrome, and Dental Extractions: Case Report, Medical, Dental, and Social Considerations.

    Vo D, Co-Vu J, Wynn T, Langford DK

    Special care in dentistry : official publication of the American Association of Hospital Dentists, the Academy of Dentistry for the Handicapped, and the American Society for Geriatric Dentistry 2025; (45(4)):e70086 doi:10.1111/scd.70086.

    PMID: 40842178
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    Jacobsen syndrome and neonatal bleeding: report on two unrelated patients.

    Serra G, Memo L, Antona V, et al.

    Italian journal of pediatrics 2021; (47(1)):147 doi:10.1186/s13052-021-01108-2.

    PMID: 34210338
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    The 11q Terminal Deletion Disorder Jacobsen Syndrome is a Syndromic Primary Immunodeficiency.

    Dalm VA, Driessen GJ, Barendregt BH, et al.

    Journal of clinical immunology 2015; (35(8)):761-8 doi:10.1007/s10875-015-0211-z.

    PMID: 26566921
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    11q terminal deletion and combined immunodeficiency (Jacobsen syndrome): Case report and literature review on immunodeficiency in Jacobsen syndrome.

    Blazina Š, Ihan A, Lovrečić L, Hovnik T

    American journal of medical genetics. Part A 2016; (170(12)):3237-3240 doi:10.1002/ajmg.a.37859.

    PMID: 27605496
  10. 10

    Immunological Evaluation of Patients Affected with Jacobsen Syndrome Reveals Profound Not Age-Related Lymphocyte Alterations.

    Baronio M, Saettini F, Gazzurelli L, et al.

    Journal of clinical immunology 2022; (42(2)):365-374 doi:10.1007/s10875-021-01169-2.

    PMID: 34802108
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    Patients with Chromosome 11q Deletions Are Characterized by Inborn Errors of Immunity Involving both B and T Lymphocytes.

    Huisman EJ, Brooimans AR, Mayer S, et al.

    Journal of clinical immunology 2022; (42(7)):1521-1534 doi:10.1007/s10875-022-01303-8.

    PMID: 35763218
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    Recurrent pneumonia in a child with Jacobsen syndrome and common variable immune deficiency.

    Thomas RG

    Clinical case reports 2023; (11(6)):e7472 doi:10.1002/ccr3.7472.

    PMID: 37323257
  13. 13

    ETS1 and HLHS: Implications for the Role of the Endocardium.

    Grossfeld P

    Journal of cardiovascular development and disease 2022; (9(7)) doi:10.3390/jcdd9070219.

    PMID: 35877581
  14. 14

    11q24.2q24.3 microdeletion in two families presenting features of Jacobsen syndrome, without intellectual disability: Role of FLI1, ETS1, and SENCR long noncoding RNA.

    Conrad S, Demurger F, Moradkhani K, et al.

    American journal of medical genetics. Part A 2019; (179(6)):993-1000 doi:10.1002/ajmg.a.61113.

    PMID: 30888095
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    ETS1 loss in mice impairs cardiac outflow tract septation via a cell migration defect autonomous to the neural crest.

    Lin L, Pinto A, Wang L, et al.

    Human molecular genetics 2022; (31(24)):4217-4227 doi:10.1093/hmg/ddac174.

    PMID: 35899771
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    Partial Jacobsen syndrome phenotype in a patient with a de novo frameshift mutation in the ETS1 transcription factor.

    Tootleman E, Malamut B, Akshoomoff N, et al.

    Cold Spring Harbor molecular case studies 2019; (5(3)) doi:10.1101/mcs.a004010.

    PMID: 31160359
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    Jacobsen syndrome associated with Shone's complex: a case report.

    Brum A, Laskoski LV, Matos FGOA, d'Arce LPG

    Revista paulista de pediatria : orgao oficial da Sociedade de Pediatria de Sao Paulo 2025; (43()):e2024136 doi:10.1590/1984-0462/2025/43/2024136.

    PMID: 39841699
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    Jacobsen Syndrome with Hypoplastic Left Heart Syndrome: Outcome after Cardiac Transplantation.

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    Journal of cardiovascular development and disease 2022; (10(1)) doi:10.3390/jcdd10010008.

    PMID: 36661903
  19. 19

    Gene-targeted deletion in mice of the Ets-1 transcription factor, a candidate gene in the Jacobsen syndrome kidney "critical region," causes abnormal kidney development.

    Ye M, Xu L, Fu M, et al.

    American journal of medical genetics. Part A 2019; (179(1)):71-77 doi:10.1002/ajmg.a.40481.

    PMID: 30422383
  20. 20

    Scurvy Findings in a Child with Jacobsen Syndrome: A Case Report.

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    JBJS case connector 2019; (9(3)):e0352 doi:10.2106/JBJS.CC.18.00352.

    PMID: 31584905
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    Trigonocephaly: Quantitative Comparison of the Complete Vault Reconstruction and Minimally Invasive Suturectomy.

    Masoudi MS, Yousefi S, Yousefi O, et al.

    World neurosurgery 2022; (166()):e77-e83 doi:10.1016/j.wneu.2022.06.093.

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    Quantitative outcomes of endoscopic strip craniectomy for metopic craniosynostosis in children with severe trigonocephaly.

    Lajthia O, Rogers GF, Tsering D, et al.

    Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery 2021; (37(2)):573-579 doi:10.1007/s00381-020-04849-3.

    PMID: 32812117

This page provides educational information about the symptoms and multisystem effects of Jacobsen syndrome. It is not a substitute for professional medical advice; always consult your child's care team before using medications like NSAIDs.

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