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PubMed This is a summary of 13 peer-reviewed journal articles Updated
Pediatrics

The Biology and Genetics of Prune Belly Syndrome

At a Glance

Prune Belly Syndrome (PBS) is a rare developmental condition primarily affecting males. It is believed to result from either early embryo cell disruption or a fetal urinary tract blockage. While mostly random, rare genetic mutations like FLNA and PIEZO1 can play a role in its development.

While the outward signs of Prune Belly Syndrome (PBS) are visible at birth, the biological processes that cause them begin very early in pregnancy. Understanding the “how” and “why” behind the condition can help you navigate the diagnostic process and differentiate PBS from other similar-looking conditions.

Biological Mechanisms: Two Leading Theories

Scientists are still debating exactly how PBS develops. There are two primary schools of thought regarding the pathogenesis (the biological mechanism by which a disease develops):

  • Mesodermal Arrest Theory: This theory suggests that between the 6th and 10th weeks of pregnancy, there is an “insult” or error in the development of the mesoderm. The mesoderm is a middle layer of embryo cells that is responsible for forming the abdominal muscles, the urinary tract, and the reproductive organs. If these cells stop developing (arrest) correctly, all three parts of the PBS triad are affected simultaneously. [1][2]
  • Urinary Obstruction Theory: This theory proposes that the abdominal wall issues are a secondary effect. It suggests that a severe, early blockage (obstruction) in the fetal urinary tract causes the bladder and ureters to swell significantly. This massive swelling stretches the abdominal wall so much that the muscles eventually wither away (atrophy), leaving the skin wrinkled. [3][4]

The Role of Genetics and Gender

PBS affects males in approximately 95% of cases. [5] The biological reason for this gender split is largely thought to be anatomical: the male urethra develops in a much more complex way than the female urethra, making it significantly more prone to the early blockages described in the obstruction theory. [3]

While most cases of PBS occur sporadically (without a family history), recent research has identified specific genetic markers that may play a role in a small subset of cases:

  • FLNA (Filamin A): Mutations in the FLNA gene (located on the X chromosome) have been found in a tiny fraction of patients. This gene helps cells structure themselves during muscle and urinary tract development. [6][7]
  • PIEZO1: This gene helps cells sense physical pressure. Loss-of-function variants (mutations that stop the gene from working) in PIEZO1 have been found in some children, potentially affecting how the urinary tract responds to fluid pressure. [8]
  • Copy Number Variants (CNVs): These are instances where sections of DNA are either missing (deletions) or extra (duplications). For example, a 17q12 deletion is a specific genetic change linked to kidney and urinary tract abnormalities. [2][9]

Differentiating PBS from “Look-Alikes”

Because the symptoms of PBS overlap with other conditions, doctors use imaging and physical exams to confirm the diagnosis.

Condition Key Differences from PBS
Posterior Urethral Valves (PUV) This is a physical blockage in the male urethra. While it causes urinary dilation, it typically does not involve the abdominal wall muscle deficiency seen in PBS. [3]
MMIHS Megacystis Microcolon Intestinal Hypoperistalsis Syndrome involves a massive bladder (megacystis) but also includes a very small colon and a digestive tract that doesn’t move food properly. [10]
Pseudo-Prune Belly This term is used when a child has the urinary tract features of PBS but may only have partial abdominal muscle issues or lacks the testicular component (which is how PBS presents in females). [11]

Confirming the Diagnosis

To confirm PBS and rule out look-alikes, doctors typically use:

  1. Physical Exam: To check for the wrinkled abdominal skin and feel for undescended testes. [12]
  2. Renal Ultrasound: To visualize the degree of dilation (stretching) in the kidneys and ureters. [7]
  3. VCUG (Voiding Cystourethrogram): A specialized X-ray that shows how the bladder empties and whether urine is flowing backward toward the kidneys (reflux). [13]

Common questions in this guide

What causes Prune Belly Syndrome?
The exact cause is still debated, but there are two main theories. It may happen due to a disruption in the middle layer of embryo cells during early pregnancy, or from a severe early blockage in the fetal urinary tract that stretches the abdominal wall.
Why does Prune Belly Syndrome mostly affect males?
PBS affects males in about 95% of cases. This is likely because the male urethra develops in a much more complex way than the female urethra, making it significantly more prone to early blockages during fetal development.
Is Prune Belly Syndrome genetic?
Most cases happen sporadically without a known family history. However, recent research has found that mutations in certain genes, such as FLNA or PIEZO1, can play a role in a small number of children.
How is Prune Belly Syndrome diagnosed?
Doctors confirm PBS through a physical exam to check for wrinkled abdominal skin and undescended testicles. They also use imaging tests like a renal ultrasound and a voiding cystourethrogram (VCUG) to evaluate the urinary tract.
How is Prune Belly Syndrome different from Posterior Urethral Valves?
While both conditions involve blockages in the urinary tract, Posterior Urethral Valves (PUV) typically do not cause the severe abdominal muscle deficiency that is a hallmark sign of Prune Belly Syndrome.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does my child’s presentation align more closely with the 'mesodermal arrest' or 'obstruction' theory of development?
  2. 2.Have you recommended any genetic testing, such as a chromosomal microarray, for our child?
  3. 3.How did the medical team definitively rule out Posterior Urethral Valves (PUV) as the primary cause of the urinary dilation?
  4. 4.Are there any signs of intestinal issues that would point toward a look-alike condition like MMIHS?

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 (13)
  1. 1

    Unusual variant of pseudo prune belly syndrome.

    Loganathan AK, Barla S S RK, Kurian JJ

    BMJ case reports 2020; (13(10)) doi:10.1136/bcr-2020-236611.

    PMID: 33127698
  2. 2

    Rare copy number variants identified in prune belly syndrome.

    Boghossian NS, Sicko RJ, Giannakou A, et al.

    European journal of medical genetics 2018; (61(3)):145-151 doi:10.1016/j.ejmg.2017.11.008.

    PMID: 29174092
  3. 3

    Further evidence of the etiology of prune belly syndrome provided by a transient massive intraabdominal cyst in a female.

    Wijesinghe US, Muthucumaru M, Beasley SW

    Journal of pediatric surgery 2016; (51(8)):1390-3.

    PMID: 27287284
  4. 4

    Prune Belly Syndrome Associated with Interstitial 17q12 Microdeletion.

    Puvabanditsin S, Shim M, Suell J, et al.

    Case reports in urology 2022; (2022()):7364286 doi:10.1155/2022/7364286.

    PMID: 35198258
  5. 5

    Prune belly syndrome in Finland - A population-based study on current epidemiology and hospital admissions.

    Pakkasjärvi N, Syvänen J, Tauriainen A, et al.

    Journal of pediatric urology 2021; (17(5)):702.e1-702.e6 doi:10.1016/j.jpurol.2021.06.019.

    PMID: 34261584
  6. 6

    Prune belly syndrome in surviving males can be caused by Hemizygous missense mutations in the X-linked Filamin A gene.

    Iqbal NS, Jascur TA, Harrison SM, et al.

    BMC medical genetics 2020; (21(1)):38 doi:10.1186/s12881-020-0973-x.

    PMID: 32085749
  7. 7

    Modern management of and update on prune belly syndrome.

    Lopes RI, Baker LA, Dénes FT

    Journal of pediatric urology 2021; (17(4)):548-554 doi:10.1016/j.jpurol.2021.04.010.

    PMID: 34016542
  8. 8

    PIEZO1 loss-of-function compound heterozygous mutations in the rare congenital human disorder Prune Belly Syndrome.

    Amado NG, Nosyreva ED, Thompson D, et al.

    Nature communications 2024; (15(1)):339 doi:10.1038/s41467-023-44594-0.

    PMID: 38184690
  9. 9

    Case Report: Novel Copy Number Variant 16p11.2 Duplication Associated With Prune Belly Syndrome.

    Talluri S, Goedde MA, Rosenberg E, et al.

    Frontiers in pediatrics 2021; (9()):729932 doi:10.3389/fped.2021.729932.

    PMID: 34631626
  10. 10

    Megacystis-microcolon-intestinal hypoperistalsis syndrome associated with prune belly syndrome: a case report.

    Akhtar T, Alladi A, Siddappa OS

    Journal of neonatal surgery 2012; (1(2)):26.

    PMID: 26023385
  11. 11

    Pseudo Prune Belly Syndrome: Diagnosis Revealed by Imaging - A Case Report and Brief Review.

    Grover H, Sethi S, Garg J, Ahluwalia AP

    Polish journal of radiology 2017; (82()):252-257 doi:10.12659/PJR.899743.

    PMID: 28580040
  12. 12

    Prune belly syndrome: current perspectives.

    Arlen AM, Nawaf C, Kirsch AJ

    Pediatric health, medicine and therapeutics 2019; (10()):75-81 doi:10.2147/PHMT.S188014.

    PMID: 31496864
  13. 13

    Long term follow-up in a patient with prune-belly syndrome - a care compliant case report.

    Cornel A, Duicu C, Delean D, et al.

    Medicine 2019; (98(33)):e16745 doi:10.1097/MD.0000000000016745.

    PMID: 31415370

This page explains the biological and genetic factors of Prune Belly Syndrome for educational purposes. It does not replace professional medical advice from your pediatric urologist or medical geneticist.

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