What is the prevalence of Sacral agenesis / Caudal regression syndrome?

Sacral agenesis, also known as caudal regression syndrome, is a rare congenital condition with an estimated incidence ranging from 1 in 20,000 to 1 in 50,000 live births. Because the severity of the condition varies significantly—ranging from isolated tailbone abnormalities to complete absence of the sacrum and lumbar spine—it is considered a rare disorder, and true prevalence may be higher due to underdiagnosis of milder cases.

What is the estimated incidence and prevalence of sacral agenesis?

Determining the exact prevalence of sacral agenesis is challenging because it exists on a wide clinical spectrum. According to the NIH Genetic and Rare Diseases Information Center (GARD), the incidence is generally cited as approximately 1 in 25,000 to 1 in 50,000 live births. However, literature reviews suggest that the incidence may be up to 200 times higher in infants born to mothers with pre-existing diabetes mellitus. Because many individuals with mild forms of caudal regression syndrome may remain asymptomatic or undiagnosed for years, these numbers likely underestimate the true population of people living with the condition.

Does sacral agenesis affect males and females differently?

Clinical data suggests a slight male predominance in the diagnosis of sacral agenesis. While the condition affects all ethnic and geographic populations, research indicates that males are diagnosed more frequently than females at a ratio of approximately 3:1. Despite this gender distribution, the condition is not X-linked, and it is considered a sporadic developmental anomaly in the vast majority of cases, rather than an inherited genetic trait.

What are the key factors influencing diagnosis and data accuracy?

The diagnosis of caudal regression syndrome is typically made during the prenatal period via ultrasound or shortly after birth. Several factors complicate the collection of accurate epidemiological data for sacral agenesis:

• Clinical Heterogeneity: The condition ranges from minor sacral hypoplasia to severe sirenomelia (mermaid syndrome), leading to inconsistent reporting.


• Underdiagnosis: Milder cases involving only the distal sacrum may not be identified until adulthood, or potentially never identified at all.


• Maternal Health Association: A significant portion of reported cases are associated with maternal diabetes, which may lead to biased reporting in clinical registries.


• Diagnostic Evolution: Improved high-resolution fetal imaging is leading to earlier identification of sacral agenesis, which may falsely appear as an increase in incidence over time.

How does the DiseaseMaps community reflect these statistics?

While clinical literature provides broad statistical estimates, the DiseaseMaps community offers a vital, real-world perspective on the lived experience of caudal regression syndrome. Currently, 12 individuals have joined the DiseaseMaps community to share their experiences. This small but significant group highlights that while the condition is statistically "rare," the challenges faced by families—ranging from orthopedic management to urological care—are profound and shared across borders, regardless of the specific prevalence numbers.

Next steps

• Consult with a pediatric orthopedic surgeon or a neurosurgeon specializing in spinal dysraphism.


• Discuss genetic counseling with a specialist if you are planning a pregnancy, particularly if there is a history of maternal diabetes.


• Connect with the DiseaseMaps community to share your journey and learn from others who have navigated the diagnostic process for sacral agenesis.


• Request a referral to a multidisciplinary center that manages complex congenital spinal anomalies.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases (GARD) Information Center - Caudal Regression Syndrome.


• Orphanet: Portal for rare diseases and orphan drugs (ORPHA: 79346).


• OMIM (Online Mendelian Inheritance in Man): Entry #605935 (Caudal Regression Syndrome).


• PubMed Central: Clinical review of sacral agenesis and associated maternal risk factors.