Caudal regression syndrome
Rare congenital disorder of lower spine development.
Caudal regression syndrome, also called sacral agenesis or underdevelopment of the sacrum, is a rare birth condition where the lower part of the spine doesn't form normally. It happens in about one out of every 60,000 births. The severity varies widely: some babies have only minor spinal differences, while others are missing lower vertebrae, parts of the pelvis, or sections of the thoracic or lumbar spine. Most people with the condition grow up to be otherwise healthy adults, though they often have trouble walking and experience incontinence.
The condition develops from something that goes wrong between the third and seventh week of pregnancy. Normally, the lower spine and its nerves begin forming around the fourth week, but the sacrum and lower spine continue developing into the sixth to eighth week. In caudal regression syndrome, the migration of mesoderm cells during early development is disrupted, leading to a range of outcomes—from small lesions on the lower vertebrae to complete fusion of the legs. The exact cause isn't known, but it's thought to involve both genetic and environmental factors, and different types may have different triggers. One well-known type, sacral agenesis syndrome (which involves missing lumbar, sacral, and coccyx bones along with underdeveloped legs), is strongly linked to maternal diabetes. While the overall rate of caudal regression syndrome is very low (1 in 60,000), it jumps to about 1 in 350 births among mothers with diabetes. A hereditary form called Currarino syndrome is often caused by a mutation in the Hb9 (or HlxB9) gene. The condition was once thought to be related to sirenomelia ("Mermaid syndrome"), but it's now known they are not connected.
Malformations are grouped into four levels. The mildest involves partial, one-sided sacral deformation. The second level is a uniform, two-sided deformation. The most severe types involve a total lack of the sacrum. Depending on the level, bowel or bladder problems may occur. If the anus is not formed, a permanent colostomy might be needed. Incontinence may require self-catheterization or other continence management. The condition often affects the knees, legs, or feet, sometimes requiring surgery. For those with tightly webbed, bent knees or fused straight knees, disarticulation at the knee can improve mobility and seating.
- Field
- Congenital disorder
- Known for
- Abnormal development of the lower spine, associated with maternal diabetes and genetic mutations
- Incidence
- Approximately 1 per 60,000 live births
- Types
- Four levels of malformation, from partial unilateral sacral deformation to total absence of the sacrum
Lore & Background
The condition arises from some factor or set of factors present during approximately the 3rd to 7th week of fetal development. Formation of the sacrum and lower back and corresponding nervous system begins around the 4th week, but continues developing into the 6th to 8th week. Due to abnormal gastrulation, mesoderm migration is disturbed, resulting in symptoms varying from minor lesions of the lower vertebrae to complete fusion of the lower limbs. While the exact cause is unknown, it has been speculated that the condition has a combination of environmental and genetic causes, and that various types may have differing causes.
Reader's Guide
Caudal regression syndrome is significant as a rare congenital disorder that illustrates the complex interplay of genetic and environmental factors in fetal development. Its association with maternal diabetes provides a clear example of how maternal health conditions can influence congenital anomalies. The condition's spectrum of severity, from minor spinal abnormalities to complete absence of the sacrum and lower limb fusion, demonstrates the variability in developmental disruptions. Prognosis and treatment depend on the type of malformation, with options ranging from prosthetic legs and wheelchair mobility to disarticulation surgery at the knee. Notably, there is typically no cognitive impairment associated with this disability, and many individuals live independently, attend college, and have careers. Notable individuals such as Spencer West, who climbed Mount Kilimanjaro using only his hands, and Zion Clark, who broke the Guinness World Record for 20 m running on hands, highlight the achievements possible despite the condition. The condition's legacy includes raising awareness about congenital disorders and the importance of adaptive technologies and inclusive opportunities.
Did You Know?
- Caudal regression syndrome occurs at a rate of approximately one per 60,000 live births.
- The condition has a greatly increased incidence among infants born to mothers with diabetes, estimated at 1 in 350 newborns of mothers with diabetes.
- The dominant inherited sacral agenesis (Currarino syndrome) is very often correlated with a mutation in the Hb9 (also called HlxB9) gene.
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