Caudal regression sequence

Other Names: Caudal dysplasia; Sacral agenesis syndrome; Sacral regression syndrome; Sacral agenesis; Sacral defect with anterior meningocele; Caudal regression syndrome

Caudal regression syndrome is a disorder that impairs the development of the lower (caudal) half of the body. It may affect the lower back (including the spinal cord), limbs, genitourinary tract, and the gastrointestinal tract.

Epidemiology

Caudal regression syndrome is estimated to occur in 1 to 2.5 per 100,000 newborns. This condition is much more common in infants born to mothers with diabetes when it affects an estimated 1 in 350 newborns.

Cause

Caudal regression syndrome is a complex condition that may have different causes in different people. The condition is likely caused by the interaction of multiple genetic and environmental factors. One risk factor for the development of caudal regression syndrome is the presence of diabetes in the mother. It is thought that increased blood sugar levels and other metabolic problems related to diabetes may have a harmful effect on a developing fetus, increasing the likelihood of developing caudal regression syndrome. The risks to the fetus are further increased if the mother's diabetes is poorly managed. Caudal regression syndrome also occurs in infants of non-diabetic mothers, so researchers are trying to identify other factors that contribute to the development of this complex disorder.

Some researchers believe that a disruption of fetal development around day 28 of pregnancy causes caudal regression syndrome. The developmental problem is thought to affect the middle layer of embryonic tissue known as the mesoderm. Disruption of normal mesoderm development impairs normal formation of parts of the skeleton, gastrointestinal system, and genitourinary system.

Other researchers think that caudal regression syndrome results from the presence of an abnormal artery in the abdomen, which diverts blood flow away from the lower areas of the developing fetus. Decreased blood flow to these areas is thought to interfere with their development and result in the signs and symptoms of caudal regression syndrome.

Some scientists believe that the abnormal development of the mesoderm causes the reduction of blood flow, while other scientists believe that the reduction in blood flow causes the abnormal mesoderm development. Many scientists think that the cause of caudal regression syndrome is a combination of abnormal mesoderm development and decreased blood flow to the caudal areas of the fetus.

Inheritance

Caudal regression syndrome occurs sporadically, which means it occurs in people with no history of the condition in their family. Multiple genetic and environmental factors likely play a part in determining the risk of developing this condition.

Signs and symptoms

The signs and symptoms of caudal regression syndrome vary depending on the severity of the condition. Affected areas of the body may include the lower back, limbs, the genitourinary tract, and the gastrointestinal tract.

The bones of the lower spine are often abnormally shaped or missing, and the corresponding sections of the spinal cord are also abnormal or missing. Affected people can have scoliosis or other abnormalities of the spine. Spinal abnormalities may affect the chest, which can lead to breathing problems.

Some affected people have small hip bones with a limited range of motion. The buttocks may be flat and dimpled. The leg bones are often underdeveloped. In some people, the legs are bent with the knees pointing outward and the feet tucked underneath the hips. Other features affecting the limbs may include clubfeet, calcaneovalgus, and/or decreased sensation in the lower limbs.

Abnormalities of the genitourinary tract are extremely varied. There may be malformations of the kidneys or absence of a kidney, or kidneys that are fused together (horseshoe kidney). Kidney abnormalities can lead to urinary tract infections and progressive kidney failure. There may also be abnormalities of the bladder, or damage to the nerves that control bladder function. Affected males may have hypospadia (the urethra opening on the underside of the penis) or undescended testes. Affected females may have an abnormal connection between the rectum and vagina. In severe cases, an affected person may have no genitalia (genital agenesis).

Gastrointestinal features may include malrotation of the large intestine, an obstruction of the anal opening, and/or inguinal hernias. Constipation and loss of bladder or bowel control are common.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Abnormal vertebral segmentation and fusion
• Abnormality of the wing of the ilium
• Aplasia/Hypoplasia of the sacrum(Absent/small sacrum)
• Bowel incontinence(Loss of bowel control)
• Decreased muscle mass
• Hypoplastic vertebral bodies(Underdeveloped back bones)
• Impulsivity(Impulsive)
• Maternal diabetes(gestational diabetes)

30%-79% of people have these symptoms

• Abnormality of cardiovascular system morphology
• Anal atresia(Absent anus)
• Ectopic kidney(Abnormal kidney location)
• Joint stiffness(Stiff joint)
• Reduced tendon reflexes
• Renal agenesis(Absent kidney)
• Scoliosis
• Talipes equinovarus(Club feet)
• Ureteral duplication(Double ureter)
• Vesicoureteral reflux

5%-29% of people have these symptoms

• Ambiguous genitalia(Ambiguous external genitalia)
• Arnold-Chiari malformation
• Arrhinencephaly
• Cryptorchidism(Undescended testes)
• Hypertension
• Missing ribs(Absent ribs)
• Oral cleft(Cleft of the mouth)
• Pulmonary hypoplasia(Small lung)
• Renal insufficiency(Renal failure)

Diagnosis

MR-angiography exhibited an anomaly of the unpaired vessels originating from the aorta, a likely relict of a persisting vitelline artery. These findings indicate a potential vascular genesis of CRS, much as in sirenomelia.

Management

Management is supportive and may include surgery. The prognosis is poor; some newborns with severe cases do not survive the neonatal period. Those that survive infancy usually have normal cognitive function.

NIH genetic and rare disease info

• NIH info on Caudal regression sequence

Caudal regression sequence is a rare disease.

Caudal regression sequence Resources
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