Spina Bifida (“Open Back”): Causes

Pathogenesis (development of disease)

During embryonic development, the lower section of the neural tube gives rise to the spinal column (lat.: columna vertebralis) and spinal cord (the upper section of the neural tube develops into the brain and skullcap). Normally, the two arch portions of the vertebrae merge to form a ring. In the vertebral foramen lies the spinal cord ( lat. medulla spinalis or medulla dorsalis), which is surrounded by the spinal meninges (meninx medullae spinalis, meninx spinalis). This process occurs between the third and fourth weeks of pregnancy. If the neural tube in the lower part of the spinal column does not close properly, i.e. the arch closure of one or more vertebrae fails to occur, a cleft develops. This is called “spina bifida” (neural tube defect). Due to the malformation, parts of the spinal cord as well as nerves can protrude through the gap in the shape of a sac. The so-called zele (meningocele; myelomeningocele) develops.

Spina bifida develops between the 19th and 28th day of embryonic development. During this period, called “primary neurulation,” the neural tube is formed from the neural plate and closed.

It is believed that primary inhibition of the closing process of the posterior vertebral arches (arcus vertebrae, synonym: neural arch) causes the vertebral fissure. Animal studies indicate that certain pattern control genes (e.g. Hox-1,6 gene) are not expressed as required.

Vitamin folic acid, which is involved in neurulation, makes a crucial contribution to adequate closure of the neural tube.

Etiology (Causes)

The etiology of spina bifida is not yet well understood.

Biographic causes

  • Sporadic, rarely familial occurrence.
  • Genetic burden
    • Genetic risk depending on gene polymorphisms:
      • Genes/SNPs (single nucleotide polymorphism):
        • Genes: MTHFD1_Arg653Gln (MTHFD1), MTHFR _C677T (MTHFR).
        • SNP: rs2236225 in the MTHFD1_Arg653Gln gene.
          • Allele constellation: CT (1.5-fold if the allele constellation is present in the mother)
          • Allele constellation: TT (1.5-fold, if the allele constellation is present in the mother).
        • SNP: rs1801133 in the gene MTHFR _C677T
          • Allele constellation: CT (higher risk if the allele constellation is present in the mother).
          • Allele constellation: CC (lower risk if the allele constellation is present in the mother).
          • Allele constellation: TT (lower risk if the allele constellation is present in the mother).

Behavioral causes

  • Nutrition
    • Folic acid deficiency

Causes related to disease

Medication