Spina bifida (SB) is a neural tube defect (NTD) caused by the failure of the fetus's spine to close properly during the first month of pregnancy.

The most common types of SB are:

 spina bifida aperta
 myelomeningocele (the spinal cord and the meninges protrude from an opening in the spine)
 meningocele (the spinal cord develops normally but the meninges protrude from a spinal opening)
 spina bifida occulta (one or more vertebrae are malformed and covered by a layer of skin)
 spina bifida cystica

Localization

 cervical spina bifida
 thoracic spina bifida
 lombar spina bifida
 sacral spina bifida

Suceptibility

 variation in genes that are involved in the folate-homocysteine metabolic pathway

• variants in gene coding for methylenetetrahydrofolate reductase (MTHFR)
• variants in gene coding for the trifunctional enzyme methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase (MTHFD1) (#12384833#)
• variants in genes involved in homocysteine remethylation/methionine biosynthesis
  • methionine synthase (MTR)
  • methionine synthase reductase (MTRR)

 Loci

• 1q43
• 5p15.3-p15.2

 X-linked spina bifida (MIM.300293)

• lumbosacral spina bifida and myeloschisis
• de novo/autosomal translocation, t(X;22)(q27;q12.1)

Associations

 encephalocele (#9182784#)
 anencephaly (anencephaly-spina bifida association)

• X-linked anencephaly-spina bifida association (MIM.301410)

 sacral agenesis
 neural crest anomalies (8.5%) (#10508971#)

• auditory
• pigmentary disorders
• familial neural crest anomalies (3.9%)
  • Waardenburg syndrome (1.7%) (PAX3 mutations) (#8209923#, #8465867#)

 association split hand-onbstructive uropathy- spina bifida and diaphragmatic defects (MIM.183802) (#3308683#)

 abdominal wall defects

• gastroschisis
  • spina bifida-gastroschisis association (hp7883)

• omphalocele
  • association gonadal agenesis, encephalocele, spina bifida, omphalocele (GAESBO) (#9182784#)

 hypospadias (#7977461#)
 multiple pilomatricomas (#15804314#)

See also

 spinal malformations
 neural tube defects
 myelomeningocele