rss
J Med Genet 1993;30:849-851 doi:10.1136/jmg.30.10.849
  • Research Article

Upper and lower neural tube defects: an alternate hypothesis.

  1. B H Garabedian,
  2. F C Fraser
  1. Centre for Human Genetics, McGill University, Montreal, Quebec, Canada.

      Abstract

      It has been suggested that neural tube defects (NTDs) of the upper type (anencephaly, encephalocele, and thoracic spina bifida) may have a pathogenesis different from those of the lower type (lumbosacral spina bifida), since recurrent cases within a sibship were said always to be concordant with respect to NTD type. Also, spontaneous abortion, additional malformation, and recurrence rate were observed to be higher in the upper group, and there was an excess of females in upper NTD probands. To test this hypothesis, we measured the above variables in upper and lower NTDs in a sample from Quebec. We found less than full concordance (50%) of NTD type in 18 sib pairs. Recurrence rate was not significantly lower in the lower NTD group (5.6 v 5.8%). The other variables were in general agreement with previous studies, inconsistent findings possibly attributable to different NTD population incidences. These findings can be accounted for if upper and lower NTDs share a similar pathogenesis and the embryo is more susceptible during early than late neural tube formation.

      This Article

      1. Abstract
      2. PDF

      Responses

      1. Submit a response
      2. No responses published

      Register for free content

      The full back archive is now available for all BMJ Journals. Institutional subscribers may access the entire archive as part of their subscription. Personal subscribers will also have access to all content when logged in. Non-subscribers who register have free access to all articles published before 2006 right back to volume 1 issue 1. Register here to access the free archive of all BMJ Journals.

      Don't forget to sign up for content alerts so you keep up to date with all the articles as they are published.