, Volume 41, Issue 1, pp 457–465 | Cite as

The sex ratio in anencephaly

  • J. Timson


It is shown that the well known excess of females in anencephalic births is statistically significant when compared with (a) the general population and (b) their normal sibs.

There is also a statistically significant difference between the sex ratio of anencephalic births and that of spina bifida births which suggests that there is a definite difference in the genetic component of their aetiology.

These results are discussed with reference to the genetics of anencephaly and spina bifida and a genetic model of the inheritance of the genetic component of anencephaly is given. The significance of a possible cytoplasmic factor is also considered.


General Population Genetic Model Genetic Component Spina Bifida Definite Difference 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Böök J. A. & S. Rayner (1950). A clinical and genetical study of anencephaly.Amer. J. Hum. Genet. 2: 61.Google Scholar
  2. Carter C. O., K. M. Laurence & P. A. David (1967). The genetics of the major central nervous system malformations based on the South Wales sociogenetic investigation.Develop. Med. Child. Neurol. 9: Suppl. 13. 30.Google Scholar
  3. Coffey V. P. & W. J. E. Jessop (1955). Congenital abnormalities.Irish J. Med. Sci. 344: 30.Google Scholar
  4. Collmann R. D. & A. Stoller (1962). Epidemiology of congenital anomalies of the central nervous system with special reference to patterns in the state of Victoria, Australia.J. Ment. Defic. Res. 6: 22.Google Scholar
  5. Frezal J., J. Kelley, M. L. Guillemot & M. Lamy (1964). Anencephaly in France.Amer. J. Hum. Genet. 16: 336.Google Scholar
  6. Macmahon B., T. F. Pugh & T. H. Ingalls (1953). Anencephalus, spina bifida, and hydrocephalus; incidence related to sex, race, season of birth and incidence in siblings.Brit. J. prev. soc. Med. 7: 211.Google Scholar
  7. Nance W. E. (1969). Anencephaly and spina bifida: a possible example of cytoplasmic inheritance in man.Nature 224: 373.Google Scholar
  8. Penrose L. S. (1946). Familial data on 144 cases of anencephaly, spina bifida and congenital hydrocephaly.Ann. Eugenics 13: 73.Google Scholar
  9. Polman A. (1950). Anencephaly, spina bifida, and hydrocephaly.Genetica 25: 29.Google Scholar
  10. Record R. G. & T. McKeown (1949). Congenital malformations of the central nervous system. 1. A survey of 930 cases.Brit. J. prev. soc. Med. 3: 183.Google Scholar
  11. Registrar General (1968). Statistical Review of England and Wales for 1966. Part II. H.M.S.O. London.Google Scholar
  12. Searle A. G. (1959). The incidence of anencephaly in a polytypic population.Ann. Hum. Genet. 23: 279.Google Scholar
  13. Smithells R. W., E. R. Chinn & D. Franklin (1964). Anencephaly in Liverpool.Develop. Med. Child. Neurol. 61: 231.Google Scholar
  14. Stevenson A. G. & H. A. Warnock (1959). Observations on the results of pregnancies of women living in Belfast. 1. Data relating to all pregnancies ending in 1957.Ann. Hum. Genet. 23: 382.Google Scholar
  15. Timson J. (1969). The sex ratio in spina bifida.Genetica. 40: 427.Google Scholar
  16. Williamson E. M. (1965). Incidence and family aggregation of major congenital malformations of the central nervous system.J. Med. Genet. 2: 161.Google Scholar

Copyright information

© Martinus Nijhoff 1970

Authors and Affiliations

  • J. Timson
    • 1
  1. 1.University Department of Medical GeneticsThe Royal InfirmaryManchesterUnited Kingdom

Personalised recommendations