Malformations in different ethnic groups.

AnnotationsMalformations in different ethnic groups Depressingly little is known about the cause of malformations.Despite a history dating back to antiquity and an incidence approaching one in 30, over 50% ofmajor congenital malformations, defined as those that seriously interfere with viability or physical well being, are unexplained.Thus any approach that may shed light on an area of such shameful medical ignorance is to be welcomed.The study of ethnic differences is one such approach. Pitfalls and limitationsIt is worth considering in some detail the problems confronting the epidemiologist wishing to explore this area, for they are formidable.