Parental consanguinity as a cause for increased incidence of births defects in a study of 238,942 consecutive births.
The risk for birth defects in the offspring of first-cousin matings has been estimated to increase sharply compared to non consanguineous marriages. As a general decline in the frequency of consanguineous marriages was observed in this century, one wonders whether consanguinity is still a factor in the appearance of birth defects in developed countries. Based on our registry of congenital anomalies we tried to answer to this question. In the population studied in North-Eastern France a consanguineous mating was known in 1.21% of the cases with congenital anomalies, vs. 0.27% in controls, (p < 0.001). The frequency of the malformations recorded paralleled the degree of consanguinity: out of 89 malformed children, 51 were seen in first-cousins mating (10.3 times more frequent than in offspring of non consanguineous couples), 17 in second-cousins marriages and 18 in more distant relatives mating. Three were uncle-niece marriage. Excluding known mendelian conditions these numbers were 73, 36, 17 and 17 respectively and the corresponding relative risk were 3.68, 3.01, 3.41 and 4.89 respectively. Therefore there is a negative dose-response effect between level of inbreeding and risk of congenital malformations. Consanguineous mothers were more often pregnant than non consanguineous mothers (p < 0.01) and they had more stillbirths than non consanguineous mothers. These results show that consanguinity is still a factor of birth defects and they must be taken into account for genetic counseling of inbred marriages, in developed countries.
Stoll
C
C
Service de Génétique Médicale, Hôpital de Hautepierre, Strasbourg, France.
Alembik
Y
Y
Roth
M P
MP
Dott
B
B
D000013:Congenital Abnormalities / Q000453:epidemiology / Q000235:genetics*; D003241:Consanguinity; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D010290:Parents; D011247:Pregnancy; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors