Risks of selected congenital malformations among offspring of mixed race-ethnicity.
BACKGROUND
Little is known about the occurrence of specific congenital malformations among offspring of mixed race-ethnicity.


METHODS
Using data from a population-based registry, we explored the occurrence of selected malformation phenotypes in offspring to parents who were of different race-ethnicity. Data were derived from the California Birth Defects Monitoring Program, a population-based active surveillance system for collecting information on infants and fetuses with congenital malformations using multiple source ascertainment. Approximately 2.6 million live births and stillbirths occurred during 1989-2000. Information on parental race-ethnicity (non-Hispanic white, Hispanic, black, and Asian) was obtained from birth certificates and fetal death files. Malformation phenotypes studied were spina bifida, anencephaly, cleft lip, cleft palate, tetralogy of Fallot, d-transposition of great arteries, hypospadias, small intestinal atresia, preaxial polydactyly, microtia, and hypertrophic pyloric stenosis.


RESULTS
A total of 11.2% of births were to parents of mixed race-ethnicity. Compared to births of parents who were both white, moderately increased risks (risk ratio >/= 1.7) of anencephaly, polydactyly, and microtia, and decreased risks (risk ratio </= 0.6) of hypospadias and hypertrophic pyloric stenosis were observed among births of several mixed race-ethnicity groups. For anencephaly, polydactyly, and microtia, but not other phenotypes, the risks were different depending on whether maternal versus paternal race-ethnicity was considered. Risks observed between births of a nonwhite parent and a white parent and births of parents who were both nonwhite were similar for most malformation phenotypes.


CONCLUSIONS
Some malformation phenotypes appear to vary in their risk based on mixed racial-ethnic groupings.
Yang
Juan
J
March of Dimes Birth Defects Foundation, California Birth Defect Monitoring Program, Berkeley, CA 94710, USA. jya@cbdmp.org
Carmichael
Suzan L
SL
Kaidarova
Zhanna
Z
Shaw
Gary M
GM
D002140:California / Q000453:epidemiology; D000013:Congenital Abnormalities / Q000453:epidemiology / Q000208:ethnology*; D005006:Ethnicity; D006801:Humans; D010641:Phenotype; D044469:Racial Groups; D012042:Registries; D012307:Risk Factors