Racial and ethnic variations in the prevalence of orofacial clefts in California, 1983-1992

TLDR

Prevalence differences in orofacial clefts may stem from environmental and genetic factors. The study examined how parental race, ethnicity, and maternal birthplace influence the prevalence of oral cleft anomalies in California births from 1983 to 1992. Cleft cases were identified through the California Birth Defects Monitoring Program, a population‑based registry, among 2,221,755 births and fetal deaths. African Americans had lower rates of both CL+/-P and CP, Native Americans higher CL+/-P, and foreign‑born Chinese and Filipinos showed modestly lower and higher risks, respectively, though confidence intervals were wide.

Abstract

To investigate variations in the prevalence of oral cleft anomalies according to parental race and ethnicity and maternal country of birth, the authors analyzed a cohort of 2,221,755 live births and fetal deaths delivered between 1983 and 1992 to residents of California. A total of 2,329 cleft lip with or without cleft palate (CL +/- P) cases and 1,475 cleft palate alone (CP) cases were identified by the California Birth Defects Monitoring Program, a population-based registry. Compared to Whites, the prevalence of CL +/- P was lower among African Americans (prevalence ratio (PR) = 0.56, 95% confidence interval (CI) = 0.45-0.69), higher among Native Americans (PR = 1.81, CI = 1.20-2.69), and the same among the Japanese (PR = 1.07, CI = 0.62-1.82) and Chinese (PR = 0.96, CI = 0.71-1.29). The risk of CL +/- P was slightly lower among the offspring of foreign-born Chinese women relative to U.S.-born Chinese women (PR = 0.71, CI = 0.33-1.57), and slightly higher among foreign-born Filipinos relative to their U.S.-born counterparts (PR = 1.37, CI = 0.57-3.53), although confidence intervals around these risk estimates were wide owing to sparse data. For CP, lower prevalences were observed among African Americans (PR = 0.72, CI = 0.58-0.91) and Hispanics (PR = 0.77, CI = 0.67-0.87) than among Whites. The risk of CP was higher among foreign-born Filipinos compared to U.S.-born Filipinos (PR = 1.52, CI = 0.58-4.33), although the confidence interval around this estimate included unity. These prevalence variations may reflect differences in both environmental and genetic factors affecting clefting risk.