DNA-sequence variants associated with IRF6 are major contributors to cleft lip, with or without cleft palate. The contribution of variants in single genes to cleft lip or palate is an important consideration in genetic counseling.

Orofacial clefts (OFCs), which include non-syndromic cleft lip with or without cleft palate (CL/P), are among the most common birth defects in humans, affecting approximately 1 in 700 newborns. CL/P is phenotypically heterogeneous and has a complex etiology caused by genetic and environmental factors. Previous genome-wide association studies (GWASs) have identified at least 15 risk loci for CL/P. As these loci do not account for all of the genetic variance of CL/P, we hypothesized the existence of additional risk loci. We conducted a multiethnic GWAS in 6480 participants (823 unrelated cases, 1700 unrelated controls and 1319 case-parent trios) with European, Asian, African and Central and South American ancestry. Our GWAS revealed novel associations on 2p24 near FAM49A, a gene of unknown function (P = 4.22 × 10), and 19q13 near RHPN2, a gene involved in organizing the actin cytoskeleton (P = 4.17 × 10). Other regions reaching genome-wide significance were 1p36 (PAX7), 1p22 (ARHGAP29), 1q32 (IRF6), 8q24 and 17p13 (NTN1), all reported in previous GWASs. Stratification by ancestry group revealed a novel association with a region on 17q23 (P = 2.92 × 10) among individuals with European ancestry. This region included several promising candidates including TANC2, an oncogene required for development, and DCAF7, a scaffolding protein required for craniofacial development. In the Central and South American ancestry group, significant associations with loci previously identified in Asian or European ancestry groups reflected their admixed ancestry. In summary, we have identified novel CL/P risk loci and suggest new genes involved in craniofacial development, confirming the highly heterogeneous etiology of OFCs.

Definition: ECLAMC (‘Estudio Colaborativo Latino Americano de Malformaciones Congénitas’) is a program for the clinical and epidemiological investigation of risk factors in the etiology of congenital anomalies in Latin-American hospitals, using a case-control methodological approach. It is a voluntary agreement among professionals lacking institutional base as well as designated budgets. ECLAMC has been usually funded by research-funding agencies rather than public health ministries. The National Research Councils of Argentina and Brazil have been the main sources of support during its 36 years of existence. Since vital and health statistics are unreliable in South America, ECLAMC collects all the information required for the denominators in a hospital-based sample of births. ECLAMC can be defined as a continental network of persons interested in research and prevention of birth defects. History and Evolution: From the institutional point of view, ECLAMC has had headquarters in diverse centers of Argentina and Brazil, but always as an independent research project, without a defined administrative link. ECLAMC began operating in 1967, as an investigation limited to the city of Buenos Aires, Argentina, and it gradually expanded until covering all the 10 countries of South America as well as Costa Rica and the Dominican Republic. Even though ECLAMC has maintained essentially the same original experimental design since 1967, due to the data accumulated by the program, the increasing experience as well as the development in science, technical modifications occurred including a DNA bank and a fully informatized data handling system. Since 1974 ECLAMC has been a founder member of the International Clearinghouse for Birth Defects Monitoring Systems; since 1994 a WHO Collaborating Center for the Prevention of Congenital Malformations, and since 2000 a collaborating member of the NIH Global Netwok for Women’s and Children’s Health Research. Methodology: The maternity hospital network of ECLAMC examines around 200,000 births per year. All major and minor anomalies diagnosed at birth in infants weighing 500 g or more are registered according to a manual of procedures. The next non-malformed baby of the same sex born in the same hospital is selected as a control subject for each case. Thus, a one-to-one healthy control group matched by sex, time and place of birth is obtained. As a system of epidemic surveillance, ECLAMC systematically observes the fluctuations in the frequencies of different malformations and, in the case of an alarm for a probable epidemic of a given malformation, at a given moment, and given area, it acts to identify its cause. As termination of pregnancy has severe legal restrictions in South America, prevention of birth defects should concentrate on primary, preconceptional and tertiary measures. Tertiary measures aim to avoid complications of the affected patients from the medical, psychological, and social standpoints.

Nonsyndromic orofacial clefts (OFCs) are a heterogeneous group of common craniofacial birth defects with complex etiologies that include genetic and environmental risk factors. OFCs are commonly categorized as cleft lip with or without cleft palate (CL/P) and cleft palate alone (CP), which have historically been analyzed as distinct entities. Genes for both CL/P and CP have been identified via multiple genome-wide linkage and association studies (GWAS), however, altogether, known variants account for a minority of the estimated heritability in risk to these craniofacial birth defects. We performed genome-wide meta-analyses of CL/P, CP, and all OFCs across two large, multiethnic studies. We then performed population specific meta-analyses in sub-samples of Asian and European ancestry. In addition to observing associations with known variants, we identified a novel genome-wide significant association between SNPs located in an intronic TP63 enhancer and CL/P (p = 1.16 × 10−8). Several novel loci with compelling candidate genes approached genome-wide significance on 4q21.1 (SHROOM3), 12q13.13 (KRT18), and 8p21 (NRG1). In the analysis of all OFCs combined, SNPs near FOXE1 reached genome-wide significance (p = 1.33 × 10−9). Our results support the highly heterogeneous nature of OFCs and illustrate the utility of meta-analysis for discovering new genetic risk factors.