Lack of association between IRF6 polymorphisms (rs2235371 and rs642961) and non‐syndromic cleft lip and/or palate in a Brazilian population

Oral Diseases (2010) 16 , 193–197 Background: Interferon regulatory factor 6 (IRF6) gene has emerged as a potential susceptibility gene for non‐syndromic cleft lip and/or palate (NSCL/P) in different populations. The aim of this study was to determine the association of IRF6 rs2235371 and rs642961 polymorphisms with NSCL/P in a Brazilian population. Methods: Two hundred and twenty‐eight patients affected by NSCL/P and 126 healthy individuals were genotyped by polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) assay. Results: Overall genotype distributions of rs2235371 and rs642961 polymorphisms were as expected by Hardy‐Weinberg equilibrium test. The rs2235371 polymorphic genotype GA was identified in 10.1% of the patients with NSCL/P and in 10.3% of the control group, revealing no statistical difference. Similarly, the frequency of rs642961 minor genotypes (GA and AA) was quite similar between control group (28.6%) and NSCL/P group (25.4%), without significant difference. Conclusion: Our findings are consistent with a lack of involvement of IRF6 rs2235371 and rs642961 polymorphisms in the NSCL/P pathogenesis in the Brazilian population.     

Genetic variation of IRF6 and TGFA genes in an HIV‐exposed newborn with non‐syndromic cleft lip palate

We present here the first reported case of a non‐syndromic cleft lip and palate (NSCLP) in an HIV‐exposed newborn of a mother on antiretroviral therapy (ART) in Indonesia. Genetic testing was performed to confirm a suspected genetic condition. Genomic DNA was extracted from the blood, and genetic variations of the interferon regulatory factor 6 (IRF6) rs642961 (Mspl) (G>A) and transforming growth factor alpha (TGFA) BamHI (rs11466297, A>C) and RsaI (rs3732248, C>T) were performed by PCR‐RFLP and IRF6 gene analysis by PCR sequencing. Genotyping of DNA sequence variants in the IRF6 gene showed both parents had genotype GA, while the child had genotype GG (genotype wild type). There was no difference observed in the TGFA BamHI gene variant between the child and her mother and father that were wild‐type polymorphisms (normal), while the Rsa1 polymorphisms of them were heterozygotes. A genetic variant of IRF6 might be a protective factor for NSCLP, while Rsa1 gene variant (A) allele can be considered to be the risk factor associated with NSCLP development. This case report also highlights the possible etiologic role of ART in NSCLP; therefore, early control of adverse effects of ART might be an important factor in decreasing the incidence of the congenital anomalies in HIV‐infected children.     

IRF6 gene variants in Central European patients with non‐syndromic cleft lip with or without cleft palate

Variants in the interferon regulatory factor 6 (IRF6) gene have repeatedly been associated with non‐syndromic cleft lip with or without cleft palate (NSCL/P). A recent study has suggested that the functionally relevant variant rs642961 is the underlying cause of the observed associations. We genotyped rs642961 in our Central European case–control sample of 460 NSCL/P patients and 952 controls. In order to investigate whether other IRF6 variants contribute independently to the etiology of NSCL/P, we also genotyped the non‐synonymous coding variant V274I (rs2235371) and five IRF6‐haplotype tagging single nucleotide polymorphisms (SNPs). A highly significant result was observed for rs642961 (P = 1.44 × 10^?6) in our sample. The odds ratio was 1.75 [95% confidence interval (CI): 1.38–2.22] for the heterozygous genotype and 1.94 (95% CI: 1.21–3.10) for the homozygous genotype, values that are similar to those reported in a previously published family‐based study. Our results thus confirm the involvement of the IRF6 variant, rs642961, in the etiology of NSCL/P in the Central European population. We also found evidence suggestive of an independent protective effect of the coding variant V274I. In order to understand fully the genetic architecture of the IRF6 locus, it will be necessary to conduct additional SNP‐based and resequencing studies using large samples of patients.     

Epidemiological and genetic study of 121 cases of oral clefts in Kuwait

Authors – S Al‐Bustan, M El‐Zawahri, A Al‐Adsani, R Bang, I Ghunaim, B Maher, S Weinberg, M Marazita Aim – The aim of the study was to ascertain some epidemiological factors such as sex and consanguinity that may be associated with cleft lip with or without cleft palate (CL ± CP) in Kuwait as well as to conduct genetic segregation analysis of these families. Setting and sample population – A total of 113 families ascertained through 121 CL ± CP and CP surgical probands in Kuwait. The frequencies of cleft types and the epidemiological variables were calculated using SPSS version 5.0 software. Chi‐square for goodness‐of‐fit test was used to test the significance of the associated epidemiological variables to facial clefts. Genetic segregation analysis was performed on 76 families with extended pedigrees and included only those with non‐syndromic CL ± CP (NS CL ± CP). Major locus segregation analysis was used to fit models to the observed family patterns under Class A regressive models as implemented by REGD routine in S.A.G.E. release 4.0. A test for heterogeneity was also conducted to complete data set in addition to two subsets: Arabs and nomads. Results – Of the 121 patients, 34(28.1%) had CP, 30(24.8%) had CL and 57 (47.1%) had CL + CP. The male to female ratio was 0.89 for CP, 1.14 for CL, 1.35 for CL + CP and 1.2 for all the clefts. The percentage of consanguineous families among those with a positive family history (60%) was not significantly different from that of the general population (54.3%), whereas for all the families with clefts the percent consanguineous was significantly lower (38%). No evidence of heterogeneity in the results between the Arab and nomad subsets was observed. The results for the major locus segregation analysis were inconclusive. Conclusion – No definite association was observed between consanguinity and the occurrence of facial clefts in Kuwait. General transmission models in the full data set showed no evidence of heterogeneity in the results between the Arab and nomad subsets.     

5,10‐Methylenetetrahydrofolate reductase single nucleotide polymorphisms and gene–environment interaction analysis in non‐syndromic cleft lip/palate

Non‐syndromic cleft lip/palate (NSCL/P) is a common congenital defect in Mexico. Periconceptional intake of folic acid (FA) may reduce the risk of this malformation. Although the 5,10‐methylenetetrahydrofolate reductase (MTHFR) enzyme participates in folate metabolism, several studies failed to find any association between NSCL/P and the MTHFR C677T and A1298C polymorphisms. However, interactions among NSCL/P, MTHFR gene polymorphisms, and FA intake have not been explored in Mexican populations. This case–control study included 132 patients with NSCL/P and 370 controls from Mexico City. Maternal FA consumption during pregnancy was examined, as were the MTHFR C677T and A1298C polymorphisms and gene–FA interactions. Maternal FA intake during the periconceptional period was lower in cases (1.5%) than in controls (13%), with the risk of delivering a child with NSCL/P lower in mothers who consumed FA (OR = 0.29, 95% CI: 0.19–0.44). In addition, the risk of NSCL/P was lower in children with the TT than the CC genotype of MTHFR C677T (OR = 0.39, 95% CI: 0.23–0.68), after Bonferroni correction and exclusion of stratification. No evidence of gene–FA interaction was found. These results indicate that maternal FA intake and the TT genotype of the MTHFR C677T polymorphism in children independently reduced the risk of NSCL/P in our population.     

Dental age and asymmetry in the formation of mandibular teeth in twins concordant or discordant for oral clefts

Abstract – The aims of this investigation were: 1) to study the effects of zygosity and the type of cleft on dental age in pairs of twins concordant or discordant for oral clefts, 2) to compare dental age in the twins with that in a population of normal Finnish children, and 3) to study asymmetry in the formation of mandibular teeth with regard to zygosity and the type of cleft. Twenty-two pairs of twins (8 mono- and 14 dizygotic) and one set of monozygotic triplets concordant or discordant for cleft lip (CL), cleft palate (CP), or both (CLP) were investigated. Four of eight mono- and 12 of 14 dizygotic pairs were discordant for clefts. An orthopantomogram of both twins was taken on the same day. In 7 of the 8 monozygotic (88%) and in 4 of the 14 dizygotic (29%) pairs, the dental age was the same in both twins. Of the 12 pairs discordant for clefts, the dental age of the twin with cleft was delayed in 5, advanced in 3, and the same in 4 compared with that of the twin without a cleft. The means of chronologic age and dental age were counted separately for the cleft subgroups and the non-cleft (NONC) group. The dental age was advanced in the CL twins and in the NONC twins, and was the same as chronologic age in the CP twins, but it was delayed in the CLP twins. Asymmetric formation of the 14 mandibular teeth (mostly the second premolars) was encountered in 3 of 8 CLP, in 3 of 18 CP, in 1 of 16 NONC, and in none of 5 CL children. The great similarity in tooth formation among the monozygotic twins indicates strong genetic control of dental maturation in twins concordant and also discordant for cleft.     

Prevalence of oral trauma in children with bilateral clefts

Abstract –  The main object of this study is to analyze the prevalence of oral trauma in subjects with complete bilateral clefts, with anterior projection of the premaxilla. A total of 106 children aging 6 months to 9 years were analyzed. The caretakers answered a specific questionnaire, in order to report the presence or absence of trauma to the soft and/or hard tissues of the child's mouth. Whenever there was a history of trauma, the patients were submitted to clinical examination. The prevalence of oral trauma was 53%, being 91% of soft tissue lesions, 8.9% of avulsion, 7% of luxation and 1.8% of intrusion. For the males, the prevalence was 56% and for the females it was 47%, with no statistical significance. Regarding the following aspects:period of time spent with the parents and at school, and presence or absence of siblings, no statistical difference could be found. Among the traumatized individuals, 80% aged less than 3 years by the moment of the trauma, 89% suffered the trauma at home, 75% presented lesions in the soft tissue at the premaxilla, 16% in the maxillary incisors, and 8.9% presented lesions in both structures. It was noticed that 45% of the permanent incisors that succeeded the traumatized deciduous teeth presented alterations, being 48% of structure and 52% of structure and position. The prevalence of trauma in this sample was superior to that observed in the literature, without any positive associations between the evaluated aspects. These results suggest that the projection of the premaxilla brings about a higher risk of oral trauma around this area.     

Epidemiology underpinning research in the aetiology of orofacial clefts

INTRODUCTION: Epidemiological information gathered through birth defects surveillance is an important adjunct to carrying out clinical and aetiological research. Information on the incidence in the population, causative risk factors and providing baseline data prior to intervention are all important elements. Under the auspices of the World Health Organisation, it was agreed that a global registry and database on craniofacial anomalies should be created and this, the International Database on Craniofacial Anomalies (ICDFA) was designed to gather information on craniofacial abnormalities from existing birth defects registries and databases around the world to become a resource underpinning research. There are currently 62 registries covering 2 million births per year contributing to a database along with information on the size and type of studies used to collect the information, any variation in ascertainment and on the inclusion of syndromes and associated abnormalities. GENERATION OF HYPOTHESES: From the epidemiological data collected it is possible to carry out meta-analysis and to search for trends and consistencies in the data that enable hypothesis to be generated. Issues such as geographical distribution, ethnicity, gender, associated abnormalities and clefts in stillbirths can all be examined in a meta-analytical approach. Collection of information on risk factors such as maternal illnesses, medications, lifestyle factors, nutrition and perhaps occupational exposures enables investigation into environmental contribution to causality and genetic predisposition. A range of techniques are currently being used to identify new candidate genes and ultimately it will be necessary to test genetic and environmental hypothesis in the context of human population studies. CONCLUSIONS: It is only by consistency of association between different populations with different gene pools and maternal exposures, lifestyles, nutrition etc that conclusive evidence regarding causality will be found. It is therefore essential, and a major objective of the WHO that international multicentre collaborative studies are setup to gather the appropriate evidence and improve knowledge and the cause of birth defects in general and orofacial clefts in particular, with the ultimate humanitarian and scientific objective of the WHO being primary prevention. CLINICAL UTILITY AND IMPLICATIONS: This IDCFA project fulfils three basic objectives namely to enable global surveillance of CFA; to create online access to those who wish to contribute to the IDCFA, and to develop an online directory of resources on craniofacial anomalies for the support of research and improving quality of care. The next steps for IPDTOC are to expand the number of participating registries and to actively collect data on other craniofacial birth defects.     

Studies of genes involved in craniofacial development and tumorigenesis: FGF3 contributes to isolated oral clefts and may interact with PAX9

Objective. Previous studies suggest individuals born with oral clefts and their families have a higher susceptibility for cancer, which raises the hypothesis that these two conditions share common molecular pathways. This study evaluated the association between oral clefts and polymorphisms in genes that play a role in craniofacial and tumor development. Materials and methods. Four hundred and ninety-seven subjects born with oral clefts and 823 unaffected subjects were recruited. Twenty-nine markers in 13 genes were genotyped by the Taqman method. Chi-square was used to compare allele and genotype frequencies. Bonferroni correction for multiple testing was used and the established alpha was 0.0003. This study also used logistic regression to test if genetic variants were associated with oral clefts using positive family history of cancer and age as covariates. Results. There was no association between family history of cancer and oral clefts (p = 0.51). None of the 1320 study participants had a diagnosis of cancer at the time of participation in the study. The marker rs4980700 in FGF3 was associated with oral clefts (p = 0.0002). Logistic regression analysis also provided evidence for gene–gene interaction between FGF3 (rs4980700) and PAX9 (rs2073242), increasing the risk for isolated oral clefts (p = 0.0003). Conclusion. FGF3 is associated with oral clefts and may interact with PAX9.     

中国人群非综合征性唇腭裂患者IRF6基因突变检测

目的 探讨干扰素调节因子6(interferon regulatory factor 6, IRF6) 在非综合征性唇腭裂(non-sydromic cleft lip and/or cleft palate,NSCL/P)患者中的突变情况。方法：收集119例NSCL/P患者及288名健康人对照样本的外周血血样并提取DNA。在IRF6基因的全部外显子分别设计引物,PCR扩增其序列,通过测序找出IRF6基因突变,并将这些突变在对照样本中进行验证。结果：共发现5种在正常人中没有的突变,其中4种是新发现的突变。结论：IRF6基因突变在中国人群中参与了非综合征唇腭裂疾病的发生。     

Susceptibility locus for non‐syndromic cleft lip with or without cleft palate on chromosome 10q25 confers risk in Estonian patients

Nikopensius T, Birnbaum S, Ludwig KU, Jagomägi T, Saag M, Herms S, Knapp M, Hoffmann P, Nöthen MM, Metspalu A, Mangold E. Susceptibility locus for non‐syndromic cleft lip with or without cleft palate on chromosome 10q25 confers risk in Estonian patients. Eur J Oral Sci 2010; 118: 317–319. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci Non‐syndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common birth defects and has a multifactorial etiology that includes both genetic and environmental factors. Recently, two novel susceptibility loci and three suggestive loci for NSCL/P were identified by a genome‐wide association scan (GWAS) in a German population with subsequent independent replication in a mixed European population. The aim of the present study was to investigate whether these newly detected loci confer similar effects in the North‐East European Baltic population. A total of 101 NSCL/P patients and 254 controls from Estonia were included. A significant association was observed for rs7078160 (P = 0.0016) at chromosome 10q25, which confirms the association of this locus with NSCL/P in the Baltic population. No significant association was found for the other four loci, a result that may have been attributable to the limited power of the sample.