Complex segregation analysis in a sample of consecutive newborns with cleft lip with or without cleft palate in Italy

Epidemiological characteristic of Orofacial clefts and its associated congenital anomalies: retrospective study

BACKGROUND

To evaluate the relationship between gender, ethnicity/citizenship, clinical phenotype, total prevalence, and the various congenital malformations associated with oral clefts (OC) in Italy across the period 2001-2014.

METHODS

A retrospective analysis (2001-2014) was conducted based on the National Congenital Malformation Registries network of Italy (Emilia-Romagna Registry of Birth Defects [IMER] and Registro Toscano Difetti Congeniti [RTDC]), which were analyzed to investigate time trends, geographical/ethnic clusters, topography, sex ratio, and associated congenital anomalies of OC phenotypes.

RESULTS

Among 739 registered cases, 29.8% were syndromic or had multi-malformed associated anomalies, compared with 70.2% having isolated orofacial cleft. Cleft lip (CL) was observed in 22%, cleft palate (CP) in 40%, and cleft lip and palate (CLP) in 38% of live births, stillbirths, and terminations of pregnancy for fetal anomaly cases. Other associated conditions were major anomalies of cardiovascular defects (39%), followed by defects of the limbs (28%), neuroectodermal defects (23%), and urogenital malformations (10%). Male-to-female sex ratio was 1:1.14 in CP, 1.22:1 in CL, and 1.9:1 in CLP. Foreigners were represented by 29% from Southeast Asia, 25% from Balkans, 25% from North-Central Africa, 9% from the East, 7% from Western Europe, and 5% from South America. Total prevalence of OC cases ranged from 0.9 (RTDC) to 1.1 (IMER) of 1000 births.

CONCLUSIONS

This retrospective study provides a population-based, clinical-epidemiological description of the orofacial cleft phenomenon. As a relatively frequent congenital malformation, its social and economic impact is worthy of further study. These abnormalities can cause significant problems that may be solved or minimized by early diagnosis and treatment.

Genetics of nonsyndromic cleft lip with or without cleft palate: is there a Mendelian sub-entity?

The mode of inheritance of nonsyndromic cleft lip with or without cleft palate (NSCLP) is still a matter of dispute. We performed segregation analysis on three data sets of families ascertained through an affected child with NSCLP. The first two data sets were selected in France and were pooled for a global analysis. No major gene effect could be evidenced in spite of a very large number of families (666 pedigrees including 719 nuclear families). The third data set was British and consisted of three-generation families including the offspring of probands. A major gene effect, as well as a strong residual multifactorial component, were highly significant and we could show that this evidence almost entirely came from the information on probands' offspring. We conclude that a mixture of monogenic and of multifactorial cases is probably the best explanation for the observations made in this study. Analyses performed in pedigrees with multiple cases closely related might allow reducing heterogeneity and help identifying those Mendelian sub-entities.

Genetic analysis of candidate loci in non-syndromic cleft lip families from Antioquia-Colombia and Ohio

Non-syndromic cleft lip with or without cleft palate (CL/P) is a genetically complex birth defect, with a prevalence from 1/500 to 1/1,000 live births. Evidence from linkage and linkage disequilibrium studies is contradictory suggesting that heterogeneity between study populations may exist. A recent report of a genome widescan in 92 sib pairs from the United Kingdom revealed suggestive linkage to 10 loci [Prescott et al., 2000]. The purpose of this study is to replicate those results and evaluate additional candidate genes in 49 Colombian and 13 Ohio families. Genotypes were obtained for STRPs at 1p36, 2p13 (TGFA), 4p16 (MSX1), 6p23-25, 6q25-27, 8q23-24, 11p12-q13, 12q13, 14q24 (TGFB3), 16q22-24, 17q12-21 (RARA), and Xcen-q21. Linkage was performed using parametric (dominant and recessive models) and non-parametric (GenehunterNPL and SimIBD) analyses. In addition, heterogeneity was analyzed using GenehunterHLOD, and association determined by the TDT. The Colombian families showed significant SimIBD results for 11p12-q13 (P = 0.034), 12q13 (P = 0.015), 16q22-24 (0.01), and 17q12-21 (0.009), while the Ohio families showed significant SimIBD results for 1p36 (P = 0.02), TGFA (P = 0.005), 6p23 (P = 0.004), 11p12-q13 (P = 0.048) and significant NPL results for TGFA (NPL = 3.01, P = 0.009), 4p16 (MNPL = 2.07, P = 0.03) and 12q13 (SNPL = 3.55, P = 0.007). Significant association results were obtained only for the Colombian families in the regions 1p36 (P = 0.046), 6p23-25 (P = 0.020), and 12q13 (P = 0.046). In addition several families yielded LOD scores ranging from 1.09 to 1.73, for loci at 4p16, 6p23-25, 16q22-24, and 17q13. These results confirm previous reports for these loci. However, the differences between the two populations suggest that population specific locus heterogeneity exists. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299/suppmat/index.html.

Nonsyndromic cleft lip and palate: four chromosomal regions of interest

Nonsyndromic cleft lip with or without cleft palate (NSCLP), a common birth defect affecting 1/700 live births and 4,000 newborns/year in the United States, is associated with short and long-term morbidity. As such, it has significant impact on the health care system. NSCLP is a complex disorder that results from the interaction of genetic and environmental factors that are slowly being defined. Genomic scans have suggested a number of regions that may contain NSCLP loci. In this study, we have evaluated regions identified by a previously published genomic scan of affected sib-pairs and have found evidence of association in sixty-five multiplex families for eight chromosomal regions. Four of these regions, 2q37, 11p12-14, 12q13, and 16p13, have also been identified in second genomic scan of multiplex families from China. One region, defined by D11S1392, gave evidence suggesting the presence of an NSCLP locus in all three studies. Altogether, these results suggest chromosomal regions that should be targeted in order to identify NSCLP loci.

Complex segregation analysis of 1,792 cleft lip and palate families in South America: 1967-1997

Although several studies have demonstrated familial aggregation of nonsyndromic cleft lip with or without cleft palate (CL/P), its model of inheritance remains uncertain. We report the results of complex segregation analysis performed in South American families with a newborn affected with CL/P. Families of 1,792 consecutive newborns affected with CL/P and registered during the period 1967 to 1997 were studied. A model that did not include a major locus was the best-fitting model for CL/P families. This result is in agreement with previous studies which showed a significant association of several putative susceptibility loci and CL/P, indicating that the genes involved in CL/P are likely to have only a very modest impact on disease risk.

Evidence that BCL3 plays a role in the etiology of nonsyndromic oral clefts in Brazilian families

The BCL3 gene has been considered a susceptibility locus for nonsyndromic cleft lip with or without cleft palate (NSCL/P), based on association and linkage studies in some populations. We evaluated an intragenic marker at the BCL3 gene and the microsatellite D19S178 (1.1 cM distant from the BCL3 gene) among 98 infants born with NSCL/P and their parents, using the transmission disequilibrium test (TDT) and a method for haplotype analysis. Our analysis, based on BCL3 alleles, revealed the existence of a marginal association of allele 135pb of the BCL3 gene with NSCL/P (chi(2)=3.60; P=0.058; 1 df), with a major effect in female (chi(2)=5.77; P=0.016; 1 df) and in familial cases (chi(2)=3.79; P=0.051; 1 df). However, the haplotype analysis detected no significant segregation distortion, even if the alleles of the D19S178 were grouped into two classes. These findings support previous findings that BCL3 plays a role in the etiology of NSCL/P as an allele of low penetrance or as a modifier locus. We hypothesize that there might be more than one mutation in this gene associated with NSCL/P, or alternatively, that more than one mutation has arisen associated with the 135-bp allele. Genet. Epidemiol. 23:364-374, 2002

Nonsyndromic cleft lip with or without cleft palate in China: assessment of candidate regions

OBJECTIVE

Although Asians have the highest birth prevalence of oral-facial clefts, the majority of gene mapping studies of cleft lip with or without cleft palate (CL/P) have been in European or American Caucasians. Therefore, the objective of this study of Chinese families was to evaluate linkage and association between CL/P and 10 genetic markers in five chromosomal regions that have shown positive results in Caucasians.

SETTING

Families were ascertained through nonsyndromic CL/P surgical probands from hospitals throughout Shanghai, China.

PARTICIPANTS

Study participants included 671 individuals from 60 families with two or more members affected with oral-facial clefts. Of the 671 total individuals, 145 were affected.

RESULTS

Ten markers from chromosomes 2, 4, 6, 17, and 19 were assessed (TGFA, MSX1, D4S194, D4S175, F13A1, GATA185H, D17S250, D17S579, D19S49, APOC2). LOD scores were calculated between each of the 10 markers and CL/P as well as model-free statistics of linkage (SimIBD) and association (TDT). None of the markers showed significantly positive LOD scores with CL/P. A significantly positive result (p =.01) was seen using SimIBD for APOC2 on chromosome 19, and a positive TDT result (p =.004) was obtained for D19S49, near APOC2.

CONCLUSIONS

This is the first gene mapping study of CL/P in China. These results indicate that most of the genetic regions with positive results in Caucasian families may not be involved in CL/P found in China, although there is some positive evidence for the candidate region on chromosome 19.

Linkage analysis of candidate regions in Swedish nonsyndromic cleft lip with or without cleft palate families

OBJECTIVE

To analyze linkage of five candidate regions for nonsyndromic cleft lip with or without palate (CLP) on chromosome 2p13, 4q, 6p23, and 19q13; in addition chromosome 1q32, the locus for van der Woude syndrome, on Swedish CLP families.

DESIGN

Three to five linked microsatellite markers were selected from each candidate region. Polymerase chain reaction (PCR) with fluorescent-labeled microsatellite markers was performed on DNA samples from the participating families. Electrophoresis of the PCR products was performed on a laser-fluorescent DNA sequencer. The genotype data were analyzed with multipoint linkage analysis. Modes of inheritance tested included two autosomal dominant, an autosomal recessive, and a nonparametric model. Multipoint logarithm of odds (LOD) scores were also calculated by assuming genetic heterogeneity.

PARTICIPANTS

Nineteen Swedish multigenerational families with at least two first-degree relatives affected with CLP. Greater than 50% of the families studied show vertical transmission of the clefting phenotype and both inter- and intrafamilial variability were noted.

RESULTS

Cumulative multipoint LOD scores for the whole group of families calculated under autosomal dominant modes of inheritance were negative in all regions and less than -2 except chromosome 6p23. LOD scores calculated under recessive inheritance and the nonparametric model were inconclusive. There was no significant evidence of genetic heterogeneity among the sample group.

CONCLUSIONS

The group of Swedish CLP families did not demonstrate significant linkage to any of the five candidate regions examined. This might suggest a new but yet unknown CLP locus or loci in this family group. However, because linkage could not be excluded in some individual families, they should still be tested with candidate genes from these regions.

Genetics of nonsyndromic cleft lip and palate: a review of international studies and data regarding the Italian population

The aims of this review are (1) to illustrate current knowledge of the mode of inheritance and the loci involved in the cleft lip and palate and (2) to summarize the results of our investigations, which were carried out in Italy. It is well established that nonsyndromic cleft of the lip with or without the palate (CL+/-P) and cleft palate only (CPO) are separate entities. Genetic heterogeneity has been observed in CL+/-P, which involves different chromosome regions, mainly 6p23 (OFC1), 2q13 (OFC2), and 19q13.2 (OFC3), as well as other loci, such as 4q25-4q31.3 and 17q21. Furthermore, an interaction between different genes has been suggested in the oligogenic model. In one case at least, an OFC1 and OFC2 interaction has been demonstrated. The mode of inheritance of CPO is compatible with a recessive single major gene model, while an association with a candidate gene, mapping on the chromosome region 2q13/TGFalpha, remains to be confirmed.

Linkage analysis in a large Brazilian family with van der Woude syndrome suggests the existence of a susceptibility locus for cleft palate at 17p11.2-11.1

van der Woude syndrome (VWS), which has been mapped to 1q32-41, is characterized by pits and/or sinuses of the lower lip, cleft lip/palate (CL/P), cleft palate (CP), bifid uvula, and hypodontia (H). The expression of VWS, which has incomplete penetrance, is highly variable. Both the occurrence of CL/P and CP within the same genealogy and a recurrence risk <40% for CP among descendants with VWS have suggested that the development of clefts in this syndrome is influenced by modifying genes at other loci. To test this hypothesis, we have conducted linkage analysis in a large Brazilian kindred with VWS, considering as affected the individuals with CP, regardless of whether it is associated with other clinical signs of VWS. Our results suggest that a gene at 17p11.2-11.1, together with the VWS gene at 1p32-41, enhances the probability of CP in an individual carrying the two at-risk genes. If this hypothesis is confirmed in other VWS pedigrees, it will represent one of the first examples of a gene, mapped through linkage analysis, which modifies the expression of a major gene. It will also have important implications for genetic counseling, particularly for more accurately predicting recurrence risks of clefts among the offspring of patients with VWS.

Suggestive linkage between markers on chromosome 19q13.2 and nonsyndromic orofacial cleft malformation

Nonsyndromic cleft lip with or without cleft palate (OFC) is a common birth defect that has genetic bases. The nature of the genetic contribution is still to be clarified; however, some chromosome regions and candidate genes have been proposed for this malformation. We examined linkage between BCL3, a proto-oncogene located in 19q13.2, and OFC in a sample composed of 40 multiplex pedigrees using both nonparametric and parametric methods. The affected pedigree member statistics and the transmission disequilibrium test supported a role for BCL3 in causing OFC, while no evidence of linkage or genetic heterogeneity was found with the lod score method.

A locus in 2p13-p14 (OFC2), in addition to that mapped in 6p23, is involved in nonsyndromic familial orofacial cleft malformation

An allelic association between the transforming growth factor alpha gene (TGFA) situated in the chromosome 2p13 region and nonsyndromic cleft lip with or without cleft palate, also named orofacial cleft (OFC), was found in several population studies. However, no linkage between gene and malformation has shown up until now, probably due to the presence of genetic heterogeneity and the small sample size analyzed. Previously, we employed a collection of 38 OFC families to demonstrate linkage to the 6p23 chromosome region with the presence of genetic heterogeneity. In the present study we tested whether, in the same sample, linkage between OFC and markers on 2p13 could be determined. Evidence for genetic heterogeneity in our family set was apparent, by both pairwise and multipoint linkage analyses. Moreover, lod scores > 3 were found for marker D2S378 when families linked to the 6p23 markers were analyzed. Taken together these results indicate a role for the TGFA, or for another gene physically close to it, and suggest an interaction between two different genes, OFC1 and OFC2, mapped in 6p23 and 2p13, respectively, in the development of the cleft.

Genes for asthma? An analysis of the European Community Respiratory Health Survey

Besides environmental triggers, a family history of asthma is a strong risk factor for the development of asthma in offspring. The pooled data from 13,963 interviews of randomly selected, 20 to 48 yr-old participants from the 30 centers of the European Community Respiratory Health Survey (ECRHS) were analyzed with conventional logistic regression and a Class A regressive model adapted for the segregation of various transmission modes in families. The asthma prevalence in the interviewed index generation was 6.9% (95% confidence interval [CI]: 6.5 to 7.3), and in the parent generation was 6.1% (5.8 to 6.4). As with asthma prevalence, the risk of a subject having asthma if a parent had asthma also had a large geographic variation across the survey centers. The mean risk if a father had asthma was 2.9 (2.4 to 3.5), and If the mother had asthma was 3.2 (2.6 to 3.9). The risk increased to 7.0 (3.9 to 12.7) if both parents were affected. For developing extrinsic asthma, extrinsic asthma in any parent was a greater risk factor (4.9 [3.9 to 6.0]) than intrinsic asthma of the parent (1.5 [0.8 to 2.6]), and the risk for women was slightly higher than that for men (4.3 [3.3 to 5.5] versus 3.6 [2.6 to 5.0]). Applying different segregation models, only a model for a two-allele gene with a codominant inheritance could not be rejected, assuming a major gene with a population frequency of 24.2%. Further results make a multilocus/threshold model likely. In conclusion, a history of asthma in parents is a strong risk factor for asthma in the offspring. Under the assumptions of the applied segregation analysis, at least one major gene exists which could be a gene involved also in allergy. However, asthma is not fully described by a single-gene model. The risk for asthma varies within the European countries, and should be seen in the context of a complex genetic and environmental pathophysiology.

Maternal cigarette smoking and oral clefts: a meta-analysis

OBJECTIVE

A meta-analysis was performed to estimate the association between maternal cigarette smoking and the risk of having a child with a nonsyndromic oral cleft (NSOC).

DESIGN

Studies published from 1966 through 1996 were retrieved using MEDLINE, Current Contents, bibliographies, and other sources. MEDLINE and Current Contents search terms included "oral clefts," "cigarette smoking," "birth defects," and "congenital malformations." Cohort and case-control studies that enrolled oral cleft patients [cleft lip with or without cleft palate (CL/P), cleft palate (CP), or both] and controls, and presented information on maternal cigarette exposure during pregnancy were included in the analysis. Descriptive and outcome data from each study were independently abstracted by two authors.

RESULTS

The overall odds ratio of the 11 studies satisfying criteria was 1.29 [95% confidence interval (CI), 1.18 to 1.42] for CL/P and 1.32 (95% CI: 1.10 to 1.62) for CP, indicating a small increase risk of having a child with either a CL/P or a CP for mothers who smoke during the first trimester of the pregnancy.

CONCLUSIONS

These analyses suggest a small but statistically significant association between maternal cigarette smoking during the first trimester of gestation and increased risk of having a child with a CL/P or CP.

Congenital malformations and maternal occupation: a registry based case-control study

OBJECTIVES

To investigate the relations between congenital malformations and maternal occupation during pregnancy with a registry based case-control study.

METHODS

Analysis was performed on data derived from the Florence Eurocat registry surveillance programme. The study included cases with isolated conditions, including chromosomal anomalies (n = 1351), cases with multiple anomalies registered during the 1980-91 period (n = 440), and babies with no congenital malformations recognised at birth who were born from 1982 to 1989 and selected as controls (n = 3223). 11 categories were defined, 10 including cases with isolated malformations and one for cases with multiple congenital anomalies. Four categories of maternal occupation were selected for the study. Odds ratio (OR) values were adjusted for maternal origin, maternal and paternal education, number of previous live births, illness during pregnancy, and maternal age when the group of chromosomal anomalies was analysed.

RESULTS

A notable and significant association between oral clefts and mothers involved in leather and shoe manufacturing was found (adjusted OR 3.9; 99% confidence interval (99% CI) 1.5 to 9.8) and the risk consistently increased when considering cases with isolated cleft palate separately (OR 5.4; 95% CI 1.8 to 13.4). Moreover, a significant risk was identified for the association between multiple anomalies and textile dye workers (adjusted OR 1.9; 99% CI 1.0 to 3.8).

CONCLUSIONS

This study indicates a notable, significant relation between maternal occupation as a pelt or leather worker and orofacial clefts in offspring. This finding is in agreement with the suggested inheritance models. The dilution effect due to studying large and heterogeneous groups of workers and occupations limits the value of the study; but it provides a good example of the use of a large database to search for teratogenic risk with the aid of malformation registries.

Genetics of nonsyndromic oral clefts revisited

Nonsyndromic oral clefts are among the most common birth defects, affecting approximately 1 in 1000 Caucasian newborns. In recent decades, many investigators have used genetic and epidemiologic methods to identify etiologic factors, but results have often been inconclusive or contradictory. Etiologic heterogeneity is undoubtedly a major component in these birth defects, and there may not be a single answer to this problem. Here, we describe the main features of published studies pointing out their strengths and limitations. Additionally, we give insight into current methods for detecting the presence of interaction between genetic markers and environmental exposures in the etiology of oral clefts.