ICD‐10 impact on ascertainment and accuracy of oral cleft cases as recorded by the Brazilian national live birth information system

We compared Brazilian oral cleft (OC) frequencies between the population‐based Brazilian System of Live Birth (SINASC) and the hospital‐based Latin American Collaborative Study of Congenital Malformations (ECLAMC), trying to understand the paucity of cleft of lip and palate (CLP) in the first system. SINASC uses the International Classification of Disease version 10 (ICD‐10) for congenital defects coding, ECLAMC uses ICD‐8 with modifications. In SINASC, the CLP frequency was 1.7 per 10,000 (95% confidence limits 1.7–1.8), cleft lip (CL) 1.6 (1.5–1.7), and cleft palate (CP) 2.0 (1.9–2.1). In ECLAMC, the CLP frequency was 10.4 per 10,000 (9.0–12.1), CL 5.5 (4.5–6.7), and CP 4.4. (4.5–6.7). In SINASC, only 33% of the oral clefts were CLP, versus 51% in ECLAMC. Part of this discrepancy may have been due to the relative excess of CP and CL cases. Although congenital defect frequencies are usually lower in population than in hospital‐based registries, differences in the proportion of the main OC categories are not expected and are probably due to ICD‐10 coding issues, such as lumping of unilateral CL and CL without other specifications. ICD‐10 codes, whose deficiency for oral clefts is fully explained in the literature, lack modifiers for severity, or clinical subtypes. This paper shows the practical aspect of the ICD‐10 system deficiency in capturing cleft lip and palate (CLP) subtypes, as demonstrated in SINASC covering three million births per year. Such errors are expected to occur in any registry that uses the ICD‐10 coding system, and must be adjusted, given its relevance worldwide.

     

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

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. Am. J. Med. Genet. 79:42–47, 1998. © 1998 Wiley-Liss, Inc.     

Epidemiology of orofacial clefts in a Danish county over 35 years – Before and after implementation of a prenatal screening programme for congenital anomalies

In 2004 the Danish National Board of Health changed its screening recommendations. Since 2005 a first trimester screening for Down syndrome and a prenatal ultrasound screening for congenital anomalies in the second trimester of pregnancy has been offered to all pregnant women.The aim of this study was to describe the prevalence of cleft lip with or without cleft palate and cleft palate in a Danish area and to describe associated anomalies and the development in prenatal diagnosis over time. The study was based on data from the EUROCAT Registry for Funen County. The registry is based on multiple data sources and includes information about live births, fetal deaths with a gestational age >20 weeks and terminations of pregnancy after prenatal diagnosis of severe fetal anomaly. The study included all fetuses/infants out of a population of 182,907 births diagnosed with orofacial clefts born between 1980 and 2014. There were 271 cases diagnosed with cleft lip with or without cleft palate and 127 cases diagnosed with cleft palate, giving a prevalence of 14.8 per 10,000 births for cleft lip with or without cleft palate and 6.9 per 10,000 births for cleft palate. There were no significant changes in prevalence over time for the two anomalies, calculated with and without inclusion of genetic and chromosomal cases. Overall 66 cases were diagnosed prenatally (17% of total). For isolated cleft lip with or without cleft palate none of the 157 cases born before 2005 were diagnosed prenatally compared to 34 of 58 cases (59%) born in 2005–2014 (p?<?0.01). The proportion of liveborn infants with multiple congenital anomalies also changed after 2005 with 15% (39/266) of all liveborn infants with orofacial clefts born 1980–2004 having multiple anomalies compared to 7% (7/96) in 2005–2014 (p?<?0.05).The implementation of the new screening programme in 2005 has given a major change in prenatal detection rate and reduced the proportion of liveborn infants with orofacial clefts classified as multiple congenital anomaly cases. The prevalence of cleft lip with or without cleft palate was higher than reported from many other countries.     

Congenital malformations in births with orofacial clefts among 3.6 million California births, 1983-1997

Few population-based epidemiologic data are available on malformation phenotypes that co-occur with orofacial clefts. We explored the occurrence of structural congenital malformations in offspring with cleft palate (CP) and in offspring with cleft lip with or without CP (CLP), using data from a population-based active surveillance system. Ascertainment was performed among 3548991 liveborn and 23239 stillborn offspring of California women who delivered in nonmilitary hospitals during the period, 1983-1997. Structural congenital malformations were found in 91888 births. Among them, 2343 had CP and 4072 had CLP. Malformations were grouped according to 3- and 4-digit codes of the British Pediatric Association (BPA). Prevalences of each malformation grouping, defined by these codes, were calculated among: (1). all births with CP; (2). all births with CLP; (3). all births without CP or CLP but with another structural malformation; and (4). all births in the population at risk. These various prevalence measures were the basis of estimating relative risks. Observed relative risks indicated that some phenotypes were more likely and some were less likely to co-occur with either CP or CLP, with relative risks ranging from 0.5 to 2.4. For both CP and CLP, estimated relative risks were highest for malformations involving the respiratory system and lowest for spina bifida. The exclusion of all births (n = 10702) with chromosomal anomalies from comparisons did not materially alter observed relative risk estimates. Computations extended to 4-digit level BPA codes revealed elevated risks for a number of more specific diagnoses seen within the larger (3-digit level) groupings defined as eye, ear, respiratory, upper alimentary tract, and other musculoskeletal anomalies. In this large population-based cohort of infants and fetuses with CLP or CP, we observed several noncleft malformation groupings to be more common and others to be less common in their co-occurrence with orofacial clefts relative to their co-occurrence with any other malformation. These observed patterns tended to be similar for CP and for CLP.     

High prevalence of orofacial clefts in Shanxi Province in northern China, 2003-2004

Shanxi Province in northern China has been identified as an area with the highest prevalence of neural tube defects in the world; however, few reports exist on the prevalence of orofacial clefts (OFC). We examined the prevalence of OFC and their association with selected characteristics. Data came from a population-based birth defects surveillance system in four counties of Shanxi Province. The system captures information on all live births, stillbirths of at least 20 weeks gestation, and pregnancy terminations at any gestational age after prenatal diagnosis of a birth defect. Out of 25,355 births in 2003-2004, 83 cases with orofacial clefts were identified resulting in a birth prevalence of 3.27 per 1,000. Other major external birth defects were present in 12 (14.5%) OFC cases. Cleft lip with palate (CLP), cleft lip alone (CL) and cleft palate alone (CP) accounted for 62.0%, 29.6% and 8.4% of OFC cases without additional external defects, respectively. The male to female ratio was 1.04 (95%CI: 0.67-1.60) for all OFC, 1.46 (95%CI: 0.80-2.68) for CLP, 1.23 (95%CI: 0.52-2.91) for CL, 0.46 (95%CI: 0.08-2.51) for CP without additional major external defects, and 0.31(95%CI: 0.08-1.13) for OFC with additional external defects. The prevalence of OFC without additional external defects was increased with decreased maternal age (P < 0.05) and increased maternal education (P < 0.05). The birth prevalence of OFC in Shanxi Province of northern China is among the highest worldwide. Further studies are required to define the factors associated with excess risk of clefts.     

Association of low‐frequency genetic variants in regulatory regions with nonsyndromic orofacial clefts

Genome‐wide scans have shown that common risk alleles for orofacial clefts (OFC) tend to be located in noncoding regulatory elements and cumulatively explain only part of the heritability of OFCs. Low‐frequency variants may account for some of the “missing” heritability. Therefore, we scanned low‐frequency variants located within putative craniofacial enhancers to identify novel OFC risk variants and implicate new regulatory elements in OFC pathogenesis. Analyses were performed in a multiethnic sample of 1,995 cases of cleft lip with or without cleft palate (CL/P), 221 cases with cleft palate (CP) only, and 1,576 unaffected controls. One hundred and nineteen putative craniofacial enhancers identified from ChIP‐Seq studies in craniofacial tissues or cell lines contained multiple low‐frequency (0.01–1%) variants, which we genotyped in participants using a custom Illumina panel. Two complementary statistical approaches, sequence kernel association test and combined multivariate and collapsing, were used to test association of the aggregated low‐frequency variants across each enhancer region with CL/P and CP. We discovered a significant association between CP and a branchial arch enhancer near FOXP1 (mm60; p‐value = .0002). Additionally, we observed a suggestive association between CL/P and a forebrain enhancer near FOXE1 (hs1717; p‐value = .001). These findings suggest that low‐frequency variants in craniofacial enhancer regions contribute to the complex etiology of nonsyndromic OFCs.     

Associated anomalies in multi-malformed infants with cleft lip and palate: An epidemiologic study of nearly 6 million births in 23 EUROCAT registries

We studied 5,449 cases of cleft lip (CL) with or without cleft palate (CL/P) identified between 1980 and 2000 from the EUROCAT network of 23 registers (nearly 6 million births) in 14 European countries. We investigated specific types of defects associated with clefts. Among CL/P cases (prevalence = 9.1 per 10,000), 1,996 (36.6%) affected only the lip (CL) and 3,453 (63.4%) involved CL and palate (CLP). A total of 3,860 CL/P cases (70.8%) occurred as isolated anomalies and 1,589 (29.2%) were associated with other defects such as multiple congenital anomalies of unknown origin (970), chromosomal (455) and recognized syndromes (164). Associated malformations were more frequent in infants who had CLP (34.0%) than in infants with CL only (20.8%). Among multi-malformed infants, 2 unrelated anomalies were found in 351 cases, 3 in 242 cases, and 4 or more in 377 cases. Among 5,449 CL/P cases, 4,719 were live births (LB) (86.6%), 203 stillbirths (SB) (3.7%), while 508 (9.3%) were terminations of pregnancy (ToP). CL/P occurred significantly more frequently in males (M/F = 1.70), especially among total isolated cases (M/F = 1.87) and CLP isolated cases (M/F = 1.92). The study confirmed that musculoskeletal, cardiovascular, and central nervous system defects are frequently associated with CL/P. An association with reduction anomalies of the brain was found. This association suggests that clinicians should seek to identify structural brain anomalies in these patients with CL/P as the potential functional consequences may be important for rehabilitation and clinical management.     

Associated anomalies among infants with oral clefts at birth and during a 1-year follow-up

Reports of birth defects rates may focus on defects observed in the newborn period or include defects diagnosed at older ages. However, little information is available on the rates of additional anomalies detected after birth or on the ages at which such anomalies are diagnosed. The aims of this work were to describe the initial diagnoses of oral clefts, isolated or associated with other defects, in newborn infants ascertained in hospitals of the ECLAMC network, and diagnostic changes that occurred due to detection of additional defects during a 1-year follow-up period. Seven hundred ten liveborn infants with cleft lip only (CLO), cleft lip with cleft palate (CLP), or cleft palate (CP) were ascertained between 2003 and 2005. Prevalence estimates of isolated and associated (ASO) clefts, diagnoses in infants with associated clefts, and the percentage of isolated clefts that were reclassified as associated were established. Birth prevalence estimates (per 1,000) were as follows: Total: 1.7; CLP: 0.94 (ASO = 23.5%); CP: 0.46 (ASO = 42.3%); CLO: 0.28 (ASO = 7.6%). Initial diagnoses in infants with associated clefts included 38 infants with chromosomal abnormalities, 33 with non-chromosomal syndromes, 16 with malformation sequences, and 98 with multiple anomalies of unknown etiology. Seven percent of newborns initially classified as isolated were later reclassified as associated. Ten infants without associated defects or clinically suspected syndromes were diagnosed as syndromic only through laboratory findings or family history, illustrating the difference between the terms associated versus isolated, which refers to presence or absence of associated anomalies, and syndromic versus non-syndromic, which refers to etiology.     

Associations between laterality of orofacial clefts and medical and academic outcomes

Patients with oral clefts have an increased risk of other malformations, syndromes, and lower academic performance in school. Few studies have investigated if laterality of clefts is associated with medical and academic outcomes. Oral clefts have nonrandom laterality, with left‐sided clefts occurring approximately twice as often as right‐sided clefts. Using a retrospective study design, we examined potential associations of cleft attributes and outcomes in patients with cleft lip with or without cleft palate (CL/P) born in 2003–2010 who were treated at the Seattle Children's Craniofacial Center. The following variables were extracted from medical records: cleft type, medical history, maternal hyperglycemia, other malformations, and the need for academic support at school. We used logistic regression to examine risk of associations with outcomes of interest. Relative to patients with left‐sided clefts, patients with bilateral CL/P were more likely to have a syndrome. Patients with nonsyndromic right‐sided CL/P had a higher risk (OR and 95%CI: 3.5, 1.3–9.5, and 5.5, 1.9–16.0, respectively) of having other malformations and requiring academic support at school, when compared to patients with left‐sided CL/P. Understanding the etiology of oral clefts is complicated, in part because both genetic and environmental factors contribute to the risk of developing a cleft. However, the different outcomes associated with cleft laterality suggest that right‐sided clefts may have a distinct etiology. Using laterality to study cleft subgroups may advance our understanding of the etiology of this common birth defect.

     

Survey of genetic counselors and clinical geneticists regarding recurrence risks for families with nonsyndromic cleft lip with or without cleft palate

Nonsyndromic cleft lip with or without cleft palate (CL/P) is a common congenital malformation affecting about 1/1,000 caucasian infants. Although the familial clustering of CL/P has been studied thoroughly, estimation of recurrence risk for genetic counseling purposes can be difficult. A survey was mailed to 912 board-certified genetic counselors, 542 non-board-certified genetic counselors, and 776 board-certified clinical geneticists to investigate the recurrence risks they would assign to three example families with CL/P. Responses were received from 155 (17%) board-certified genetic counselors, 36 (6.6%) non-board-certified genetic counselors, and 100 (18.5%) board-certified clinical geneticists. No major differences were found in their responses, suggesting that for these three families, geneticists would provide similar estimates of risk, regardless of their amount of experience with oral clefts patients, where they are currently employed, or their board certification status. Am. J. Med. Genet. 79:184–190, 1998. © 1998 Wiley-Liss, Inc.     

Methylenetetrahydrofolate reductase thermolabile variant and oral clefts

Folic acid can prevent neural tube defects; in some cases the mechanism is probably a correction of a metabolic defect caused by thermolabile methylenetetrahydrofolate reductase (MTHFR) found in increased frequency in cases. It is less clear whether folic acid can prevent oral clefts, in part because it is not known whether thermolabile MTHFR is more common in those with oral clefts. This study examined the prevalence of the mutation (677 C→T) that causes thermolabile MTHFR in subjects with oral clefts from a national Irish support group, and an anonymous control group randomly selected from a neonatal screening program covering all births in Ireland. Eighty-three of 848 control subjects were homozygous (TT) thermolabile MTHFR (9.8%). This defect was almost three times as common in the 27 subjects (25.9%) with isolated cleft palate (odds ratio 3.23, 95% confidence interval 1.32 –7.86, P = 0.02) and somewhat more common in the 66 subjects with cleft lip with or without cleft palate (15.2%, odds ratio 1.65, 95% confidence interval 0.81–3.35, P = 0.20). When the two groups with different etiologies were combined, the overall odds ratio was 2.06 (95% confidence interval 1.16–3.66, P = 0.02). In the Irish population homozygosity for the common folate-related polymorphism associated with thermolabile MTHFR is significantly more frequent in those with isolated cleft palate, and could be etiologically important. Am. J. Med. Genet. 86:71–74, 1999. Published 1999 Wiley-Liss, Inc.     

Analysis of genomewide association signals for nonsyndromic cleft lip/palate in a Kenya African Cohort

Nonsyndromic cleft lip with or without cleft palate is a common birth defect with a wide range of prevalence among different populations, apparently highest in Asians and Amerindians and lowest in Africans. Recent genomewide association studies of European-derived and Asian populations have identified six confirmed loci for this phenotype: 1p22.1, 1q32.2 (IRF6), 8q24, 10q25.3, 17q22, and 20q12. However, there have thus far been no studies of these loci in African patients with nonsyndromic cleft lip with or without cleft palate. We carried out association analysis of SNPs in these six candidate chromosomal regions in 128 nonsyndromic cleft lip with or without cleft palate cases and 105 controls from the Rift Valley of Kenya. We observed no apparent association of this phenotype with any of these SNPs, though there was strong statistical power only for 8q24. These results indicate that at least the 8q24 locus does not play a major role in the pathogenesis of nonsyndromic cleft lip with or without cleft palate in east Africa, supporting locus heterogeneity for susceptibility to this phenotype among different major populations of the world.     

唇腭裂相关基因研究进展

唇腭裂是一种常见的先天性畸形,其病因非常复杂,目前倾向认为是由多种基因和环境因素共同作用的结果。常见的引起唇腭裂相关的基因有TGFA,TGFβ3, BCL3, F13A等;环境因素在唇腭裂发生中的遗传修饰作用也很重要,主要的环境激发因素包括致畸因子（如烟草、酒精、糖皮质激素等）、感染和营养缺乏。基于基因打靶技术建立的鼠基因敲除模型很好地模拟了人类疾病的表现型,成为研究唇腭裂的一种强有力手段。     

Expression and association data strongly support JARID2 involvement in nonsyndromic cleft lip with or without cleft palate

Nonsyndromic cleft lip with or without cleft palate (CL/P) affects approximately 1 in 1,000 births. Genetic studies have provided evidence for the role of several genes and candidate loci in clefting; however, conflicting results have frequently been obtained and much have to be done to unravel the complex genetics of CL/P. In the present investigation we have focused on the candidate region in 6p23, a region that have been found linked to CL/P in several investigations, in the attempt to find out the susceptibility gene provisionally named OFC1. Gene expression experiments in mice embryo of positional candidate genes revealed that JARID2 was highly and specifically expressed in epithelial cells in merging palatal shelves. A family‐based linkage disequilibrium study confirmed the pivotal role of JARID2 in orofacial development and strongly supports a role for this gene in CL/P etiology (multiallelic haplotype test P=6×10^?5). Understanding the molecular role of JARID2 within facial development may offer additional information to further unravel the complex genetics of CL/P. Hum Mutat 31:1–7, 2010. © 2010 Wiley‐Liss, Inc.     

Associated anomalies in Pierre Robin sequence

Pierre Robin sequence (PRS) is frequently co-occurring with other non-PRS congenital anomalies. The types and the prevalence of anomalies co-occurring with PRS vary in the reported studies. The aims of this report was to study the types and the prevalence of the anomalies co-occurring with PRS in a well-studied population northeastern France. The types and the prevalence of anomalies co-occurring in cases with PRS were ascertained in all terminations of pregnancy, stillbirths and live births in 387,067 births occurring consecutively during the period 1979–2007 in the area covered by our registry of congenital anomalies which is population-based, 89 cases of PRS were registered during the study period with a prevalence of 2.29 per 10,000 births, 69.7% of the cases had associated non-PRS anomalies. Chromosomal abnormalities were present in 10 (11.2%) cases including three 22 q11.2 deletion. Non-chromosomal recognizable conditions were diagnosed in 27 cases (30.3%) including 10 Stickler syndrome, 8 Treacher Collins syndrome, 3 cases with short stature and 6 other syndromes. Multiple congenital anomalies (MCA) were present in 25 cases (28.1%). The most frequent MCA were in the ear, face and neck (35 out of 98 anomalies, 35.7%), cardiovascular (18 anomalies, 18.4%), musculoskeletal (11 anomalies, 11.2%), central nervous (7 anomalies, 7.1%), urinary (6 anomalies, 6.1%), and eye (6 anomalies, 6.1%) system. The high prevalence of associated anomalies justifies a thorough screening for other congenital anomalies in cases with PRS.     

Suggestion of linkage of a major locus for nonsyndromic orofacial cleft with F13A and tentative assignment to chromosome 6

A Danish material of 58 pedigrees with nonsyndromic orofacial cleft, selected out of a comprehensive Danish material for suggestiveness of autosomal dominant inheritance, was studied for linkage with 42 non-DNA polymorphic marker systems. Both cleft lip with or without cleft palate (CL(P)) and cleft lip alone (CP) were, for the purpose of linkage analysis, scored as if they were due to an autosomal dominant gene with complete penetrance. The highest lod score was with the blood clotting factor XIIIA (F13A): for males alone z = 3.40 at theta = 0.00, for females alone z = 0.30 at theta = 0.21, and for these together z = 3.66 at at theta = 0.00 for males and 0.26 for females. Since F13A is known to be located distally on chromosome 6, we tentatively assign a major locus for orofacial cleft to this region. Since both CL(P) and CP pedigrees contribute to the positive score, the question arises whether this locus carries two cleft alleles.     

Taking it to the max: the genetic and developmental mechanisms coordinating midfacial morphogenesis and dysmorphology

The rapid proliferative expansion and complex morphogenetic events that coordinate the development of the face underpin the sensitivity of this structure to genetic and environmental insult and provide an explanation for the high incidence of midfacial malformation. Most notable of these malformations is cleft lip with or without cleft palate (CLP) that, with an incidence of between one in 600 and one in 1000 live births, is the fourth most common congenital disorder in humans. Despite the obvious global impact of the disorder and some recent progress in identifying causative genes for some prominent syndromal forms, our knowledge of the key genetic factors contributing to the more common isolated cases of CLP is still remarkably patchy. The current understanding of the molecular and cellular processes that orchestrate morphogenesis of the midface, with emphasis on events leading to fusion of the lip and primary palate, is detailed in this review. The roles of crucial factors identified from relevant animal model systems, including BMP4 and SHH, and the likely events perturbed by key genes pinpointed in human studies [such as PVRL1, IRF6p63, MID1, MSX1, and PTCH1] are discussed in this light. New candidates for human CLP genes are also proposed.     

Cellular and molecular mechanisms in the development of a cleft lip and/or cleft palate; insights from zebrafish (Danio rerio)

Human cleft lip and/or palate (CLP) are immediately recognizable congenital abnormalities of the face. Lip and palate develop from facial primordia through the coordinated activities of ectodermal epithelium and neural crest cells (NCCs) derived from ectomesenchyme tissue. Subtle changes in the regulatory mechanisms of NCC or ectodermal epithelial cells can result in CLP. Genetic and environmental contributions or a combination of both play a significant role in the progression of CLP. Model organisms provide us with a wealth of information in understanding the pathophysiology and genetic etiology of this complex disease. Small teleost, zebrafish (Danio rerio) is one of the popular model in craniofacial developmental biology. The short generation time and large number of optically transparent, easily manipulated embryos increase the value of zebrafish to identify novel candidate genes and gene regulatory networks underlying craniofacial development. In addition, it is widely used to identify the mechanisms of environmental teratogens and in therapeutic drug screening. Here, we discuss the value of zebrafish as a model to understand epithelial and NCC induced ectomesenchymal cell activities during early palate morphogenesis and robustness of the zebrafish in modern research on identifying the genetic and environmental etiological factors of CLP.     

Additional data on spontaneous abortion and facial cleft malformations

Examination of fetal wastage data for a large collection of CL ± P and CP sibships reported previously (Bear 1978) does not indicate the frequency of recognized abortion to be higher in the sibships of CL + P vs CL index cases, female vs male CL ± P index cases, bilateral vs unilateral CL ± P index cases, female bilateral CL ± P index cases vs male unilateral CL ± P index cases, or male vs female CP index cases. These observations fail to confirm those reported by Dronamraju (Dronamraju et al. 1982, Dronamraju & Bixler 1983a, b), and provide no evidence of a positive relation between degree of liability to facial cleft malformation and fetal mortality.     

C677T variant form at the MTHFR gene and CL/P: A risk factor for mothers?

Maternal folic acid supplementation in early pregnancy has been suggested to play a role in the prevention of nonsyndromic orofacial cleft, i.e., cleft lip with or without cleft palate (CL/P). Moreover, some authors demonstrated association of the C→T mutation (C677T), converting an alanine to a valine residue in 5,10‐methylenetetrahydrofolate reductase (MTHFR) gene, with other congenital anomalies such as neural tube defects (NTDs). Because of MTHFR’s involvement in the metabolism of folate, we investigated 64 CL/P patients and their parents for C677T MTHFR mutation. No linkage disequilibrium was found using the transmission disequilibrium test (TDT). However, a significantly higher mutation frequency was detected in mothers of CL/P patients compared to controls. The odds ratios calculated for mothers having CT or TT genotype, compared to the normal CC genotype, were 2.75 (95% confidence interval 1.30–5.57) and 2.51 (1.00–6.14), respectively. These results support the involvement of the folate pathway in the etiology of CL/P, and indicate an effect of the maternal genotype, rather than influence of the embryo’s genotype. © 2001 Wiley‐Liss, Inc.