染色体基因位点与非综合征性唇腭裂致病机制的关系

非综合征性唇腭裂是人类最常见的先天性畸形之一,是一种多基因多因素的遗传疾病.近二十年来,学者们先后在多条染色体上发现了与非综合征性唇腭裂有关的基因位点.本文就染色体基因位点与非综合征性唇腭裂致病机制的关系作一综述.     

唇腭裂易感基因的研究进展

唇腭裂是一种常见的先天畸形,病因复杂,目前倾向认为是由多种基因和环境因素共同作用的结果。该文就各染色体上唇腭裂相关易感基因位点的最新研究进行综述。     

干扰素调节因子-6基因多态性与非综合征型唇腭裂的相关性研究

20世纪80年代后期以来,学者们陆续报道了10～20个与非综合征型唇腭裂有关的易感基因和位点,其中干扰素调节因子-6（IRF-6）基因是迄今发现的最有价值的与非综合征型唇腭裂发病相关的基因之一。本文就IRF-6基因的结构和功能、IRF-6基因的多态性及其与非综合征型唇腭裂的相关性研究作一综述。     

中国西部人群IRF6基因SNPs与非综合征型唇腭裂相关性的研究

目的:探讨干扰素调节因子6 (IRF6) 基因rs2013162 和 rs2235375位点单核苷酸多态性(SNPs)与非综合征型唇腭裂的相关性.方法:收集病例组非综合征型唇腭裂患儿332 例,患者父亲243 例,患者母亲289 例,完整的核心家庭206个.对照组收集正常新生儿174 例.采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)方法检测IRF6基因这2 个多态位点基因型,进行病例对照和传递不平衡(TDT)分析.结果:在中国西部人群中,与正常对照组比较,唇腭裂组rs2235375位点的基因型和等位基因的频率存在统计学差异(均P<0.01).运用传递不平衡研究发现IRF6基因rs2235375位点的G等位基因在唇腭裂患者中存在过传递(P<0.01).有5 种单倍型组合显示有传递不平衡.结论:在中国西部人群中IRF6基因多态性与非综合征型唇腭裂的发生存在强的相关性.     

中国西部人群IRF6基因V274I位点SNP与非综合征型唇腭裂相关性的研究

目的:探讨干扰素调节因子6(IRF6)基因V274I位点单核苷酸多态性(SNP)与非综合征型唇腭裂的相关性.方法:收集非综合征型唇腭裂患儿332例,患者父亲243例,患者母亲289例,核心家庭224个,对照组正常新生儿174例.采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)方法检测IRF6基因V274I多态位点基因型,进行病例对照和传递不平衡(TDT)研究.结果:在中国西部人群中,与正常对照组比较,单纯唇裂和唇腭裂组V274I位点SNP的GG基因型和G等位基因的频率存在显著性差异(P=0.000),而在单纯腭裂组比较没有显著性差异(P=0.699).运用传递不平衡研究发现IRF6基因V274I多态性突变的G等位基因在唇裂和唇腭裂患者中存在过传递(P=0.000).结论:在中国西部人群中IRF6基因V274I SNP位点G等位基因与非综合征型唇腭裂存在强的相关性,而与单纯腭裂没有相关性.     

TBX22基因变异与国人部分人群唇腭裂发病的关系

目的:在中国唇腭裂患者中,对TBX22基因进行检测,研究TBX22基因变异或者多态性与部分中国人群唇腭裂的关系。方法:采用基因测序的方法,在100例唇腭裂患者中进行TBX22基因测序,对得到的变异位点,在正常人中进行验证,并对结果进行生物信息学分析。结果:共发现5个TBX22基因变异位点:876G>A(D292N),72C>T(L24L)和其他3个内含子区域的单核苷酸多态性位点。结论:首次在中国人群唇腭裂患者中进行TBX22基因全部外显子区域及附近序列的测序,得出了中国唇腭裂患者TBX22基因的变异情况。     

山西人群MTHFR基因rs1801133位点多态性与非综合征性唇腭裂的关联性研究

目的:研究亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因rs1801133位点多态性与非综合征性唇腭裂(NSCL/P)的关系。方法:采用聚合酶链反应-限制性片段长度多态性方法,检测334例非综合征性唇腭裂患者和314例正常对照组的MTHFR基因rs1801133位点的多态性。结果:MTHFR基因rs1801133位点基因型频率分布符合Hardy-Weinberg平衡;MTHFR基因rs1801133位点基因型及等位基因的分布在NSCL/P组与对照组之间均无统计学意义(P>0.05)。结论:MTHFR基因rs1801133位点多态性与山西人群非综合征性唇腭裂的发生无关。     

TCN2基因与非综合征性唇腭裂的关系

目的研究叶酸代谢相关基因TCN2与中国人群中非综合征性唇腭裂的关系。方法通过聚合酶链反应-限制性片段长度多态性,在108例非综合征性唇腭裂患者和184名正常对照个体中,对TCN2基因2个单核苷酸多态性（SNP）（rs10418和rs1801198）进行检测。利用拟合优度卡方检验,分析基因型分布频率是否符合Hardy-Weinberg平衡定律;应用UNPHASED软件包分析单个单核苷酸多态性位点以及两个位点单倍型与非综合征性唇腭裂的相关性。结果 2个SNP位点基因型频率分布均符合Hardy-Weinberg平衡;等位基因分布和单倍型组合在非综合征性唇腭裂患者与对照组之间无显著性差异;rs10418 TT基因型能增加非综合征性唇腭裂患病风险。结论 TCN2基因rs10418 TT基因型是非综合征性唇腭裂的危险因素。     

干扰素调节因子6基因多态性与非综合征型唇腭裂的相关性研究

目的探讨干扰素调节因子6（IRF6）基因rs642961和rs4844880位点单核苷酸多态性与非综合征型唇腭裂的相关性。方法收集宁夏地区非综合征型唇腭裂患者186例,采用聚合酶链反应-限制性片段长度多态性（PCRRFLP）方法检测IRF6基因多态位点rs642961和rs4844880基因型,进行病例对照分析、传递不平衡检验（TDT）。结果与正常对照组比较,唇裂组和唇腭裂组rs642961和rs4844880位点的AA基因型和A等位基因的频率存在统计学差异（P<0.05）,腭裂组均没有意义（P=0.15, P=0.967）;TDT研究发现IRF6基因rs642961位点的A等位基因和rs4844880位点的A等位基因在唇裂和唇腭裂患者中存在过传递（P<0.05）;2个位点在腭裂组均没有统计学意义（P=0.91,P=0.95）。结论IRF6基因多态性与非综合征型唇腭裂存在较强的相关性。     

THADA基因多态性与非综合征性唇腭裂的相关性研究

目的:探讨中国北方人群甲状腺腺瘤相关基因(THADA) rs7590268、rs13035011和rs6729902位点单核苷酸多态性(SNPs)与非综合征性唇腭裂(NSCL/P)的相关性。方法:应用聚合酶链式反应-连接酶检测反应(PCR-LDR)检测方法,在335例NSCL/P患者和525例健康体检者中,对THADA基因的rs7590268、rs13035011和rs6729902位点进行检测。结果:rs7590268和rs6729902多态性位点等位基因频率在唇裂组与对照组间的分布差异有统计学意义(P＜0.05),rs13035011位点基因型及等位基因频率在病例组和对照组间的分布差异无统计学意义。结论:THADA基因的rs7590268和rs6729902位点单核苷酸多态性可能与中国北方人群非综合征性唇腭裂的发生相关。     

Investigation of MYH14 as a candidate gene in cleft lip with or without cleft palate

Clefts of the orofacial region are among the most common facial defects and are caused by abnormal facial development during gestation. Cleft lip with or without cleft palate (CL/P) is a birth defect with a complex etiology resulting from a mixture of genetic and environmental factors. In the present study we considered myosin 14 ( MYH14 ) as a candidate gene for CL/P. This gene codes for the heavy chain of non-muscle myosin IIC (NMMHC-IIC), maps in the OFC3 region, and shares significant homology with myosin 9, a gene that our group has recently seen to be involved in CL/P. A linkage disequilibrium investigation was conducted with six single nucleotide polymorphisms in MYH14 and a sample of 239 CL/P nonsyndromic patients and their parents. Our family-based investigation provided no evidence of association between MYH14 and CL/P alleles. These data do not support the involvement of MYH14 in CL/P among the Italian population.     

Linkage analysis between BCL3 and nearby genes on 19q13.2 and non-syndromic cleft lip with or without cleft palate in multigenerational Japanese families

OBJECTIVE: To investigate the linkage between candidate genes on chromosome 19 and cleft lip with or without cleft palate in Japanese using a parametric method. MATERIALS AND METHODS: After informed consent was obtained, blood samples were drawn from 90 individuals in 14 families, 30 of whom were affected, and genomic DNAs were extracted. PCR-amplified products using four microsatellite markers, D19S178, BCL3, APOC2[007/008] and APOC2[AC1/AC2] located in 19q13.2, were separated by 8% polyacrylamide gel electrophoresis. Linkage analysis was carried out using the MLINK and LINKMAP programs, and logarithm of odds (LOD) scores were calculated for each family. RESULTS: Before undertaking linkage analysis, we analyzed 74 healthy Japanese subjects and found racial differences in that the observed number of alleles and their heterozygosity were lower in Japanese than in Caucasians, and that both populations tended to show a different allele distribution. In 14 families, two-point maximum LOD score (Zmax) for BCL3 was 0.341 and multi-point Zmax was less than -2 excluding linkage. But in 9 families with left and bilateral CL/P, two-point Zmax for APOC2[AC1/AC2] was 1.701 and multi-point Zmax at APOC2 locus was 1.909. CONCLUSION: The LOD score was relatively high but provided no evidence of linkage for CL/P to BCL3 and nearby genes in Japanese subjects.     

Is alveolar cleft reconstruction still controversial? (Review of literature)

Cleft lip and palate (CL/P) is a frequent congenital malformation that manifests in several varieties including unilateral or bilateral and complete or incomplete. Alveolar cleft reconstruction remains controversial with regard to timing, graft materials, surgical techniques, and methods of evaluation. Many studies have been conducted addressing these points to develop an acceptable universal protocol for managing CL/P. The primary goal of alveolar cleft reconstruction in CL/P patients is to provide a bony bridge at the cleft site that allows maxillary arch continuity, oronasal fistula repair, eruption of the permanent dentition into the newly formed bone, enhances nasal symmetry through providing alar base support, orthodontic movement and placement of osseointegrated implants when indicated. Other goals include improving speech, improvement of periodontal conditions, establishing better oral hygiene, and limiting growth disturbances. In order to rehabilitate oral function in CL/P patients alveolar bone grafting is necessary. Secondary bone grafting is the most widely accepted method for treating alveolar clefts. Autogenous bone graft is the primary source for reconstructing alveolar cleft defects and is currently the preferred grafting material.     

Cleft lip and cleft palate in Santo Domingo

The purpose of this study was to analyze the occurrence of isolated cleft lip (CL), cleft lip with cleft palate (CL + CP) and isolated cleft palate (CP) and their distribution according to sex and laterality in Santo Domingo, Dominican Republic, located in the Caribbean Archipelago. The sample consisted of 439 hospital records (204 males and 235 females) of patients attending a children's public hospital in Santo Domingo over the period of May 1973 to December 1976. Of all facial clefts, the highest percentage (36.4%) was presented by CL, followed by CP (32.1%) and CL + CP (31.4%). Of all facial clefts, males presented the highest percentage (53.5%). For both sexes, there was an equal number of cases with CL (17.54 %) but more males had CL + CP (0.20 > P0.10) and more females presented CP (P < 0.001). The left-sided defects were almost twice as common as the right-sided defects. The ratio of unilateral clefts-to-bilateral clefts was 5.4:1.     

Clinical and genetic study on 356 Brazilian patients with a distinct phenotype of cleft lip and palate without alveolar ridge involvement

Oral clefts include cleft lip (CL), cleft lip with cleft palate (CLP) and cleft palate (CP), with wide variations in clinical presentation and degree of severity. We described a sample of individuals with CL and CP without alveolar arch involvement (CL + CP) to verify if the characteristics of this group are distinct from those with CL with or without CP (CL/P) described in literature. The sample was composed of 356 patients with CL + CP, registered at HRCA-USP, Bauru-SP-Brazil. The following characteristics were investigated: sex ratio, parental age at the time of conception, parental consanguinity, familial recurrence, laterality of the cleft and associated anomalies. A subgroup of 30 individuals with microforms of CL and CP were taken from the sample and compared with the remaining cases. Statistical differences were found between this CL + CP sample and the literature data for groups with CL/P regarding laterality, sex ratio, consanguinity, familial recurrence, and the presence of associated anomalies. The microform sample showed a statistical difference in paternal age. In most evaluated aspects, this sample presents similar characteristics to the consulted literature data for CL/P; as do the group of microform cleft cases when compared with the remaining CL + CP sample in this study. Microforms of cleft can represent a target group for investigation into the embryogenetic mechanisms of oral clefts and their phenotypic variability.     

New evidence for the role of cystathionine beta-synthase in non-syndromic cleft lip with or without cleft palate

Orofacial clefts have a multifactorial aetiology encompassing both genetic and environmental components. While there is wide agreement on the importance of both genetic and nutritional factors, genetic influence in particular has not been well defined. As genetic variants in folate and homocysteine metabolism have been reported to influence the risk of orofacial clefts, an Italian cleft lip with or without cleft palate (CL/P) data set was enrolled for an analysis based on family association to test betaine-homocysteine methyltransferase (BHMT and BHMT2) and cystathionine beta-synthase (CBS) variants. No significant level of association was found between BHMT and BHMT2 variants, while evidence of an allelic association with CL/P was found for the single nucleotide polymorphism rs4920037, mapping at the CBS gene. A log-linear approach indicated that the best genetic model takes into account both mother and child genotypes. This suggests that human orofacial development is influenced by CBS genotypes that possibly operate through intergenerational fetal-maternal interaction.     

Undetected anomalies in foetuses with a prenatal diagnosis of isolated cleft

The aim of this study was to determine the rate of undetected additional anomalies following a prenatal diagnosis of isolated oral cleft. Data of all infants with a prenatal diagnosis of isolated oral cleft born between 2000 and 2015 were studied retrospectively. Additional anomalies detected after birth were categorized as minor or major and included structural and chromosomal anomalies. Isolated clefts of the lip (CL), lip and alveolus (CLA) and lip, alveolus, and palate (CLAP) were diagnosed prenatally in 176 live-born infants. The type of cleft was more extensive after birth in 34/176 (19.3%) and less extensive in 16/176 (9.1%) newborns. Additional anomalies were diagnosed in 24 infants (13.6%), of which 12 (6.8%) were categorized as major. The latter included two submicroscopic chromosome anomalies and two gene mutations. Postnatal additional anomalies occurred more frequently in CLA and CLAP than in CL, and more in bilateral than in unilateral clefts. Major anomalies are still found in infants with a prenatal diagnosis of an isolated oral cleft. The prevalence of additional anomalies seems to be related to the type and bilaterality of the cleft, and this should be considered during prenatal counselling.     

Candidate genes for nonsyndromic cleft lip and palate

The confirmation of supposed genes causing susceptibility to nonsyndromic cleft lip with or without a cleft palate (CL/P) and cleft palate alone (CP) would help to understand the molecular development of the lip, the palate and the jaw, and to predict more accurately the risk of recurrence of such defects. The purpose of this article is to present a brief review of the current state of knowledge regarding the search for genes responsible for the occurrence of CL/P and CP. After ten years of research, approximately twenty candidate genes have already been suggested for CL/P and CP. Some genes or chromosomal regions seem to be frequently associated with these defects and a specific nomenclature (orofacial cleft genes--OFC) has been suggested. Everything indicates that it will still take many years of research before the genes responsible for CL/P and CP are confirmed. These efforts are justified, however, because of the possibility of being able to predict more accurately the risk of such defects occurring.