PubMed · 14198565
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M L LUCID. 1964. THE INTERLOCKING SLIP KNOT.. https://doi.org/10.1097/00006534-196408000-00015
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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.
Clefts of the lip and/or palate (CL/P) are among the most common birth defects worldwide. The majority are non-syndromic where CL/P occurs in isolation of other phenotypes. Where one or more additional features are involved, clefts are referred to as syndromic. Collectively CL/P has a major clinical impact requiring surgical, dental, orthodontic, speech, hearing and psychological treatments or therapies throughout childhood. The etiology of CL/P is complex and thought to involve both major and minor genetic influences with variable interactions from environmental factors. Using a combination of gene targeting technology and traditional developmental techniques in both mouse and chick, significant progress has been made in the identification of numerous genes and gene pathways critical for craniofacial development. Despite this, it has been a particular source of frustration that mutation screening of specific candidates, association studies and even genome-wide scans have largely failed to reveal the molecular basis of human clefting. Nevertheless, some important findings have recently come from studies involving syndromic forms of the disorder. These include several genes which have now been shown to contribute a major effect on the etiology of CL/P. Furthermore, these genes can also be used to demonstrate a significant overlap between syndromic and non-syndromic CL/P. The study of these syndromic genes and their molecular pathways will provide a useful and informative route with which to gain a better understanding of human craniofacial pathology.
Three Japanese families with Van der Woude syndrome (VWS) were screened for mutations in the interferon regulatory factor 6 gene (IRF6) by sequencing its entire coding region. Two novel missense mutations, R45Q in exon 3 and P396S in exon 9, were identified in families 1 and 2, respectively. In family 3, no causative base change was found by the sequencing analysis, but a deletion involving exons 4-9 was suggested by multiplex PCR analysis. To confirm the deletion and to determine its 5'- and 3'-boundaries, we amplified a DNA fragment containing a heterozygous polymorphic site in exon 2 by using a 5'-upstream forward PCR primer and eight different reverse primers located 3'-downstream of exon 2. The amplified product was subjected to nested PCR to generate a DNA fragment containing the polymorphic site. When a reverse primer located within the deletion was used for the first PCR amplification, only the nondeletion allele was detected after the second PCR. Repeated analyses with eight different reverse primers allowed us to map the boundaries of the deletion, and subsequently a heterozygous 17,162-bp deletion involving exons 4-9 was identified. Since IRF6 mutations in a significant portion of VWS patients remain undetected by conventional sequencing analysis, it may be important to search for a large deletion in those patients. Our simple methods to identify deletions and to determine the boundaries of a deletion would facilitate the identification of such patients.