Hannele Koillinen

Dominant Mutations in GRHL3 Cause Van der Woude Syndrome and Disrupt Oral Periderm Development

Mutations in interferon regulatory factor 6 (IRF6) account for ∼70% of cases of Van der Woude syndrome (VWS), the most common syndromic form of cleft lip and palate. In 8 of 45 VWS-affected families lacking a mutation in IRF6, we found coding mutations in grainyhead-like 3 (GRHL3). According to a zebrafish-based assay, the disease-associated GRHL3 mutations abrogated periderm development and were consistent with a dominant-negative effect, in contrast to haploinsufficiency seen in most VWS cases caused by IRF6 mutations. In mouse, all embryos lacking Grhl3 exhibited abnormal oral periderm and 17% developed a cleft palate. Analysis of the oral phenotype of double heterozygote (Irf6(+/-);Grhl3(+/-)) murine embryos failed to detect epistasis between the two genes, suggesting that they function in separate but convergent pathways during palatogenesis. Taken together, our data demonstrated that mutations in two genes, IRF6 and GRHL3, can lead to nearly identical phenotypes of orofacial cleft. They supported the hypotheses that both genes are essential for the presence of a functional oral periderm and that failure of this process contributes to VWS.

Collagen XI sequence variations in nonsyndromic cleft palate, Robin sequence and micrognathia

Cleft palate is a common birth defect, but its etiopathogenesis is mostly unknown. Several studies have shown that cleft palate has a strong genetic component. Robin sequence consists of three of the following four findings: micrognathia, glossoptosis, obstructive apnea, and cleft palate. While cleft palate is mainly nonsyndromic, about 80 percent of Robin sequence cases are associated with syndromes. Mutations in genes coding for cartilage collagens II and XI, COL2A1, COL11A1 and COL11A2, have been shown to cause chondrodysplasias that are commonly associated with Robin sequence, micrognathia or cleft palate. We therefore analyzed a cohort of 24 patients with nonsyndromic Robin sequence, 17 with nonsyndromic cleft palate and 21 with nonsyndromic micrognathia for mutations in COL11A2. A total of 23 Robin sequence patients were also analyzed for mutations in COL2A1 and COL11A1. We detected two disease-associated mutations in patients with Robin sequence, an Arg to stop codon mutation in COL11A2 and a splicing mutation in COL11A1. Two putatively disease-associated sequence variations were found in COL11A1 in Robin sequence patients, one in COL11A2 in a patient with micrognathia and one in COL2A1 in two patients with Robin sequence. The results showed that sequence variations in these genes can play a role in the etiology of Robin sequence, cleft palate and micrognathia but are not common causes of these phenotypes.

Mapping of the second locus for the Van der Woude syndrome to chromosome 1p34

The Van der Woude syndrome (VWS) is a dominantly inherited developmental disorder characterized by pits and/or sinuses of the lower lip, cleft lip and/or cleft palate. It is the most common cleft syndrome. VWS has shown remarkable genetic homogeneity in all populations, and so far, all families reported have been linked to 1q32-q41. A large Finnish pedigree with VWS was recently found to be unlinked to 1q32-q41. In order to map the disease locus in this family, a genome wide linkage scan was performed. A maximum lod score of 3.18 was obtained with the marker D1S2797, thus assigning the disease locus to chromosomal region 1p34. By analyses of meiotic recombinants an ∼30 cM region of shared haplotypes was identified. The results confirm the heterogeneity of the VWS syndrome, and they place the second disease locus in 1p34. This finding has a special interest because the phenotype in VWS closely resembles the phenotype in non-syndromic forms of cleft lip and palate.

A genome-wide scan of non-syndromic cleft palate only (CPO) in Finnish multiplex families

Oral clefts are the most common congenital malformations worldwide. Cleft palate can be non-syndromic (MIM 119540) or it can appear as a part of a syndrome or recurrence pattern. Non-syndromic cleft palate and non-syndromic cleft lip with or without cleft palate (CL/P) are considered to be separate entities, on the basis of different embryonic timing and epidemiology. However, in some syndromes, both of these cleft types segregate in the same pedigree, suggesting that they might share a common genetic background. Oral clefts manifest in over 300 different syndromes, and in some of these syndromes the gene defect is already known (Online Mendelian Inheritance in Man database 2004, http://www.ncbi.nlm.nih.gov/Omim/). Identified mutations in cleft syndromes have shown that functionally and structurally very distinct types of genes have an effect on palatogenesis. Recently, a mutation in interferon regulatory factor 6 (IFR6) was found to cause van der Woude syndrome (VWS) (MIM 119300),1 which is one of the most common cleft syndromes. Mutations in very different type of genes can lead to cleft palate in mice. These genes encode growth factors, receptors, transcription regulators, and enzymes for signalling molecule synthesis. Cleft palate, in addition to other congenital malformations, is found in ∼70 knock out mice strains (The Transgenic/Targeted Mutation Database, http://tbase.jax.org/). Other anomalies occur frequently, and therefore no exact model for non-syndromic cleft palate exists. Usually the penetrance is not complete, but Msx-1 knock outs result in 100% cleft palate.2 It has been suggested that, in humans, ∼50% of cases of cleft palate are non-syndromic.3 The etiology and pathogenesis of non-syndromic cleft palate—and also of all other clefts—are poorly understood. Extrinsic factors, such as maternal smoking4 with a particular allele in TGFα locus,5–7 maternal alcohol consumption,8,9 maternal intake of drugs during the first trimester,10 and …

Novel and de novo mutations of the IRF6 gene detected in patients with Van der Woude or popliteal pterygium syndrome

The interferon regulatory factor 6 gene (IRF6) has been identified as the major Van der Woude (VWS) syndrome and popliteal pterygium (PPS) syndrome gene with mutations in the majority of the kindreds. We have studied altogether 17 kindreds from Sweden, Finland, Norway, Thailand and Singapore, and report here 10 mutations, six of them previously unseen. In two kindreds, we could document de novo mutations, both of them changing a codon for a glutamine residue to a stop. No mutation could be detected in the four VWS kindreds from Finland, suggesting a founder effect for a mutation in an atypical noncoding position. Our findings demonstrate that several distinct mutations occur in the Swedish population, and confirm the general notion of a broad spectrum of IRF6 mutations underlying the VWS/PPS phenotypes.

Microdeletions of ELP4 Are Associated with Language Impairment, Autism Spectrum Disorder, and Mental Retardation.

Copy‐number variations (CNVs) are important in the aetiology of neurodevelopmental disorders and show broad phenotypic manifestations. We compared the presence of small CNVs disrupting the ELP4‐PAX6 locus in 4,092 UK individuals with a range of neurodevelopmental conditions, clinically referred for array comparative genomic hybridization, with WTCCC controls (n = 4,783). The phenotypic analysis was then extended using the DECIPHER database. We followed up association using an autism patient cohort (n = 3,143) compared with six additional control groups (n = 6,469). In the clinical discovery series, we identified eight cases with ELP4 deletions, and one with a partial duplication of ELP4 and PAX6. These cases were referred for neurological phenotypes including language impairment, developmental delay, autism, and epilepsy. Six further cases with a primary diagnosis of autism spectrum disorder (ASD) and similar secondary phenotypes were identified with ELP4 deletions, as well as another six (out of nine) with neurodevelopmental phenotypes from DECIPHER. CNVs at ELP4 were only present in 1/11,252 controls. We found a significant excess of CNVs in discovery cases compared with controls, P = 7.5 × 10−3, as well as for autism, P = 2.7 × 10−3. Our results suggest that ELP4 deletions are highly likely to be pathogenic, predisposing to a range of neurodevelopmental phenotypes from ASD to language impairment and epilepsy.

Association and Mutation Analyses of the IRF6 Gene in Families With Nonsyndromic and Syndromic Cleft Lip and/or Cleft Palate

Objectives (1) To detect interferon regulatory factor 6 gene (IRF6) mutations in newly recruited Van der Woude syndrome (VWS) and popliteal pterygium syndrome (PPS) families. (2) To test for association, in nonsyndromic cleft lip and/or cleft palate (NSCL/P) and in VWS/PPS families, the single nucleotide polymorphism (SNP) rs642961, from the IRF6 enhancer AP-2α region, alone or as haplotype with rs2235371, a coding SNP (Val274Ile). Design IRF6 mutation screening was performed by direct sequencing and genotyping of rs642961 and rs2235371 by TaqMan technology. Patients Seventy-one Swedish NSCL/P families, 24 Finnish cleft palate (CP) families, and 24 VWS/PPS families (seven newly recruited) were studied. Results Allelic and genotypic frequencies in each phenotype were compared to those of the controls, and no significant difference could be observed. IRF6 gene mutation was detected in six of the seven new VWS/PPS families. Association analysis of the entire VWS/PPS sample set revealed the A allele from rs642961 to be a risk allele. Significant association was detected in the Swedish CP subset of our NSCL/P collection where the G-C haplotype for rs642961-rs2235371 were at risk (P= .013). Conclusions Our results do not support the previously reported association between the A allele of rs642961 and the NSCL phenotype. However, in the VWS/PPS families, the A allele was a risk allele and was, in a large majority (>80%), transmitted on the same chromosome as the IRF6 mutation.

Genitopatellar syndrome in an adolescent female with severe osteoporosis and endocrine abnormalities.

Genitopatellar syndrome (GPS) is a rare disorder with characteristic craniofacial features, congenital flexion contractures of the lower limbs, absent or abnormal patellae, urogenital anomalies, and severe psychomotor retardation. Twelve patients with ages from 15 days to 12 years and two affected fetuses have been reported. We describe a 17‐year‐old female with a phenotype consistent with GPS. Being the oldest reported patient, she is the first one showing severe symptomatic osteoporosis and endocrine abnormalities including primary hypothyroidism and delayed puberty. We suggest that these novel findings are also manifestations of GPS.

Linkage and linkage disequilibrium searched for between non-syndromic cleft palate and four candidate loci

Cleft palate (CP) is one of the most common congenital malformations. It can occur as part of a recognisable syndrome, associated with other malformations or, most commonly, be non-syndromic (CPO) (MIM 119540). The birth prevalence of CPO varies between and among populations but it is seen world wide. The highest incidence has been found in Finland, 1.01 per 1000 livebirths.1 Within Finland, there are regional differences in birth prevalence; the Oulu region (in northern central Finland) and central western Finland are over-represented, with up to twice the incidence compared to the average.1 Differences are even more striking when analysing the birth places of the grandparents of probands.1 The gene defects or susceptibility genes for clefts remain largely unknown and the basic mechanism causing the failure of the secondary palate to close is still poorly understood. Extrinsic factors like advanced paternal age, maternal smoking, and overall intake of medicines during the first trimester have been suggested to increase the risk of CPO.2 Although some pedigrees have shown autosomal dominant and X linked recessive inheritance, the risk of recurrence for relatives in large series of cases differs greatly from expected values calculated on the basis of a simple Mendelian mode of inheritance. Targeted mutations in mice have shown that malfunction of very different types of genes can lead to cleft palate, msx1 and tgfb3 among them.3–5 In humans, defects in genes encoding collagens,6 a fibroblast growth factor receptor,7 a sulphate transporter,8,9 a nucleolar protein,10 and a thyroid transcription factor11 have appeared to be associated with syndromes where cleft palate can be involved. For non-syndromic cleft palate, neither mutations nor linkage to a specific chromosomal region has yet been established. However, linkage disequilibrium was suggested in two studies between MSX1 and …

Genomic Strategy Identifies a Missense Mutation in WD-Repeat Domain 65 (WDR65) in an Individual With Van der Woude Syndrome

Genetic variation in the transcription factor interferon regulatory factor 6 (IRF6) causes and contributes risk for oral clefting disorders. We hypothesized that genes regulated by IRF6 are also involved in oral clefting disorders. We used five criteria to identify potential IRF6 target genes; differential gene expression in skin taken from wild‐type and Irf6‐deficient murine embryos, localization to the Van der Woude syndrome 2 (VWS2) locus at 1p36‐1p32, overlapping expression with Irf6, presence of a conserved predicted‐binding site in the promoter region, and a mutant murine phenotype that was similar to the Irf6 mutant mouse. Previously, we observed altered expression for 573 genes; 13 were located in the murine region syntenic to the VWS2 locus. Two of these genes, Wdr65 and Stratifin, met 4 of 5 criteria. Wdr65 was a novel gene that encoded a predicted protein of 1,250 amino acids with two WD domains. As potential targets for Irf6 regulation, we hypothesized that disease‐causing mutations will be found in WDR65 and Stratifin in individuals with VWS or VWS‐like syndromes. We identified a potentially etiologic missense mutation in WDR65 in a person with VWS who does not have an exonic mutation in IRF6. The expression and mutation data were consistent with the hypothesis that WDR65 was a novel gene involved in oral clefting.