Non-random distribution of deleterious mutations in the DNA and protein-binding domains of IRF6 are associated with Van Der Woude syndrome.

BACKGROUND: The development of the face occurs during the early days of intrauterine life by the formation of facial processes from the first Pharyngeal arch. Derangement in these well-organized fusion events results in Orofacial clefts (OFC). Van der Woude syndrome (VWS) is one of the most common causes of syndromic cleft lip and/or palate accounting for 2% of all cases. Mutations in the IRF6 gene account for 70% of cases with the majority of these mutations located in the DNA-binding (exon 3, 4) or protein-binding domains (exon 7-9). The current study was designed to update the list of IRF6 variants reported for VWS by compiling all the published mutations from 2013 to date as well as including the previously unreported VWS cases from Africa and Puerto Rico. METHODS: We used PubMed with the search terms; "Van der Woude syndrome," "Popliteal pterygium syndrome," "IRF6," and "Orofacial cleft" to identify eligible studies. We compiled the CADD score for all the mutations to determine the percentage of deleterious variants. RESULTS: Twenty-one new mutations were identified from nine papers. The majority of these mutations were in exon 4. Mutations in exon 3 and 4 had CADD scores between 20 and 30 and mutations in exon 7-9 had CADD scores between 30 and 40. The presence of higher CADD scores in the protein-binding domain (exon 7-9) further confirms the crucial role played by this domain in the function of IRF6. In the new cases, we identified five IRF6 mutations, three novel missense mutations (p.Phe36Tyr, p.Lys109Thr, and p.Gln438Leu), and two previously reported nonsense mutations (p.Ser424*and p.Arg250*). CONCLUSION: Mutations in the protein and DNA-binding domains of IRF6 ranked among the top 0.1% and 1% most deleterious genetic mutations, respectively. Overall, these findings expand the range of VWS mutations and are important for diagnostic and counseling purposes.

The Role of Environmental Factors in the Etiology of Nonsyndromic Orofacial Clefts.

BACKGROUND: Nonsyndromic orofacial clefts (NSOFCs) represent the most common congenital anomalies in the head and neck region. Multiple factors contribute to the occurrence of this anomaly. The etiology of NSOFCs in the Ethiopian population has not been investigated prior to this study. AIMS OF THE STUDY: To assess the role of maternal environmental factors in the occurrence of NSOFCs in the Ethiopian Population. METHODS: The authors used unmatched case control study design and evaluated the role of environmental factors to the occurrence of NSOFCs in the Ethiopian population. The participants were recruited from the same institution (Yekatit 12 Hospital Medical College). The authors studied 760 mothers (359 mothers of children born with NSOFCs and 401 mothers of children born without any congenital anomalies). Univariate and multivariate logistic regression analyses were used to calculate relative risk by odds ratio and 95% confidence interval. RESULTS: Mothers who gave history of bronchial asthma and mothers who were admitted for threatened abortion had a higher risk of delivering a child with NSOFCS P value=0.013; AOR=0.194, 95% CI [0.053-0.712], P value <0.001; AOR= 0.179, 95% CI [0.091-0.352] respectively. Higher number of children with NSOFCs were born to mothers who were exposed to diagnostic X-ray investigation during early pregnancy than those who were not exposed P value 0.048; AOR=0.375, 95% CI [0.142-0.990]. CONCLUSION: Maternal exposure to diagnostic x-ray, maternal chronic illness like bronchial asthma and threatened abortion were found to be associated with the occurrence of NSOFCS in the studied population.

Oral Health-Related Quality of Life of Children Born With Orofacial Clefts in Ethiopia and Their Parents.

OBJECTIVE: To assess the oral health-related quality of life (OH-RQoL) using a translated standardized measure in an understudied population of Ethiopian children born with orofacial clefts (OFCs) and their parents. METHODS: Using a descriptive study design, we assessed the OH-RQoL of 41 patients with OFCs between the ages of 8 and 17 years and their parents. Participants received multidisciplinary cleft care from 2008 to 2016. They completed an Amharic translation of the Child Oral Health Impact Profile (COHIP). RESULTS: There was strong internal reliability with the translated COHIP for parents and patients. Parents' COHIP scores ranged from 67 to 186, and patients' scores were 78 to 190. The mean for patients and parents was 155, indicating good OH-RQoL. CONCLUSION: The Amharic translation of the COHIP appears appropriate for use with families in Ethiopia. Both parents and patients reported OH-RQoL at similar levels as other international populations.

The prevalence, penetrance, and expressivity of etiologic IRF6 variants in orofacial clefts patients from sub-Saharan Africa.

BACKGROUND: Orofacial clefts are congenital malformations of the orofacial region, with a global incidence of one per 700 live births. Interferon Regulatory Factor 6 (IRF6) (OMIM:607199) gene has been associated with the etiology of both syndromic and nonsyndromic orofacial clefts. The aim of this study was to show evidence of potentially pathogenic variants in IRF6 in orofacial clefts cohorts from Africa. METHODS: We carried out Sanger Sequencing on DNA from 184 patients with nonsyndromic orofacial clefts and 80 individuals with multiple congenital anomalies that presented with orofacial clefts. We sequenced all the nine exons of IRF6 as well as the 5' and 3' untranslated regions. In our analyses pipeline, we used various bioinformatics tools to detect and describe the potentially etiologic variants. RESULTS: We observed that potentially etiologic exonic and splice site variants were nonrandomly distributed among the nine exons of IRF6, with 92% of these variants occurring in exons 4 and 7. Novel variants were also observed in both nonsyndromic orofacial clefts (p.Glu69Lys, p.Asn185Thr, c.175-2A>C and c.1060+26C>T) and multiple congenital anomalies (p.Gly65Val, p.Lys320Asn and c.379+1G>T) patients. Our data also show evidence of compound heterozygotes that may modify phenotypes that emanate from IRF6 variants. CONCLUSIONS: This study demonstrates that exons 4 and 7 of IRF6 are mutational 'hotspots' in our cohort and that IRF6 mutants-induced orofacial clefts may be prevalent in the Africa population, however, with variable penetrance and expressivity. These observations are relevant for detection of high-risk families as well as genetic counseling. In conclusion, we have shown that there may be a need to combine both molecular and clinical evidence in the grouping of orofacial clefts into syndromic and nonsyndromic forms.

Descriptive Epidemiology of Orofacial Clefts in Ethiopia.

BACKGROUND: The prevalence of birth defects including orofacial clefts (OFC) in Ethiopia is not known and there is no established birth defects registration system. OBJECTIVES: To investigate the prevalence and incidence of OFC in Ethiopia. DESIGN: Retrospective hospital-based descriptive study. METHODS: The authors obtained data from the Smile Train database on Ethiopian patients with OFC who underwent surgical treatment from June 2007 to December 2013 at 31 hospitals distributed throughout the country. Data related to live births in Ethiopia during the mentioned period were obtained from the Federal Ministry of Health database for estimates of the incidence and prevalence rates. RESULTS: The total number of life births during the study period was 18,811,316. During this same period, 18,073 cleft patients approximately ranging from 1 to 75 years old were examined and treated at the hospitals mentioned earlier. The incidence rate estimated from the total number of affected children during the study period (N = 8232) is 0.44/1000 live births. The prevalence rate is 0.20/1000 and this was estimated using the number of total population in 2013 (N = 88,703,914). There is a significant difference in frequency between bilateral clefts of the lip and/or palate (CLP) (26.9%) versus unilateral CLP (73.1%) (P < 0.0001). There is also a significant difference in frequency between bilateral cleft lips only (15.4%) versus unilateral cleft lip only (84.6%), P < 0001. CONCLUSION: It is obvious that the findings in this study cannot be representative of the true picture but provides a previously unavailable national estimate of incidence and prevalence of OFC in Ethiopia. It can also be used as comparison for future community-based studies.

Congenital Palatal Fistula Associated with Submucous Cleft Palate.

UNLABELLED: Although cleft lip and cleft palate are among the most common congenital malformations, the presence of an isolated congenital palatal fistula along with a submucous cleft is very rare. This appears as an oval-shaped, full-thickness fenestration in the palatal midline that does not fully extend anteriorly or posteriorly, accompanied by the findings of a submucous cleft. Because of the uncommon nature of this entity, there is controversy about its etiology, diagnosis, and management. METHODS: Two cases of children with congenital palatal fistulae and a submucous cleft palate are presented who were treated in different settings by different surgeons. Cases are discussed along with a thorough review of the available literature. RESULTS: Patient 1 presented at 4 years of age with "a hole in the palate" since birth and abnormal speech. His palatal fistula and submucous cleft were repaired with a modified von Langenbeck technique in Ethiopia. At a 2-year follow-up, the palate remained closed, but hypernasal speech persisted. Patient 2 was a 1-year-old presenting with failure to thrive and nasal regurgitation, who underwent a Furlow palatoplasty in the United States with good immediate results. She was unfortunately lost to follow-up. CONCLUSIONS: A congenital fenestration of the palate is rare. Reports reveal suboptimal speech at follow-up, despite various types of repair, especially when combined with a submucous cleft. Available literature suggests that repair should not focus on fistula closure only but instead on providing adequate palate length to provide good velopharyngeal function, as in any cleft palate repair.

Foreign Bodies Simulating a Congenital Palatal Fistula and Vascular Anomaly.

Foreign bodies embedded in the palate are uncommon findings and may occasionally mimic oral lesions. In the majority of the cases, foreign body embedment in the palate happens in infants and children who are unable to give history. Physical examination in the oral cavity of this group of patients in order to arrive at a definitive diagnosis is limited. We present two female infants with foreign bodies adherent to the hard palate. The first was ten months old and the second was 11 months old. In both cases the materials removed from the palate were plastic in nature (black or red in color and circular in shape). The first simulated a palatal fistula and the second a vascular anomaly.

Rare functional variants in genome-wide association identified candidate genes for nonsyndromic clefts in the African population.

Nonsyndromic clefts of the lip and palate (NSCLP) are complex genetic traits. Together, they are classified as one of the most common birth defects with a prevalence of 1/700 live births. Genome-wide association studies (GWAS) for nonsyndromic cleft lip with or without cleft palate (NSCL[P]) revealed significant association for common single nucleotide polymorphisms near genes involved in craniofacial development i.e., MAFB, PAX7, VAX1, ARHGAP29 (ABCA4 locus), and IRF6. Sequencing of protein coding regions of the NSCL(P) GWAS candidate genes or adjacent genes suggest a role for rare functional variants. Replication studies in the African population did not observe any significant association with the GWAS candidate genes. On the other hand, the role of rare functional variants in GWAS candidate genes has not been evaluated in the African population. We obtained saliva samples from case triads in Nigeria and Ethiopia for Sanger sequencing of the GWAS candidate genes (MAFB, PAX7, VAX1, ARHGAP29, and IRF6) in order to identify rare functional variants. A total of 220 African samples (140 Nigerians and 80 Ethiopians) were sequenced and we found the following new rare variants- p.His165Asn in the MAFB gene, p.Asp428Asn in the PAX7, a splice-site variant that creates a new donor splice-site in PAX7. We also found three previously reported missense variants p.Gly466Ser in PAX7; p.Leu913Ser and Arg955His in ARHGAP29. No de novo mutations were found. Future genome-wide association and sequencing studies should be conducted using samples from Africa in order to identify new molecular genetic factors that contribute to the etiology of NSCLP.

Novel IRF6 mutations in families with Van Der Woude syndrome and popliteal pterygium syndrome from sub-Saharan Africa.

Orofacial clefts (OFC) are complex genetic traits that are often classified as syndromic or nonsyndromic clefts. Currently, there are over 500 types of syndromic clefts in the Online Mendelian Inheritance in Man (OMIM) database, of which Van der Woude syndrome (VWS) is one of the most common (accounting for 2% of all OFC). Popliteal pterygium syndrome (PPS) is considered to be a more severe form of VWS. Mutations in the IRF6 gene have been reported worldwide to cause VWS and PPS. Here, we report studies of families with VWS and PPS in sub-Saharan Africa. We screened the DNA of eight families with VWS and one family with PPS from Nigeria and Ethiopia by Sanger sequencing of the most commonly affected exons in IRF6 (exons 3, 4, 7, and 9). For the VWS families, we found a novel nonsense variant in exon 4 (p.Lys66X), a novel splice-site variant in exon 4 (p.Pro126Pro), a novel missense variant in exon 4 (p.Phe230Leu), a previously reported splice-site variant in exon 7 that changes the acceptor splice site, and a known missense variant in exon 7 (p.Leu251Pro). A previously known missense variant was found in exon 4 (p.Arg84His) in the PPS family. All the mutations segregate in the families. Our data confirm the presence of IRF6-related VWS and PPS in sub-Saharan Africa and highlights the importance of screening for novel mutations in known genes when studying diverse global populations. This is important for counseling and prenatal diagnosis for high-risk families.