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.

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.

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.