Peter Twumasi

Establishing in vitro Zinnia elegans cell suspension culture with high tracheary element differentiation.

The Zinnia elegans mesophyll cell culture is a useful system for xylogenesis studies. The system is associated with highly synchronous tracheary element (TE) differentiation, making it more suitable for molecular studies requiring larger amounts of molecular isolates, such as mRNA and proteins and for studying cellulose synthesis. There is, however, the problem of non‐uniformity and significant variations in the yields of TEs (%TE). One possible cause for this variability in the%TE could be the lack of a standardized experimental protocol in various research laboratories for establishing the Zinnia culture. Mesophyll cells isolated from the first true leaves of Z. elegans var Envy seedlings of approximately 14 days old were cultured in vitro and differentiated into TEs. The xylogenic culture medium was supplied with 1 mg/l each of benzylaminopurine (BA) and α‐naphthalene acetic acid (NAA). Application of this improved culture method resulted in stable and reproducible amounts of TE as high as 76% in the Zinnia culture. The increase was mainly due to conditioning of the mesophyll cell culture and adjustments of the phytohormonal balance in the cultures. Also, certain biochemical and cytological methods have been shown to reliably monitor progress of TE differentiation. We conclude that, with the adoption of current improvement in the xylogenic Z. elegans culture, higher amounts of tracheary elements can be produced. This successful outcome raises the potential of the Zinnia system as a suitable model for cellulose and xylogenesis research.

Pica practice among pregnant women in the Kumasi metropolis of Ghana

Pica, an eating disorder in which non-nutritional objects are frequently eaten, has negative health implications. Despite this, pica is less studied in many African communities where it is believed to be highly prevalent. This study therefore sought to determine the prevalence of pica and its various forms among pregnant women in Kumasi, Ghana, and the effects of education and place of residence (rural and urban) on pica practice. A random sample of pregnant women (n = 400) in rural and urban areas of Kumasi were interviewed using a questionnaire-based survey in 2008 and repeated in 2009. The results showed 47.0% of the pregnant women practising pica. Pagophagia accounted for 41.0%, followed by geophagia (29.8%), amylophagia (7.4%), plumbophagia (6.4%), and trichophagia (3.7%). Among the rural dwellers, 47.7% of the pregnant women practised pica during their pregnancies while 46.4% of the urban pregnant women engaged in the practice. Age and level of education did not significantly affect the practice of pica (P = 0.053 and P = 0.142 respectively). Also, 17.4% of the respondents identified a family member practising pica. Pica is therefore highly prevalent in pregnant women in Kumasi, with pagophagia and geophagia being the predominant types of pica.

Association Studies and Direct DNA Sequencing Implicate Genetic Susceptibility Loci in the Etiology of Nonsyndromic Orofacial Clefts in Sub-Saharan African Populations

Orofacial clefts (OFCs) are congenital dysmorphologies of the human face and oral cavity, with a global incidence of 1 per 700 live births. These anomalies exhibit a multifactorial pattern of inheritance, with genetic and environmental factors both playing crucial roles. Many loci have been implicated in the etiology of nonsyndromic cleft lip with or without cleft palate (NSCL/P) in populations of Asian and European ancestries, through genome-wide association studies and candidate gene studies. However, few populations of African descent have been studied to date. Here, the authors show evidence of an association of some loci with NSCL/P and nonsyndromic cleft palate only (NSCPO) in cohorts from Africa (Ghana, Ethiopia, and Nigeria). The authors genotyped 48 single-nucleotide polymorphisms that were selected from previous genome-wide association studies and candidate gene studies. These markers were successfully genotyped on 701 NSCL/P and 163 NSCPO cases, 1,070 unaffected relatives, and 1,078 unrelated controls. The authors also directly sequenced 7 genes in 184 nonsyndromic OFC (NSOFC) cases and 96 controls from Ghana. Population-specific associations were observed in the case-control analyses of the subpopulations, with West African subpopulations (Ghana and Nigeria) showing a similar pattern of associations. In meta-analyses of the case-control cohort, PAX7 (rs742071, P = 5.10 × 10−3), 8q24 (rs987525, P = 1.22 × 10−3), and VAX1 (rs7078160, P = 0.04) were nominally associated with NSCL/P, and MSX1 (rs115200552, P = 0.01), TULP4 (rs651333, P = 0.04), CRISPLD2 (rs4783099, P = 0.02), and NOG1 (rs17760296, P = 0.04) were nominally associated with NSCPO. Moreover, 7 loci exhibited evidence of threshold overtransmission in NSOFC cases through the transmission disequilibrium test and through analyses of the family-based association for disease traits. Through DNA sequencing, the authors also identified 2 novel, rare, potentially pathogenic variants (p.Asn323Asp and p.Lys426IlefsTer6) in ARHGAP29. In conclusion, the authors have shown evidence for the association of many loci with NSCL/P and NSCPO. To the best of this knowledge, this study is the first to demonstrate any of these association signals in any African population.

Loss-of-Function GRHL3 Variants Detected in African Patients with Isolated Cleft Palate

In contrast to the progress that has been made toward understanding the genetic etiology of cleft lip with or without cleft palate, relatively little is known about the genetic etiology for cleft palate only (CPO). A common coding variant of grainyhead like transcription factor 3 (GRHL3) was recently shown to be associated with risk for CPO in Europeans. Mutations in this gene were also reported in families with Van der Woude syndrome. To identify rare mutations in GRHL3 that might explain the missing heritability for CPO, we sequenced GRHL3 in cases of CPO from Africa. We recruited participants from Ghana, Ethiopia, and Nigeria. This cohort included case-parent trios, cases and other family members, as well as controls. We sequenced exons of this gene in DNA from a total of 134 nonsyndromic cases. When possible, we sequenced them in parents to identify de novo mutations. Five novel mutations were identified: 2 missense (c.497C>A; p.Pro166His and c.1229A>G; p.Asp410Gly), 1 splice site (c.1282A>C p.Ser428Arg), 1 frameshift (c.470delC; p.Gly158Alafster55), and 1 nonsense (c.1677C>A; p.Tyr559Ter). These mutations were absent from 270 sequenced controls and from all public exome and whole genome databases, including the 1000 Genomes database (which includes data from Africa). However, 4 of the 5 mutations were present in unaffected mothers, indicating that their penetrance is incomplete. Interestingly, 1 mutation damaged a predicted sumoylation site, and another disrupted a predicted CK1 phosphorylation site. Overexpression assays in zebrafish and reporter assays in vitro indicated that 4 variants were functionally null or hypomorphic, while 1 was dominant negative. This study provides evidence that, as in Caucasian populations, mutations in GRHL3 contribute to the risk of nonsyndromic CPO in the African population.

The prevalence, penetrance, and expressivity of etiologicIRF6variants in orofacial clefts patients from sub-Saharan Africa

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.