Ondřej Bonczek

PAX9 gene mutations and tooth agenesis: A review

Paired box 9 (PAX9) is one of the best‐known transcription factors involved in the development of human dentition. Mutations in PAX9 gene could, therefore, seriously influence the number, position and morphology of the teeth in an affected individual. To date, over 50 mutations in the gene have been reported as associated with various types of dental agenesis (congenitally missing teeth) and other inherited dental defects or variations. The most common consequence of PAX9 gene mutation is the autosomal‐dominant isolated (non‐syndromic) oligodontia or hypodontia.

A screen of a large Czech cohort of oligodontia patients implicates a novel mutation in the PAX9 gene

Tooth agenesis is one of the most common developmental anomalies in humans. To date, many mutations involving paired box 9 (PAX9), msh homeobox 1 (MSX1), and axin 2 (AXIN2) genes have been identified. The aim of the present study was to perform screening for mutations and/or polymorphisms using the capillary sequencing method in the critical regions of PAX9 and MSX1 genes in a group of 270 individuals with tooth agenesis and in 30 healthy subjects of Czech origin. This screening revealed a previously unknown heterozygous g.9527G>T mutation in the PAX9 gene in monozygotic twins with oligodontia and three additional affected family members. The same variant was not found in healthy relatives. This mutation is located in intron 2, in the region recognized as the splice site between exon 2 and intron 2. We hypothesize that the error in pre-mRNA splicing may lead to lower expression of PAX9 protein and could have contributed to the development of tooth agenesis in the affected subjects.

CD36 gene is associated with intraocular pressure elevation after intravitreal application of anti-VEGF agents in patients with age-related macular degeneration: Implications for the safety of the therapy

ABSTRACT Background: The wet form of age-related macular degeneration (AMD) is characterized by pathological vascularization of the outer retinal layers. The condition responds to treatment with antibodies against vascular endothelial growth factor (VEGF), but the patients receiving such anti-VEGF therapy sometimes show undesirable acute short-term increases in the intraocular pressure (IOP). The cause of this adverse effect is unknown, and here, we are testing a hypothesis that it is related to CD36 gene polymorphisms. Materials and Methods: A group of 134 patients with AMD were given three therapeutic doses of anti-VEGF antibody (ranibizumab) at monthly intervals. Their IOP was measured immediately before and 30 min after each injection. Patients’ DNA was analyzed, and the changes in IOP were matched against seven polymorphisms of the CD36 gene. Results: Three polymorphisms were found to be associated with increases in IOP: rs1049673 (p = 0.006), rs3211931 (p = 0.01), and rs1761667 (p = 0.043) at the time of the third injection only. Pronounced elevations (IOP > 25 mmHg) were associated with rs1049673 polymorphism: GC genotype (p < 0.01) and CC genotype (p < 0.05); both increasing the risk 2.6-fold, the presence of C-allele conferring a 1.5-fold greater risk and with rs3211931 polymorphism: AG genotype (p < 0.01) and GG genotype (p < 0.05); increasing the risk 2.6-fold (AG) and 2.7-fold (GG). Conclusions: CD36 receptor may be involved in mediating the effects of VEGF on IOP. The findings will help to identify the patients at risk of acutely elevated IOP following the anti-VEGF therapy.

Identification of Borrelia burgdorferi genospecies isolated from Ixodes ricinus ticks in the South Moravian region of the Czech Republic

INTRODUCTION During 2008-2012, a total of 466 ticks Ixodes ricinus removed from humans were collected and tested for the presence of Borrelia burgdorferi sensu lato (Bbsl). Ticks were collected in all districts of the South Moravian region of the Czech Republic (CZ). OBJECTIVE The aim of this study was to determine the infestation of Bbsl in ticks Ixodes ricinus and the identification of genospecies of Bbsl group by DNA sequencing. MATERIAL AND METHODS DNA isolation from homogenates was performed by UltraClean BloodSpin DNA kit (MoBio) and by automated instrument Prepito (Perkin-Elmer). Detection of spirochetes was carried out by RealTime PCR kit EliGene Borrelia LC (Elisabeth Pharmacon). Finally, all the positive samples were sequenced on an ABI 3130 Genetic Analyzer (Life Technologies) and identified in the BLAST (NCBI) database. RESULTS A total positivity of the samples was 26%. For the first time in the Czech Republic, 5 of the isolated strains were genotyped as Borrelia spielmanii (7.1%). Other representatives of Bbsl were also observed: B. afzelii (70.0%), B. garinii (10.0%), B. valaisiana (8.6%), and B. burgdorferi s. s. (4.3%). CONCLUSION A general view of the spreading of Bbsl in the South Moravian region was demonstrated. The most interesting result of the study is the finding of B. spielmanii for the first time in this region.

Next generation sequencing reveals a novel nonsense mutation in MSX1 gene related to oligodontia

Tooth agenesis is one of the most common craniofacial disorders in humans. More than 350 genes have been associated with teeth development. In this study, we enrolled 60 child patients (age 13 to 17) with various types of tooth agenesis. Whole gene sequences of PAX9, MSX1, AXIN2, EDA, EDAR and WNT10a genes were sequenced by next generation sequencing on the Illumina MiSeq platform. We found previously undescribed heterozygous nonsense mutation g.8177G>T (c.610G>T) in MSX1 gene in one child. Mutation was verified by Sanger sequencing. Sequencing analysis was performed in other family members of the affected child. All family members carrying g.8177G>T mutation suffered from oligodontia (missing more than 6 teeth excluding third molars). Mutation g.8177G>T leads to a stop codon (p.E204X) and premature termination of Msx1 protein translation. Based on previous in vitro experiments on mutation disrupting function of Msx1 homeodomain, we assume that the heterozygous g.8177G>T nonsense mutation affects the amount and function of Msx1 protein and leads to tooth agenesis.