Whole genome sequencing of a family with autosomal dominant features within the oculoauriculovertebral spectrum.

Background: Oculoauriculovertebral Spectrum (OAVS) encompasses a wide variety of anomalies on derivatives from the first and second pharyngeal arches including macrostomia, hemifacial microsomia, micrognathia, preauricular tags, ocular and vertebral anomalies. We present the genetic findings of a large three-generation family with multiple members affected with macrostomia, preauricular tags and uni- or bilateral ptosis following an autosomal dominant segregation pattern. Methods: We generated whole genome sequencing data for the proband, affected parent and unaffected paternal grandparent followed by Sanger sequencing on 23 family members for the top 10 candidate genes: KCND2, PDGFRA, CASP9, NCOA3, WNT10A, SIX1, MTF1, KDR/VEGFR2, LRRK1, and TRIM2. We performed parent and sibling-based transmission disequilibrium tests and burden analysis to explore segregation and burden of candidate gene mutations. Bioinformatic analyses investigated the biological connection between genes and the abnormal phenotypes. Results: Overall, rare missense mutations in SIX1, KDR/VEGFR2, and PDGFRA showed the best evidence of segregation with the OAV phenotypes in this family. When considering affection with any of the 3 OAVS phenotypes as an outcome, parent-TDTs and sib-TDTs (unadjusted p-values) found that SIX1 (p=0.025, p=0.052), followed by PDGFRA (p=0.180, p=0.069) and KDR/VEGFR2 (p=0.180, p=0.069) have the strongest associations in this family. Burden analysis via a penalized linear mixed model identified SIX1 (RC=0.87) and PDGFRA (RC=0.98) as having the strongest association with OAVS severity. Using phenotype-specific ogfrautcomes, sib-TDTs identified associations between (1) SIX1 with uni- or bilateral ptosis (p=0.049) and ear tags (p=0.01), (2) PDGFRA and KDR/VEGFR2 with ear tags (both p<0.01). Conclusion: Our study reports the genomic findings of a large family with multiple individuals affected with OAVS phenotypes with autosomal dominant inheritance. Our findings narrow down to three potential candidate genes, SIX1, PDGFRA, and KDR/VEGFR2. Among these, SIX1 has been previously associated with OAVS ear malformations and it is co-expressed with EYA1 during ear development. Attempts to strengthen the genotype-phenotype co-relation underlying the OAVS of phenotypes are essential to discover the etiological factors leading to this complex and burdensome condition as well as for family counseling and prevention efforts.

MEMO1 Is Required for Ameloblast Maturation and Functional Enamel Formation.

Coordinated mineralization of soft tissue is central to organismal form and function, while dysregulated mineralization underlies several human pathologies. Oral epithelial-derived ameloblasts are polarized, secretory cells responsible for generating enamel, the most mineralized substance in the human body. Defects in ameloblast development result in enamel anomalies, including amelogenesis imperfecta. Identifying proteins critical in ameloblast development can provide insight into specific pathologies associated with enamel-related disorders or, more broadly, mechanisms of mineralization. Previous studies identified a role for MEMO1 in bone mineralization; however, whether MEMO1 functions in the generation of additional mineralized structures remains unknown. Here, we identify a critical role for MEMO1 in enamel mineralization. First, we show that Memo1 is expressed in ameloblasts and, second, that its conditional deletion from ameloblasts results in enamel defects, characterized by a decline in mineral density and tooth integrity. Histology revealed that the mineralization defects in Memo1 mutant ameloblasts correlated with a disruption in ameloblast morphology. Finally, molecular profiling of ameloblasts and their progenitors in Memo1 oral epithelial mutants revealed a disruption to cytoskeletal-associated genes and a reduction in late-stage ameloblast markers, relative to controls. Collectively, our findings integrate MEMO1 into an emerging network of molecules important for ameloblast development and provide a system to further interrogate the relationship of cytoskeletal and amelogenesis-related defects.

Application of a prediction model for work-related sensitisation in bakery workers.

Identification of work-related allergy, particularly work-related asthma, in a (nationwide) medical surveillance programme among bakery workers requires an effective and efficient strategy. Bakers at high risk of having work-related allergy were indentified by use of a questionnaire-based prediction model for work-related sensitisation. The questionnaire was applied among 5,325 participating bakers. Sequential diagnostic investigations were performed only in those with an elevated risk. Performance of the model was evaluated in 674 randomly selected bakers who participated in the medical surveillance programme and the validation study. Clinical investigations were evaluated in the first 73 bakers referred at high risk. Overall 90% of bakers at risk of having asthma could be identified. Individuals at low risk showed 0.3-3.8% work-related respiratory symptoms, medication use or absenteeism. Predicting flour sensitisation by a simple questionnaire and score chart seems more effective at detecting work-related allergy than serology testing followed by clinical investigation in all immunoglobulin E class II-positive individuals. This prediction based stratification procedure appeared effective in detecting work-related allergy among bakers and can accurately be used for periodic examination, especially in small enterprises where delivery of adequate care is difficult. This approach may contribute to cost reduction.