The Colors of Mixtures of Dental Opaque Porcelains

The colors of mixtures of dental opaque porcelains and modifiers were measured with use of the CIE L*a * b* uniform color space. Mixtures of dental porcelains were tested to duplicate the range of human tooth colors. Vertical movements in the yellow and blue directions were obtained. Horizontal movements in the red and green directions were achieved. Reflectance measurements were made with use of a spectrophotometer with an integrating sphere. Spectrophotometer measurements were converted to absolute reflectance and then used to calculate CIE a* b* values for a 2° standard observer and for illuminant C. Movements in the yellow, red, blue, and green directions for adequate simulation of the tooth color range can be demonstrated with use of dental opaque and modifier porcelains.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67312/2/10.1177_00220345890680090601.pd

De novo variants in the RNU4-2 snRNA cause a frequent neurodevelopmental syndrome

Around 60% of individuals with neurodevelopmental disorders (NDD) remain undiagnosed after comprehensive genetic testing, primarily of protein-coding genes1. Large genome-sequenced cohorts are improving our ability to discover new diagnoses in the non-coding genome. Here, we identify the non-coding RNA RNU4-2 as a syndromic NDD gene. RNU4-2 encodes the U4 small nuclear RNA (snRNA), which is a critical component of the U4/U6.U5 tri-snRNP complex of the major spliceosome2. We identify an 18 bp region of RNU4-2 mapping to two structural elements in the U4/U6 snRNA duplex (the T-loop and Stem III) that is severely depleted of variation in the general population, but in which we identify heterozygous variants in 115 individuals with NDD. Most individuals (77.4%) have the same highly recurrent single base insertion (n.64_65insT). In 54 individuals where it could be determined, the de novo variants were all on the maternal allele. We demonstrate that RNU4-2 is highly expressed in the developing human brain, in contrast to RNU4-1 and other U4 homologs. Using RNA-sequencing, we show how 5’ splice site usage is systematically disrupted in individuals with RNU4-2 variants, consistent with the known role of this region during spliceosome activation. Finally, we estimate that variants in this 18 bp region explain 0.4% of individuals with NDD. This work underscores the importance of non-coding genes in rare disorders and will provide a diagnosis to thousands of individuals with NDD worldwide