Characterization of a recurrent missense mutation in the forkhead DNA-binding domain of \u3ci\u3eFOXP1\u3c/i\u3e

Haploinsufficiency of Forkhead box protein P1 (FOXP1), a highly conserved transcription factor, leads to developmental delay, intellectual disability, autism spectrum disorder, speech delay, and dysmorphic features. Most of the reported FOXP1 mutations occur on the C-terminus of the protein and cluster around to the forkhead domain. All reported FOXP1 pathogenic variants result in abnormal cellular localization and loss of transcriptional repression activity of the protein product. Here we present three patients with the same FOXP1 mutation, c.1574G\u3eA (p.R525Q), that results in the characteristic loss of transcription repression activity. This mutation, however, represents the first reported FOXP1 mutation that does not result in cytoplasmic or nuclear aggregation of the protein but maintains normal nuclear localization

Electrostatic carrier doping of GdTiO3/SrTiO3 interfaces

Heterostructures and superlattices consisting of a prototype Mott insulator, GdTiO3, and the band insulator SrTiO3 are grown by molecular beam epitaxy and show intrinsic electronic reconstruction, approximately 1/2 electron per surface unit cell at each GdTiO3/SrTiO3 interface. The sheet carrier densities in all structures containing more than one unit cell of SrTiO3 are independent of layer thicknesses and growth sequences, indicating that the mobile carriers are in a high concentration, two-dimensional electron gas bound to the interface. These carrier densities closely meet the electrostatic requirements for compensating the fixed charge at these polar interfaces. Based on the experimental results, insights into interfacial band alignments, charge distribution and the influence of different electrostatic boundary conditions are obtained.Comment: The article has been accepted by Applied Physics Letters. After it is published, it will be found at http://apl.aip.org

Seebeck coefficient of a quantum confined, high-electron-density electron gas in SrTiO 3

We report on the Seebeck coefficient of quantum confined electron gases in GdTiO3/SrTiO3heterostructures. These structures contain two-dimensional electron gases with very highsheet-carrier concentrations on the SrTiO3-side of the interface due to intrinsic interface doping.While the sheet carrier concentrations are independent of the thickness of the SrTiO3layer, theSeebeck coefficient initially increases with SrTiO3thickness before saturating at a value of300 lK/V. A model of the Seebeck coefficient, based on thermally populated, self-consistent,tight binding subbands, captures in a semi-quantitative manner the observed thickness dependence