Delineating the psychiatric and behavioral phenotype of recurrent 2q13 deletions and duplications

Recurrent deletions and duplications at the 2q13 locus have been associated with developmental delay (DD) and dysmorphisms. We aimed to undertake detailed clinical characterization of individuals with 2q13 copy number variations (CNVs), with a focus on behavioral and psychiatric phenotypes. Participants were recruited via the Unique chromosomal disorder support group, U.K. National Health Service Regional Genetics Centres, and the DatabasE of genomiC varIation and Phenotype in Humans using Ensembl Resources (DECIPHER) database. A review of published 2q13 patient case reports was undertaken to enable combined phenotypic analysis. We present a new case series of 2q13 CNV carriers (21 deletion, 4 duplication) and the largest ever combined analysis with data from published studies, making a total of 54 deletion and 23 duplication carriers. DD/intellectual disabilities was identified in the majority of carriers (79% deletion, 70% duplication), although in the new cases 52% had an IQ in the borderline or normal range. Despite the median age of the new cases being only 9 years, 64% had a clinical psychiatric diagnosis. Combined analysis found attention deficit hyperactivity disorder (ADHD) to be the most frequent diagnosis (48% deletion, 60% duplication), followed by autism spectrum disorders (33% deletion, 17% duplication). Aggressive (33%) and self-injurious behaviors (33%) were also identified in the new cases. CNVs at 2q13 are typically associated with DD with mildly impaired intelligence, and a high rate of childhood psychiatric diagnoses-particularly ADHD. We have further characterized the clinical phenotype related to imbalances of the 2q13 region and identified it as a region of interest for the neurobiological investigation of ADHD.

Sox2 is required for sensory organ development in the mammalian inner ear

Sensory hair cells and their associated non-sensory supporting cells in the inner ear are fundamental for hearing and balance. They arise from a common progenitor, but little is known about the molecular events specifying this cell lineage. We recently identified two allelic mouse mutants, light coat and circling (Lcc) and yellow submarine (Ysb), that show hearing and balance impairment. Lcc/Lcc mice are completely deaf, whereas Ysb/Ysb mice are severely hearing impaired. We report here that inner ears of Lcc/Lcc mice fail to establish a prosensory domain and neither hair cells nor supporting cells differentiate, resulting in a severe inner ear malformation, whereas the sensory epithelium of Ysb/Ysb mice shows abnormal development with disorganized and fewer hair cells. These phenotypes are due to the absence (in Lcc mutants) or reduced expression (in Ysb mutants) of the transcription factor SOX2, specifically within the developing inner ear. SOX2 continues to be expressed in the inner ears of mice lacking Math1 (also known as Atoh1 and HATH1), a gene essential for hair cell differentiation, whereas Math1 expression is absent in Lcc mutants, suggesting that Sox2 acts upstream of Math1.

Screening of basidiomycetes and xylariaceous fungi for lignin peroxidase and laccase gene-specific sequences

Lignin peroxidase and laccase gene-specific PCR primers were used to screen 38 diverse basidiomycetes and xylariaceous fungi. Lignin peroxidase gene-specific sequences were obtained for basidiomycetes only and were highly divergent. Possession of laccase genes was relatively widespread among basidiomycetes, and is shown for the first time in Xylariaceae. All sequences were highly conserved with no variation resulting in changes to predicted amino acid sequence. Those basidiomycetes shown to possess lignin peroxidase and laccase genes also produced the enzyme in vitro. Conversely none of the xylariaceous fungi shown to possess laccase genes were able to do so, whilst others decolorized Poly R yet yielded no PCR amplicons.

Circling, deafness, and yellow coat displayed by yellow submarine (ysb) and light coat and circling (lcc) mice with mutations on chromosome 3

We describe here two mouse mutants, yellow submarine (Ysb) and light coat and circling (Lcc). Ysb arose as the result of insertions of a transgene, pAA2, into the genome. Lcc is an independent, radiation-induced mutation. Both mutants are characterized by recessive circling behavior and deafness, associated with a non-segregating, semi-dominant yellow coat color. Complementation tests showed that Ysb and Lcc are allelic. We attribute the yellow coat in Ysb and Lcc mice to the absence of black awl overhairs, increased agouti zigzag underhairs, and the presence of agouti awls with long subapical yellow pigment. Chromosomal mapping and genomic characterization showed the Ysb and Lcc mutations involve complex chromosomal rearrangements in overlapping regions of mouse chromosome 3, A2/A3-B/C and B-E1, respectively. Ysb and Lcc show for the first time, to our knowledge, the presence of genes in the B-C region of chromosome 3 important for balance and hearing and the pigmentation and specification of coat hair.

A human genomic library enriched in transcriptionally active sequences (aDNA library)

Core histone hyperacetylation, in particular of H4, is concentrated in the promoter-upstream regions of active genes and in certain cases is locuswide. Antibodies to hyperacetylated H4 were used to immunoprecipitate dinucleosomal chromatin derived from K562 human erythroleukemic cells by micrococcal nuclease digestion. The extracted DNA was made into a genomic library and was expected to contain sequences from genes active in K562 cells (an active, 'aDNA' library). Clones (180) were randomly selected from the library; 24 of 103 tested (23%) contained highly repeated sequences, as determined by their hybridization to total genomic DNA, and were not analyzed further. An additional 10 clones (6%) were shown to contain no insert DNA. The remaining 146 were sequenced and compared with the nucleic acid databases and in all six frames to the protein databases: Sixeen clones could be assigned to known genes, the majority of which (12) were tissue specific. All but 2 of these 16 corresponded to segments 5' of the coding sequences, as expected if H4 acetylation is concentrated at promoter regions. Thirty-three clones (23%) displayed high sequence identity to cDNAs in the expressed sequence tag database (dbEST). Northern blots and reverse transcription (RT)-PCR were used to determine the proportion of clones representing sequences expressed in K562 cells: Although only 1 of 34 tested clones showed a band in Northern hybridization, RT-PCR demonstrated that at least 12 of 40 tested clones (30%) were present in the mRNA population. Because a further 8 of these 40 clones were identified as gene fragments by database sequence comparisons, it follows that about half of this subset of 40 clones is derived from genes. The aDNA library is thus very gene rich and not skewed toward the most highly expressed sequences, as in mRNA libraries. The aDNA library is also rich in promoters and could be a valuable source of such sequences, particularly those that lack CpG islands or other features that allow their specific selection.