Missense mutations in the DNA-binding region and termination codon in PAX6

We have identified nine novel intragenic mutations of the PAX6 gene in 30 patients with aniridia. One patient with Wilms' tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR syndrome) had deletion of 11p and had lost the paternal PAX6 allele. Two patients had small deletions: a frameshift that should result in early termination of the PAX6 protein, and a frameshift that leads to a termination-site change and run-on into the 3' untranslated region (UTR). The other 27 patients had single base-pair mutations. Four had splicing defects; three had IVS6+1G>A, which was at a mutation hotspot in the PAX6 gene; 10 had premature termination (four 1024C>T [R203X], also at a mutation hotspot); and six had missense mutations. Missense mutation A321T (1378G>A) was a polymorphic change; the other five missense mutations were L46R, C52R, I56T, G73D, and I87K. These five codons are in the PAX6 paired domain and are highly conserved throughout the entire paired family. Seven patients had a mutation in the normal stop codon (TAA). This change leads to run-on into the 3' UTR and is also at a mutation hotspot. All 30 mutations should result in PAX6 haploinsufficiency. No correlation was observed between mutation sites and phenotypes.     

Genome Sequencing of Mycobacterium abscessus Isolates from Patients in the United States and Comparisons to Globally Diverse Clinical Strains

Nontuberculous mycobacterial infections caused by Mycobacterium abscessus are responsible for a range of disease manifestations from pulmonary to skin infections and are notoriously difficult to treat, due to innate resistance to many antibiotics. Previous population studies of clinical M. abscessus isolates utilized multilocus sequence typing or pulsed-field gel electrophoresis, but high-resolution examinations of genetic diversity at the whole-genome level have not been well characterized, particularly among clinical isolates derived in the United States. We performed whole-genome sequencing of 11 clinical M. abscessus isolates derived from eight U.S. patients with pulmonary nontuberculous mycobacterial infections, compared them to 30 globally diverse clinical isolates, and investigated intrapatient genomic diversity and evolution. Phylogenomic analyses revealed a cluster of closely related U.S. and Western European M. abscessus subsp. abscessus isolates that are genetically distinct from other European isolates and all Asian isolates. Large-scale variation analyses suggested genome content differences of 0.3 to 8.3%, relative to the reference strain ATCC 19977^T. Longitudinally sampled isolates showed very few single-nucleotide polymorphisms and correlated genomic deletion patterns, suggesting homogeneous infection populations. Our study explores the genomic diversity of clinical M. abscessus strains from multiple continents and provides insight into the genome plasticity of an opportunistic pathogen.     

Manubriosternal subluxation/dislocation can lead to manubriosternal septic arthritis in patients with kyphoscoliosis

Locally deranged joint anatomy can predispose to septic arthritis which can be managed by surgical debridement. We present a case of manubriosternal subluxation/dislocation caused by kyphoscoliosis leading to manubriosternal septic arthritis.     

Nasal mucosal administration of chitin microparticles boosts innate immunity against influenza A virus in the local pulmonary tissue

Influenza virus infection remains a major health concern due to morbidity and mortality associated with epidemics and occasional pandemics. The absence of acquired immunity to antigenically distinct, emerging virus strains stresses the need for a generic drug that protects independent of vaccination. Here, we demonstrate that prophylactic administration of chitin microparticles (CMP) via the intranasal route significantly reduced lung viral titres and clinical signs. Pre-treatment boosted the innate immune response to subsequent infection by recruiting innate cells, such as neutrophils, and increasing inflammatory cytokines. Although an increase in virus-specific T cells was observed, the memory phase was diminished. Our data demonstrate that in the absence of prior exposure to influenza virus, CMP reduce clinical signs by boosting innate immunity.     

Prediction of resting cardiovascular functioning in youth with family histories of essential hypertension: A 5-year follow-up

Two hundred forty-six children (96 Whites, of whom 51 were mates; 150 African- Americans, of whom 69 were males) with a familial history of essential hypertension (EH) were re-evaluated 5 years after an initial evaluation. During the initial visit, anthropometric, demographic, and resting cardiovascular (CV) parameters (designated initial baseline levels) were assessed. These CV parameters (systolic and diastolic blood pressure [BP], heart rate, cardiac output index [CI], and total peripheral resistance index [TPRI]) were also measured during postural challenge, a video game challenge, and a cold pressor task. At follow-up, resting CV parameters were again evaluated, and designated as follow-up resting levels. Moderate temporal stability (r range = .43-.56) was observed for all resting CV parameters. Mean stress responses for each CV parameter for all 3 stressors during the initial visit were positively related to the respective CV follow-up resting level. BP stress responses to postural change and video game challenge were found to be significant independent predictors of future resting BP after controlling for standard EH risk factors. Follow-up resting CI was not predicted by any stress responses, whereas follow-up resting TPRI was predicted by TPRI responses to the video game after controlling for standard EH risk Factors. These results contrast with those from an earlier 1-year follow-up. where stress responses for neither CI nor TPRI predicted follow-up resting levels. It appears that, as children get older. TPRI stress responses play a stronger role in vasoconstrictive function. This research was supported by National Institutes of Health Grant HL41781.     

Distribution of mutations in the PEX gene in families with X-linked hypophosphataemic rickets (HYP)

Mutations in the PEX gene at Xp22.1 (phosphate-regulating gene with homologies to endopeptidases, on the X-chromosome), are responsible for X-linked hypophosphataemic rickets (HYP). Homology of PEX to the M13 family of Zn2+ metallopeptidases which include neprilysin (NEP) as prototype, has raised important questions regarding PEX function at the molecular level. The aim of this study was to analyse 99 HYP families for PEX gene mutations, and to correlate predicted changes in the protein structure with Zn2+ metallopeptidase gene function. Primers flanking 22 characterised exons were used to amplify DNA by PCR, and SSCP was then used to screen for mutations. Deletions, insertions, nonsense mutations, stop codons and splice mutations occurred in 83% of families screened for in all 22 exons, and 51% of a separate set of families screened in 17 PEX gene exons. Missense mutations in four regions of the gene were informative regarding function, with one mutation in the Zn2+-binding site predicted to alter substrate enzyme interaction and catalysis. Computer analysis of the remaining mutations predicted changes in secondary structure, N-glycosylation, protein phosphorylation and catalytic site molecular structure. The wide range of mutations that align with regions required for protease activity in NEP suggests that PEX also functions as a protease, and may act by processing factor(s) involved in bone mineral metabolism.