Inverted repeats (IRs) can facilitate structural variation as crucibles of genomic rearrangement. Complex duplication—inverted triplication—duplication (DUP-TRP/INV-DUP) rearrangements that contain breakpoint junctions within IRs have been recently associated with both MECP2 duplication syndrome (MIM#300260) and Pelizaeus-Merzbacher disease (PMD, MIM#312080). We investigated 17 unrelated PMD subjects with copy number gains at the PLP1 locus including triplication and quadruplication of specific genomic intervals—16/17 were found to have a DUP-TRP/INV-DUP rearrangement product. An IR distal to PLP1 facilitates DUP-TRP/INV-DUP formation as well as an inversion structural variation found frequently amongst normal individuals. We show that a homology—or homeology—driven replicative mechanism of DNA repair can apparently mediate template switches within stretches of microhomology. Moreover, we provide evidence that quadruplication and potentially higher order amplification of a genomic interval can occur in a manner consistent with rolling circle amplification as predicted by the microhomology-mediated break induced replication (MMBIR) model.

Insulin-like 3 (INSL3) signaling directs fetal gubernacular development and testis descent, but the actions of INSL3 in the gubernaculum are poorly understood. Using microarray gene expression profiling of fetal male rat gubernaculum explants exposed to 10 or 100 nM INSL3, significant changes in expression were identified for approximately 900 genes. Several of the genes showing the largest inductions regulate neuronal development or activity, including Pnoc (34-fold), Nptx2 (9-fold), Nfasc (4-fold), Gfra3 (3-fold), Unc5d (3-fold), and Crlf1 (3-fold). Bioinformatics analysis revealed BMP and WNT signaling pathways and several gene ontologies related to neurogenesis were altered by INSL3. Promoter response elements significantly enriched in the INSL3-regulated gene list included consensus sequences for MYB, REL, ATF2, and TEF transcription factors. Comparing in vivo gene expression profiles of male and female rat fetal gubernaculum showed expression of the Bmp, Wnt, and neurodevelopmental genes induced by INSL3 was higher in males. Using quantitative RT-PCR, the microarray data were confirmed, and the induction of Bmp3, Chrdl2, Crlf1, Nptx2, Pnoc, Wnt4, and Wnt5a mRNA levels were examined over a range of INSL3 concentrations (0.1-100 nM) in male and female gubernaculum. In both sexes, an increasing gene expression response was observed between 0.1 and 10 nM INSL3. These data suggest that INSL3 signaling in the fetal gubernaculum induces morphogenetic programs, including BMP and WNT signaling, and support other rodent data suggesting a role for these pathways in development of the gubernaculum.

Development of the fetal gubernaculum is a prerequisite for testicular descent and dependent on insulin-like 3 and androgen, but knowledge of downstream effectors is limited. We analyzed transcript profiles in gubernaculum and testis to address changes occurring during normal and abnormal testicular descent in Long Evans wild-type (wt) and cryptorchid (orl) fetuses. Total RNA from male wt and orl gubernacula (gestational days [GD]18-20), wt female gubernacula (GD18), and testis (GD17 and 19) was hybridized to Affymetrix GeneChips. Statistical analysis of temporal, gender, and strain-specific differences in gene expression was performed with the use of linear models analysis with empirical Bayes statistics and analysis of variance (gubernaculum) and linear analysis (testis). Overrepresented common gene ontology functional categories and pathways were identified in groups of differentially expressed genes with the Database for Annotation, Visualization, and Integrated Discovery. Transcript profiles were dynamic in wt males between GD18-19 and GD20, comparatively static in orl GD18-20 gubernaculum, and similar in wt and orl testis. Functional analysis of differentially expressed genes in wt and orl gubernaculum identified categories related to metabolism, cellular biogenesis, small GTPase-mediated signal transduction, cytoskeleton, muscle development, and insulin signaling. Genes involved in androgen receptor signaling, regulated by androgens, or both were overrepresented in differentially expressed gubernaculum and testis gene groups. Quantitative reverse transcription polymerase chain reaction (RT-PCR) confirmed differential expression of genes related to muscle development, including Myog, Tnnt2, Fst, Igf1, Igfbp5, Id2, and Msx1. These data suggest that the orl mutation results in a primary gubernacular defect that affects muscle development and cytoskeletal function and might alter androgen-regulated pathways.

Age at diagnosis is a key prognostic factor in pediatric acute lymphoblastic leukemia (ALL) survivorship. However, literature providing adequate assessment of the survival variability by age at diagnosis is scarce. The aim of this study is to assess the impact of this prognostic factor in pediatric ALL survival. We estimated incidence rate of mortality, 5-year survival rate, Kaplan-Meier survival function, and hazard ratio using the Surveillance Epidemiology and End Results (SEER) data during 1973–2009. There was significant variability in pediatric ALL survival by age at diagnosis. Survival peaked among children diagnosed at 1–4 years and steadily declined among those diagnosed at older ages. Infants (<1 year) had the lowest survivorship. In a multivariable Cox proportional hazard model stratified by year of diagnosis, those diagnosed in age groups 1–4, 5–9, 10–14, and 15–19 years were 82%, 75%, 57%, and 32% less likely to die compared to children diagnosed in infancy, respectively. Age at diagnosis remained to be a crucial determinant of the survival variability of pediatric ALL patients, after adjusting for sex, race, radiation therapy, primary tumor sites, immunophenotype, and year of diagnosis. Further research is warranted to disentangle the effects of age-dependent biological and environmental processes on this association.