Linkage of a familial platelet disorder with a propensity to develop myeloid malignancies to human chromosome 21q22.1-22.2

Linkage analysis was performed on a large pedigree with an autosomal dominant platelet disorder and a striking propensity in affected family members to develop hematologic malignancy, predominantly acute myelogenous leukemia. We report the linkage of the autosomal dominant platelet disorder to markers on chromosome 21q22. Four genetic markers completely cosegregate with the trait and yield maximum logarithm of difference scores ranging from 4.9 to 10.5 (θ = .001). Two flanking markers, D21S1265 and D21S167, define a critical region for the disease locus of 15.2 centimorgan. Further analysis of this locus may identify a gene product that affects platelet production and function and contributes to the molecular evolution of hematologic malignancy.7 page(s

Identification of rare recurrent copy number variants in high-risk autism families and their prevalence in a large ASD population.

Structural variation is thought to play a major etiological role in the development of autism spectrum disorders (ASDs), and numerous studies documenting the relevance of copy number variants (CNVs) in ASD have been published since 2006. To determine if large ASD families harbor high-impact CNVs that may have broader impact in the general ASD population, we used the Affymetrix genome-wide human SNP array 6.0 to identify 153 putative autism-specific CNVs present in 55 individuals with ASD from 9 multiplex ASD pedigrees. To evaluate the actual prevalence of these CNVs as well as 185 CNVs reportedly associated with ASD from published studies many of which are insufficiently powered, we designed a custom Illumina array and used it to interrogate these CNVs in 3,000 ASD cases and 6,000 controls. Additional single nucleotide variants (SNVs) on the array identified 25 CNVs that we did not detect in our family studies at the standard SNP array resolution. After molecular validation, our results demonstrated that 15 CNVs identified in high-risk ASD families also were found in two or more ASD cases with odds ratios greater than 2.0, strengthening their support as ASD risk variants. In addition, of the 25 CNVs identified using SNV probes on our custom array, 9 also had odds ratios greater than 2.0, suggesting that these CNVs also are ASD risk variants. Eighteen of the validated CNVs have not been reported previously in individuals with ASD and three have only been observed once. Finally, we confirmed the association of 31 of 185 published ASD-associated CNVs in our dataset with odds ratios greater than 2.0, suggesting they may be of clinical relevance in the evaluation of children with ASDs. Taken together, these data provide strong support for the existence and application of high-impact CNVs in the clinical genetic evaluation of children with ASD

UCSC Genome browser view of CNVs in the <i>NRXN1</i> region.

<p>CNVs observed in the vicinity of the <i>NRXN1-alpha</i> transcription start site are shown. Note that most CNVs observed in ASD patients include exon 1 of <i>NRXN1-alpha</i> while only 1 control CNV extends into exon 1. Produced with custom tracks listing CNV calls and uploaded to <a href="http://genome.ucsc.edu" target="_blank">http://genome.ucsc.edu</a>.</p

UCSC Genome Browser View of CNVs in the GABR Region on chromosome 15q12.

<p>Duplications were called by both PennCNV and by CNAM in this region, however the number of duplications called by each program differed, with many additional duplications called by CNAM. Produced with custom tracks listing CNV calls and uploaded to <a href="http://genome.ucsc.edu" target="_blank">http://genome.ucsc.edu</a>.</p

Workflow for CNV analysis for samples analyzed on the custom array.

<p>The same process was used for both CNAM and PennCNV analyses. All samples used for CNV analysis in this study had to meet the quality control measures described. Only unrelated cases and controls were used for the final statistical analysis.</p

Published CNVs observed in our sample population.

*<p>Denotes CNVs contiguous with the chromosome 15q11.2–13.1 CNV shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052239#pone-0052239-t003" target="_blank">Table 3</a>.</p

Top Significant Biological Functions identified by Ingenuity IPA and literature searches.

<p>The right-tailed Fisher's exact test was used to calculate P-values representing the probability that selecting genes associated with that pathway or network is due to chance alone. Each functional category represents a collection of associated subcategories, each of which has an associated P-value. For example, within ‘Neurological Disease,’ are subcategories of genes associated with seizures, Huntington Disease, schizophrenia, etc. The P-value range given represents the range of P-values generated for each subcategory. In the first line, 14 genes were associated with a function in Neurological Disease by Ingenuity software. An additional 4 genes were identified as having neurological functions in the literature, giving a total of 18 with known or suspected roles in neurological disease.</p

Confirmation of CNV calls by quantitative PCR.

<p>A summary of the PCR validation result is shown. Sequence SNP CNVs were discovered in this work using SNVs present on this array for sequence variant confirmation in the same cohort.</p

Manhattan plot of CNVs called both by PennCNV and CNAM.

<p>Association statistics across all regions covered on the Illumina custom array are shown. Since the array used was not a genome-wide array, the width of each chromosome on the plot is not proportional to the chromosome length. Adjacent chromosomes are displayed in alternating red and blue colors to aid in distinguishing them.</p