An Anomaly with Potential as a New Prognostic Marker in CLL with del(13q): Gain of 16p13.3

Deletion 13q [del(13q)] is a favorable prognostic marker if it is detected as a sole abnormality in chronic lymphocytic leukemia (CLL). However the clinical courses of cases with isolated del(13q) are quite heterogeneous. In our study, we investigated copy number variations (CNVs), loss of heterozygosity (LOH), and the size of del(13q) in 30 CLL patients with isolated del(13q). We used CGH+SNP microarrays in order to understand the cause of this clinical heterogeneity. We detected del(13q) in 28/30 CLL cases. The size of the deletion varied from 0.34 to 28.81 Mb, and there was no clinical effect of the deletion size. We found new prognostic markers, especially the gain of 16p13.3. These markers have statistically significant associations with short time to first treatment and advanced disease stage. Detecting both CNVs and LOH at the same time is an advantageous feature of aCGH+SNP. However, it is very challenging for the array analysis to detect mosaic anomalies. Therefore, it is very important to confirm the results by FISH. In our study, we detected approximately 9% mosaic del(13q) by microarray. In addition, the gain of 16p13.3 may affect the disease prognosis in CLL. However, additional studies with more patients are needed to confirm these results.

Targeted genome-wide SNP genotyping in feral horses using non-invasive fecal swabs

The development of high-throughput sequencing has prompted a transition in wildlife genetics from using microsatellites toward sets of Single Nucleotide Polymorphisms (SNPs). However, genotyping large numbers of targeted SNPs using non-invasive samples remains challenging due to relatively large DNA input requirements. Recently, target enrichment has emerged as a promising approach requiring little template DNA. We assessed the efficacy of Tecan Genomics’ Allegro Targeted Genotyping (ATG) for generating genome-wide SNP data in feral horses using DNA isolated from fecal swabs. Total and host-specific DNA were quantified for 989 samples collected as part of a long-term individual-based study of feral horses on Sable Island, Nova Scotia, Canada, using dsDNA fluorescence and a host-specific qPCR assay, respectively. Forty-eight samples representing 44 individuals containing at least 10ng of host DNA (ATG’s recommended minimum input) were genotyped using a custom multiplex panel targeting 279 SNPs. Genotyping accuracy and consistency were assessed by contrasting ATG genotypes with those obtained from the same individuals with SNP microarrays, and from multiple samples from the same horse, respectively. 62% of swabs yielded the minimum recommended amount of host DNA for ATG. Ignoring samples that failed to amplify, ATG recovered an average of 86.7% targeted sites per sample, while genotype concordance between ATG and SNP microarrays was 98.5%. The repeatability of genotypes from the same individual approached unity with an average of 99.9%. This study demonstrates the suitability of ATG for genome-wide, non-invasive targeted SNP genotyping, and will facilitate further ecological and conservation genetics research in equids and related species.

The study of chromosomal abnormalities in fetuses with ultrasound markers and malformations

Микроделеционные и микродупликационные синдромы выявляются примерно у 8% плодов с врожденными пороками развития (ВПР), однако диагностика патогенных CNVs в пренатальном периоде в данный момент не регламентирована и зачастую основана на технических возможностях лаборатории. Представлены результаты исследования плодов, которые имели ВПР и/или маркеры хромосомной патологии, установленные по УЗИ, методом хромосомного микроматричного анализа (ХМА). В выборке (N=1048) у 10,3% плодов были обнаружены числовые аномалии хромосом и у 7,4% плодов были выявлены патогенные хромосомные аномалии, которые невозможно выявить при стандартном кариотипировани из-за их малого размера. Результаты нашего анализа согласуются с данными литературы, демонстрирующей большую эффективность SNP-микроматриц по сравнению с классическими цитогенетическими методами. Microdeletion and microduplication syndromes are detected in approximately 8% of fetuses with congenital malformations, however, the diagnosis of pathogenic CNVs in the prenatal period, at the moment, is unregulated and often based on the technical capabilities of the laboratory. The thesis presents the result of a study of fetuses that had congenital malformations and / or markers of chromosomal abnormalities, determined by ultrasound, by the method of chromosomal microarray analysis. Using chromosomal microarray analysis in our sample (N = 1048), numerical chromosome abnormalities were detected in 10.3% of the fetuses and pathogenic chromosome imbalance was revealed in 7.4% of the fetuses, which cannot be detected by standard karyotyping. The results of our analysis are consistent with the data of the scientific literature, which demonstrates the greater efficiency of using SNP microarrays in comparison with classical cytogenetic methods.

Ancient Ancestry Informative Markers for Identifying Fine-Scale Ancient Population Structure in Eurasians

The rapid accumulation of ancient human genomes from various areas and time periods potentially enables the expansion of studies of biodiversity, biogeography, forensics, population history, and epidemiology into past populations. However, most ancient DNA (aDNA) data were generated through microarrays designed for modern-day populations, which are known to misrepresent the population structure. Past studies addressed these problems by using ancestry informative markers (AIMs). It is, thereby, unclear whether AIMs derived from contemporary human genomes can capture ancient population structures, and whether AIM-finding methods are applicable to aDNA, provided that the high missingness rates in ancient—and oftentimes haploid—DNA can also distort the population structure. Here, we define ancient AIMs (aAIMs) and develop a framework to evaluate established and novel AIM-finding methods in identifying the most informative markers. We show that aAIMs identified by a novel principal component analysis (PCA)-based method outperform all of the competing methods in classifying ancient individuals into populations and identifying admixed individuals. In some cases, predictions made using the aAIMs were more accurate than those made with a complete marker set. We discuss the features of the ancient Eurasian population structure and strategies to identify aAIMs. This work informs the design of single nucleotide polymorphism (SNP) microarrays and the interpretation of aDNA results, which enables a population-wide testing of primordialist theories.

Identification of Marbling Gene Loci in Commercial Pigs in Canadian Herds

We examined the amount of marbling and tested the genome of boars from 5 breeds of Duroc, Iberian, Lacombe, Berkshire and Pietrian that were commercially available for a swine herd in Canada. The marbling was ranked according to the amount of intramuscular fat % obtained in loin chops consisting of the longissimus dorsi muscle. The genetics were analysed by genome wide association study using 80,000 single nuclear polymorphism (SNP) microarrays. Our samples had pork that achieved > 7 % IMF from 110kg animals. Meta-analysis revealed SNP markers that were associated with the highest marbled pork chops on chromosomes 5, 7, and 16. Using the susScr 11.1 map, we determined that the nearest genes were SSNP, Rh glycoprotein and EGFLAM. We tested a sub-population of Duroc sired animals and found a different set of markers close to GRLB and KCNJ3 on chromosomes 8 and 15. Based on our sample, we can achieve pork with good marbling from animals conventionally raised to standard market weights of 110kg. The choice of a good marbling line of pig is not necessarily breed specific.