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statistical tools in genetics

forest) are being sequenced and high volume sequencing methods are advancing; with suitable phenotyping to match, association mapping will follow. One high-value cash crop tree, the cocoa tree (Teobroma cacao), has already[12]

received close AM attention: almost

250 samples, from 17 countries in Latin and South American or the Caribbean, yielding close to 150,000 expressed sequence tags and a high-density genetic map. Looking to the future, the ways in which

researchers analytically interact with data seem set to change in wide ranging ways. Current corporate providers of solutions are, as in every other area of computing, being joined by open systems and imaginative uses of distributed access. Te Discovery Environment provided by iPlant Collaborative (a non-profit virtual organisation, funded by the US National Science Foundation, centred at the University of Arizona, and now in its third year), to take just one example, provides a web portal through which botanists and other plant scientists can both provide and access analytic tools. Tose tools sit on high-performance computing platforms, will handle terabyte scale data sets and can be used by anyone through a semi- friendly graphical user interface. Data can be stored, analyses run, results shared. Looking at the ways in which distributed

Top and centre: distribution of over 7,000 Arabidopsis accessions, Bottom left: Comparison of expected and observed occurrences of 8,133 independent premature stops in 4,263 protein coding genes (from Weigel[10]

; data from Cao[11] et al, maps by George Wang)

an application of linkage disequilibrium (LD) mapping techniques, has a solid history in study of disease in humans. In this connection, as one approach to formalised study of genetic disease architectures, probabilistic graphical models (already well established in bioinformatic gene expression and linkage analyses) are appearing in support of AM methods up to genome scale, although there are limitations in that respect. AM has tended to emphasise high-frequency alleles, but development of statistical models is addressing this and some interesting plant studies exploit them. Brassicæ once again raise their leafy little heads[10, 11]

here and not

without reason. Tough statistically powerful and capable of very high mapping resolution, AM is dependent upon well-established understanding of single nucleotide polymorphisms (SNPs) within the organism being studied. It can, therefore, be most effectively applied to those subjects whose genomes are already known


and, conversely, is least useful in those not yet recorded in sufficient detail. Tat limitation is, of course, fluid and

progressively under revision as new genomes are explored, mapped and published. An increasing number of trees (both orchard and

Further information BGI Broad Institute

The Cancer Genome Atlas (TCGA)

Complete Genomics www.completegenomics. com



iPlant Collaborative

Life Technologies


Systat Software

Thermo Fisher Scientific

VSN International

Wolfram Research

and/or cloud-based computing structures are spreading and establishing themselves, it seems likely that this model or something like it is the pattern to expect. How exactly it will interact and cohabit with present corporate providers is anyone’s guess, but that’s not a question peculiar to genetics. Some companies have already moved experimentally down the ‘free up to a point’ route opened up by small shareware and similar vendors: Wolfram Research, for example, has for some years provided several web-based access points through which anyone with a web browser can make use of Mathematica facilities on a small scale basis, thereby setting out its stall for those who need more and are willing to pay for it. Statistical soſtware publishers, like office suite publishers, get support from customers who do not want to rely on the excellent but unsupported free alternatives. Perhaps genetic analysis will support the same kind of mixed market. Whatever the mechanisms, they will for the foreseeable future be following an ever-upward spiral of size, speed and complexity.

References and Sources For a full list of references and sources, visit features/referencesjun12.php

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