Single nucleotide polymorphisms (SNPs) are the most frequently occurring genetic variation in the human genome, with the total number of SNPs reported in public SNP databases currently exceeding 9 million. SNPs are important markers in many studies that link sequence variations to phenotypic changes; such studies are expected to advance the understanding of human physiology and elucidate the molecular bases of diseases. For this reason, over the past several years a great deal of effort has been devoted to developing accurate, rapid, and cost-effective technologies for SNP analysis, yielding a large number of distinct approaches. This article presents a review of SNP genotyping techniques and examines their principles of genotype determination in terms of allele differentiation strategies and detection methods. Further, several current biomedical applications of SNP genotyping are discussed.

Morphological studies are reported for a thermotropic liquid crystalline polyester. Small angle light scattering studies were carried out as a function of temperature using Hv and Vv polarization with photographic as well as photometric techniques. No scattering was observed from a thin film cast from a dilute solution of the polymer in a highly volatile solvent. When the film was heated, scattering of light was observed above the glass transition temperature of the polyester. The scattering was found to be azimuthally dependent with Vv intensities being much higher than the corresponding Hv intensities. The size of the morphological features responsible for SALS patterns were calculated and were found not to change significantly with temperature ranging from glass transition temperature to the solid‐nematic transition temperature of the polyester. The WAXS pattern of solution cast polymer was representative of an amorphous structure. Solution cast films heat treated under various conditions (all above the Tg of the polymer) contained crystalline as well as amorphous structures. The maximum apparent crystallinity for annealed samples was of the order of 30%.

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SynopsisT h e morphology of' poly(buty1ene terephthalate) ( P B T ) crystallized from the melt a t various temperatures was studied by small-angle light scattering, polarizing microscopy, and wide-angle x-ray dil'l'raction. Spherulites with a maltese cross a t 4.5' to the polars formed at lower temperatures while spherulites having an apparently higher melting point with a maltese cross along the polars (O0-.1)Oo) I'ormed at higher temperatures. T h e spherulite size and crystallinity increased with increasing crystallization temperature. The H,. scattering patterns arising from the spherulites formed at lower temperature showed intensity maxima at azimuthal angles o f O o and 90", while those ohi itintd at higher temperatures showed the more common 45' intensity maxima. Microtomed samples I'rom molded PBT hars showed spherulites with a 4 5 O maltese cross which changed t o a 0'-90" maltrse cross upon heating just prior to melting. The skin-core effect due to varying thermal histories i t i these molded hars was clearly observed. Solvent crystallized films contained positive O"-90° spherulites. Some changes occurring upon uniaxial stretching of P B T films are also discussed.