In this video, Motley Fool health care analyst David Williamson takes a look at three biotech stocks making moves today and what you should know about them. Sequenom (NASDAQ:SQNM) made a big jump today despite higher-than-expected losses because of continued interest in its MaterniT21 Down syndrome test. SciClone Pharmaceuticals (NASDAQ:SCLN) released some disappointing numbers. And ISIS Pharmaceuticals (NASDAQ:IONS) is up 15% after a recent buy rec from Cowen, but Williamson warns that there are some mitigating factors around ISIS that should curb investors' enthusiasm.

David Williamson has no positions in the stocks mentioned above. Follow him on Twitter @MotleyDavid. The Motley Fool owns shares of Illumina. Motley Fool newsletter services recommend Illumina. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.