RASSF1 and achondroplasia: Although it may be desirable to multiplex the fetal target sequence and RASSF1A, using two differentially labelled hydrolysis probes, having a single SYBR Green RASSF1A assay means that this can be used in an economic manner in conjunction with other single gene tests e.g. rhesus D testing, achondroplasia without the need for extensive re-optimisation and validation of PCR multiplexes in a diagnostic setting.