We present the case of a patient affected with Williams syndrome (WS), who developed a suspected malignant hyperthermia (MH) reaction to general anesthesia. The proximity to the WS region of the gene encoding the L-type voltage-gated calcium channel alpha 2/delta-subunit (CACNL2A) on 7q11.23-q21.1, previously shown to be closely linked to some forms of MH susceptibility, prompted us to investigate whether this gene is deleted in WS. Linkage studies and fluorescence in situ hybridization analysis demonstrated that the CACNL2A locus is localized outside the WS deleted region.