In case of microdeletion syndromes, it must be emphasized that the PPV of cff-DNA is still quite low, with a large dataset showing only a 13% overall PPV for the most common microdeletion syndromes, such as for Di George syndrome, Prader-Willi/Angelman syndrome, Cri-du-chat syndrome and del1p36 syndrome, depending also, as abovementioned, on the very low prevalence of these conditions [102]. The gene discussed is HCFC1; the disease is Cri-du-chat syndrome.