To investigate whether the developmental defects characteristic of SLOS patients are associated with an aberrant response to SHH, we derived MEFs from a transgenic mouse model of SLOS in which the Dhcr7 gene had been engineered to mimic the prevalent c.964-1G>C allele that codes for a C-terminal truncated protein devoid of enzymatic activity (79). This evidence concerns the gene SHH and Smith-Lemli-Opitz syndrome.