SHH and Bardet-Biedl syndrome: Previous studies implicated Shh in the aetiology of Bardet-Biedl syndrome, characterised by facial dysmorphology due to aberrant NCC homing and localisation [51] and using both in vitro cell culture and in vivo models, recent work has shown that mesencephalic NCC migrate to the ocular region as a chemotactic response to an exogenous concentration gradient of the Shh morphogen [52].