ABCA4 and Stargardt disease: Craniofacial enhancers have been identified within the introns of ABCA4 (ref. 23), but ABCA4 gene is not a good candidate for the risk gene because, first, in mice, expression of Abca4 is not detectable in the developing lip or palate3; second, in mice homozygous for targeted loss-of-function mutations in Abca4, no defects in craniofacial structure were reported24; and, finally, in humans, coding mutations in ABCA4 that cause profound defects in retinal function (that is, Stargardt's disease 1 (refs 25, 26, 27)) do not appear to cause CL/P.