SCLT1 was also proposed to be causative of early-onset RP since: i) this gene causes oro-facial-digital syndrome type IX, a very rare and severe ciliopathy with congenital eye defects; ii) patients are heterozygotes for one missense and one splicing altering mutations; and indeed iii) the variants cosegregate with the disease in the family (Fig 1). This evidence concerns the gene SCLT1 and retinitis pigmentosa 1.