Although previously classified as likely benign, we observed this in trans with a probable LOF variant in all cases, which may indicate that the variant may be mild and only pathogenic when in trans with a null allele, similar to the situation in ABCA4-retinopathy where the common c.5603 A > T p.(Asn1868Ile) variant is only thought to result in disease in trans with a severe counter-allele20. This evidence concerns the gene ABCA4 and retinal disorder.