The present distribution of BBS gene involvement is typical for a population that is mostly of European ancestry. The clinical ocular phenotypes for many of the genotypes not represented in this study (BBS4, BBS6, BBS8, and BBS9) have been described elsewhere in the literature.17,18,21- 23 Generally, these genotypes have shown a severe phenotype, with early blindness and severely reduced or nondetectable ERGs (for studies in which ERG data are provided). No researchers, to our knowledge, have identified a mild ocular phenotype among any of the other genotypes (BBS4, BBS6, BBS8, and BBS9) not included in the present cohort. A severe ocular phenotype has been described by Moore and colleagues21 for the BBS6 genotype, which has a high prevalence in Newfoundland, Canada. Billingsley and colleagues22 likewise found that the phenotype in patients with BBS6 mutations was severe and was similar to that observed in patients with BBS10 and BBS12 mutations, without any statistically significant differences between genotypes. The phenotype of Norwegian patients with BBS4 mutations, described by Riise and colleagues,17 was noted to consist of severe retinitis pigmentosa with onset in early childhood. The BBS2, BBS3, and BBS4 mutations are common in the Bedouin population in the Negev Desert in Israel, and their phenotype was described by Héon and colleagues,23 who noted that retinitis pigmentosa was severe and early in all cases, with moderate to high myopia in BBS4 patients especially. Recently, Deveault and colleagues18 described the clinical ocular phenotypes of a heterogenous population of patients, including some with BBS8 and BBS9 mutations. Patients with mutations in these genes had ERGs that were nondetectable and had very poor acuities. None of the BBS genes not represented in the present study harbored mild ocular phenotypes. Therefore, although we can state definitively only that the BBS1 phenotype is milder than the other genotypes included in this study, it seems that this conclusion also applies to genotypes not included in this cohort because they have all been reported to have severe ocular phenotypes as well.