Clinical evidence of decreased olfaction in Bardet-Biedl syndrome caused by a deletion in the BBS4 gene

Recent discoveries have lead to the hypothesis that ciliary dysfunction is a mechanism underlying the pathogenesis of Bardet-Biedl syndrome (BBS). Here, we describe two individuals with decreased olfaction who are members of an extended family affected with BBS caused by a homozygous deletion (c.77-220del) in the BBS4 gene. These findings correlate with the evidence that several BBS proteins, including BBS4, are expressed in the olfactory epithelium (OE). Although the prevalence and the spectrum of impaired olfaction in BBS are not known, the causal relationship of the BBS4 deletion in this family and the decreased olfaction is corroborated by evidence that Bbs2 and Bbs4 knockout mice have severe olfaction deficits and that also patients with BBS caused by mutations in other BBS genes can have impaired olfaction. This finding broadens the spectrum of clinical manifestations associated with BBS, confirms the role of BBS4 in olfaction, and lends support to the hypothesis that ciliary dysfunction is an important aspect of BBS pathogenesis. © 2005 Wiley-Liss, Inc

Allelic variation in the VMD2 gene in best disease and age-related macular degeneration.

PURPOSE: To assess the allelic variation of the VMD2 gene in patients with Best disease and age-related macular degeneration (AMD). METHODS: Three hundred twenty-one AMD patients, 192 ethnically similar control subjects, 39 unrelated probands with familial Best disease, and 57 unrelated probands with the ophthalmoscopic findings of Best disease but no family history were screened for sequence variations in the VMD2 gene by single-strand conformation polymorphism (SSCP) analysis. Amplimers showing a bandshift were reamplified and sequenced bidirectionally. In addition, the coding regions of the VMD2 gene were completely sequenced in six probands with familial Best disease who showed no SSCP shift. RESULTS: Forty different probable or possible disease-causing mutations were found in one or more Best disease or AMD patients. Twenty-nine of these variations are novel. Of the 39 probands with familial Best disease, mutations were detected in all 39 (33 by SSCP and 6 by DNA sequencing). SSCP screening of the 57 probands with a clinical diagnosis of Best disease but no family history revealed 16 with mutations. Mutations were found in 5 of 321 AMD patients (1.5%), a fraction that was not significantly greater than in control individuals (0/192, 0%). CONCLUSIONS: Patients with the clinical diagnosis of Best disease are significantly more likely to have a mutation in the VMD2 gene if they also have a positive family history. These findings suggest that a small fraction of patients with the clinical diagnosis of AMD may actually have a late-onset variant of Best disease, whereas at the same time, a considerable fraction of isolated patients with the ophthalmoscopic features of Best disease are probably affected with some other macular disease