Ocular Characteristics of Patients With Bardet–Biedl Syndrome Caused by Pathogenic BBS Gene Variation in a Chinese Cohort

Abstract

Bardet–Biedl syndrome (BBS; OMIM 209900) is a rare genetic disease causing damage to multiple organs and affecting patients’ quality of life in late adolescence or early adulthood. In this study, the ocular characteristics including morphology and function, were analyzed in 12 BBS patients from 10 Chinese families by molecular diagnostics. A total of five known and twelve novel variants in four BBS genes (BBS2, 58.33%; BBS4, 8.33%; BBS7, 16.67%; and BBS9, 16.67%) were identified in 10 Chinese families with BBS. All patients had typical phenotypes of retinitis pigmentosa with unrecordable or severely damaged cone and rod responses on full-field flash electroretinography (ffERG). Most of the patients showed unremarkable reactions in pattern visual evoked potential (PVEP) and multifocal electroretinography (mfERG), while their flash visual evoked potentials (FVEP) indicated display residual visual function. Changes in the fundus morphology, including color fundus photography and autofluorescence (AF) imaging, were heterogeneous and not consistent with the patients’ functional tests. Overall, our study expands the variation spectrum of the BBS gene, showing that the ocular characteristics of BBS patients are clinically highly heterogeneous, and demonstrates the usefulness of a combination of the ffERG and FVEP assessments of visual function in the advanced stage of retinopathy in BBS.

Ophthalmic and Genetic Features of Bardet Biedl Syndrome in a German Cohort

“…The visual acuity of the BBS cohort decreased from an average of around 0.2 in young children to 0 at age 50 ( Figure 1 ). This is comparable to that reported elsewhere [ 14 , 36 , 37 , 38 , 39 ]. All of the patients showed changes in the morphology of the fundus in the fundus photographs and AF images, demonstrating that retinal dystrophy is a general deficiency in BBS patients [ 14 , 36 , 37 , 38 , 39 ].…”

“…This is comparable to that reported elsewhere [ 14 , 36 , 37 , 38 , 39 ]. All of the patients showed changes in the morphology of the fundus in the fundus photographs and AF images, demonstrating that retinal dystrophy is a general deficiency in BBS patients [ 14 , 36 , 37 , 38 , 39 ]. RP along with “general imperfections of development” were the first features to be reported about the syndrome [ 3 ].…”

“…We find that the phenotype of the different BBS genes in our cohort is heterogeneous, with diverse features occurring in all mutations. This is characteristic of the syndrome [ 6 , 38 , 67 ]; however, in recent years, by analyzing larger patient cohorts, some associations have been published.…”

Ocular Characteristics of Patients with Leber Congenital Amaurosis 6 Caused by Pathogenic RPGRIP1 Gene Variation in a Chinese Cohort

“…Genomic DNA extraction, targeted next-generation sequencing, and bioinformatics analysis were followed by the methods of Dr. Meng et al 2021 [ 10 ]. Targeted next-generation sequencing (NGS) was performed using a capture panel including 195 known inherited retinal disease (IRD) genes (Supplementary Table 1 ).…”

Two novel variants in a Bardet‐Biedl syndrome type 5 patient with severe renal phenotype

“…More than 20 genes have been found to be associated with BBS. Nearly 40 Chinese families with genetic diagnosis of BBS have been reported, including BBS1, BBS2, BBS3, BBS4, BBS6, BBS7, BBS9, BBS10, BBS12, BBS13 and BBS16 1 . However, BBS5 has never been reported in this population.…”