Comprehensive clinical and genetic characterization of Bardet-Biedl Syndrome: insights from the largest Turkish cohort.

This study looked at 25 people with Bardet-Biedl Syndrome (BBS) in Turkey - the largest group of confirmed BBS patients studied in that country. The researchers used genetic testing to examine the DNA of these patients and found that all of them had harmful changes (mutations) in genes that cause BBS. They discovered three new genetic mutations that hadn't been seen before. The study found that vision problems were the most common symptom, affecting 94% of patients, followed by extra fingers or toes (88%), obesity (68%), and kidney problems (52%). Interestingly, even people with the same genetic mutations showed different symptoms - some had more severe problems while others had milder ones. This shows that BBS can vary quite a bit from person to person, even within families. This research is important because it helps doctors better understand how BBS appears in different populations, especially in countries like Turkey where marriages between relatives are more common (which can make genetic conditions more likely to occur). The findings support using comprehensive genetic testing panels to diagnose BBS and could help create better care plans and patient registries for people with this rare condition.

Bardet-Biedl Syndrome (BBS) is a rare, pleiotropic ciliopathy involving retinal dystrophy, polydactyly, obesity, and renal abnormalities. Despite growing knowledge of its genetic basis, data from populations with high rates of consanguinity remain limited. This study presents the largest genetically confirmed BBS cohort reported from Türkiye, consisting of 25 individuals who underwent clinical exome-based multigene panel testing. Biallelic pathogenic variants were identified in all patients, including three novel variants in the ARL6/BBS3, BBS9, and BBS10 genes, observed in four patients, including two siblings. Retinal dystrophy was the most common feature (94.1%), followed by polydactyly (88.0%), obesity (68.0%), and renal anomalies (52.0%). Genotype-phenotype comparisons highlighted notable variability, particularly among individuals with BBS1 and BBS10 pathogenic variants, consistent with prior international cohorts. This cohort underscores the clinical heterogeneity of BBS and reveals potential population-specific patterns shaped by consanguinity and genetic background. Our findings support the utility of multigene panels in clinical diagnosis and provide a basis for national registries and targeted care strategies for rare inherited diseases in underrepresented populations.