Bardet-Biedl Syndrome in India: Genotypic Spectrum and Clinical Features From a Single-Centre Cohort.

This study looked at the genetic causes and symptoms of Bardet-Biedl Syndrome (BBS) in 15 patients from India. The researchers used advanced genetic testing to identify which specific genes were damaged in each patient, then compared the symptoms to see if certain gene problems caused more severe illness. They found that the genes most commonly affected in Indian patients were BBS10 and BBS2, which is different from what's typically seen in other parts of the world where BBS1 is usually the main culprit. The study revealed some important patterns about how the disease affects people. All patients had obesity, and nearly 90% had vision problems (retinal dystrophy) and extra fingers or toes (polydactyly). Kidney problems were less common, affecting only about 22% of patients. The researchers found that patients with more severe genetic mutations (called "truncating" mutations) tended to be diagnosed earlier - around age 14 compared to age 28 for those with milder mutations. Patients with BBS10 gene problems seemed to have earlier onset and more body systems affected. This research is important because it shows that BBS affects different populations in different ways, which could help doctors in India diagnose the condition earlier and provide better care. The study suggests that genetic testing could be particularly valuable for families where parents are related (consanguineous families), as this increases the chance of having children with BBS. While this study doesn't offer new treatments, understanding these genetic patterns could help families plan better and ensure earlier diagnosis and care.

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy with multisystem involvement. While BBS1 mutations are common globally, population-specific genetic patterns and phenotype severity vary. This study aimed to investigate genotype-phenotype correlations in an Indian cohort. In this single-centre, observational cohort study, individuals meeting Beales' clinical criteria for BBS underwent next-generation sequencing (NGS). Phenotypic features were correlated with underlying genotypes, with particular attention to the type of mutation (truncating vs. non-truncating) and the implicated gene subgroup (chaperonin-like vs. BBSome complex). Of 15 patients screened, nine were confirmed to have BBS. The most frequently mutated genes were BBS10 and BBS2 (33.3% each), followed by BBS9 and BBS12. All variants were homozygous, with truncating mutations observed in 77.8% of cases. Obesity was universally present, while retinal dystrophy and polydactyly were each seen in 88.9% of patients. Renal abnormalities were less frequent (22.2%) and were observed only among patients with truncating variants in this cohort. Compared with non-truncating mutations, truncating variants were associated with earlier diagnosis (median age: 14 vs. 28.5 years), possibly reflecting earlier clinical manifestations. Notably, earlier onset of disease and broader multisystem involvement were more frequently observed in patients with BBS10 mutations. This study provides descriptive insights into the genotypic spectrum of BBS in an Indian cohort, with frequent involvement of BBS10 and BBS2. The findings underscore the importance of population-specific genetic data and highlight the potential value of early genetic evaluation in consanguineous families.