Ocular and Systemic Phenotyping of Bardet-Biedel Syndrome Type 7 (BBS7) in a Palestinian Male: Case Report and...

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy with at least 26 identified causative genes. BBS7 accounts for approximately 1.5% of cases. The syndrome is characterized by retinal degeneration, obesity, polydactyly, intellectual disability, and renal anomalies. BBS7 encodes a core subunit of the BBSome complex, which is essential for ciliary function and intracellular signaling.

We report a 9-year-old Palestinian boy with BBS7, confirmed by whole exome sequencing identifying a homozygous pathogenic variant in the BBS7 gene [c.712_715del]; both parents were heterozygous carriers. To our knowledge, this is the first genetically confirmed case of BBS7 in Palestine. Written informed consent was obtained from the father, the legal guardian. The patient exhibited postaxial polydactyly, generalized obesity (BMI 32.8), developmental delay, learning difficulties, hypothyroidism, and mild craniofacial dysmorphism. Ocular findings included a best-corrected visual acuity of 20/33 bilaterally, compound myopic astigmatism (spherical equivalents: -7.12 D OD and -7.25 D OS), and 15 prism diopters of constant left exotropia. Optical coherence tomography revealed marked thinning of the retinal nerve fiber layer and ganglion cell complex consistent with progressive retinal degeneration. Fundus imaging demonstrated tilted optic discs, bone spicule pigmentation, and peripapillary atrophy. Full-field electroretinography confirmed rod-cone dystrophy with significantly reduced amplitudes and prolonged implicit times. Corneal topography showed no evidence of keratoconus.

This case contributes novel region-specific clinical and genetic data on BBS7, with comprehensive ophthalmic phenotyping including OCT, full-field ERG, and corneal topography. It underscores the value of early multidisciplinary evaluation and genetic testing, particularly in consanguineous populations. Continued reporting of genetically confirmed BBS7 cases will strengthen understanding of genotype-phenotype correlations and support improved clinical management.