A Review of the Ocular Phenotype and Correlation with Genotype in Poretti-Boltshauser Syndrome.

: Poretti-Boltshauser syndrome (PBS) is a rare, autosomal recessive disorder caused by pathogenic variants in the gene, resulting in laminin dysfunction. This manifests as a cerebellar malformation with cysts, and patients present with developmental delay and ataxia; however, ocular features are not well-characterised. We aimed to summarise the ocular phenotypes of PBS based on cases reported in the literature. : A literature search was conducted on Medline, Embase, and PubMed on PBS and its ocular associations. Genetically confirmed PBS cases were reviewed, and genotype-phenotype correlations were investigated. : Comprehensive reporting of genotypes and associated systemic and ocular phenotypes was available in 51 patients with PBS, who had 52 distinct variants in . Most patients carried homozygous variants. The most common genotype was a c.2935delA homozygous mutation, followed by the c.768+1G>A; c.6701delC compound heterozygous mutation. High myopia was the most common ocular phenotype ( = 39), followed by strabismus ( = 27) and ocular motor apraxia ( = 26). A wide range of other ocular manifestations, including retinal dystrophy, retinal neovascularisation, retinal detachment, strabismus, nystagmus, optic disc and iris hypoplasia, were reported. Patients with the same genotype exhibited variable expressivity. : PBS has a broad ocular phenotypic spectrum, and characterisation of this variability is important for making an accurate diagnosis and informing genetic counselling.