Related Experiment Video
Updated: Oct 23, 2025

Merging Absolute and Relative Quantitative PCR Data to Quantify STAT3 Splice Variant Transcripts
Published on: October 9, 2016
A rare canonical splice-site variant in VPS13B causes attenuated Cohen syndrome
Malena Daich Varela1,2, Fabiana Louise Motta1,3, Andrew R Webster1,2
1UCL Institute of Ophthalmology, London, UK.
Background:
To describe a patient with a history of obesity, retinal dystrophy, type II diabetes, and mild cognitive impairment; found to harbour biallelic splice-site variants in VPS13B.
Materials & Methods:
A complete ophthalmic evaluation was performed at Moorfields Eye Hospital (London, United Kingdom), consisting of measurement of best-corrected visual acuity (BCVA), slit lamp and dilated fundus evaluation, colour, autofluorescence and near-infrared retinal imaging, spectral domain-optical coherence tomography, and electroretinogram (ERG). Whole-genome sequencing was performed as part of the UK's 100,000 Genomes Project.
Results:
A 26-year-old Pakistani man with normal appearance, stature, and head size presented with decreased BCVA and severely constricted visual fields to our Ophthalmic Genetics clinic. He had a history of obesity, type II diabetes, and mild cognitive impairment. His evaluation showed retina-wide, severe photoreceptor dysfunction in both eyes, with undetectable scotopic and photopic ERG waveforms. Genomic analysis identified a homozygous rare splice donor variant in the VPS13B gene (c.5024+2T>C) that was demonstrated to lead to skipping of the in-frame exon 31 (p.Gln1607_Ser1675delinsHis).
Conclusions:
Exon 31 skipping in VPS13B may lead to a hypomorphic change, with partial gene function and an incomplete, mild Cohen syndrome-like phenotype.
Related Concept Videos
Comparing Copy Number Variations and SNPs
Copy number variations or CNVs are the structural variations that cover more than 1kb of DNA sequence. The single nucleotide polymorphism (SNP), on the other hand, is a single nucleotide change or a point mutation that is found in more than 1%...
Single Nucleotide Polymorphisms-SNPs
Alternative RNA Splicing
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...
RNA Splicing
Point and Frameshift Mutations
Pleiotropy

