Homozygous PCDH12 variants result in phenotype of cerebellar ataxia, dystonia, retinopathy, and dysmorphism.

We report on a sib pair of Indian origin born of a consanguineous parentage with a novel phenotype of distinct facial dysmorphism, cerebellar ataxia, dystonia, and exudative retinopathy due to homozygous PCDH12 nonsense variations. cDNA studies showed >90% reduction in transcript levels in both patients, indicating nonsense-mediated decay and loss of function as the probable causative molecular mechanism of the phenotype.