A novel splice variant in EMC1 is associated with cerebellar atrophy, visual impairment, psychomotor retardation with epilepsy

Background Several genes have been implicated in a highly variable presentation of developmental delay with psychomotor retardation. Mutations in EMC 1 gene have recently been reported. Herein, we describe a proband born of a consanguineous marriage, who presented with early infantile onset epilepsy, scaphocephaly, developmental delay, central hypotonia, muscle wasting, and severe cerebellar and brainstem atrophy. Methods Genetic testing in the proband was performed using custom clinical exome and targeted next‐generation sequencing. This was followed by segregation analysis of the variant in the parents by Sanger sequencing and evaluation of the splice variant by RNA sequencing. Results Clinical exome sequencing identified a novel homozygous intronic splice variant in the EMC 1 gene (chr1:19564510C>T, c.1212 + 1G>A, NM _015047.2). Neither population databases (Ex AC and 1000 genomes) nor our internal database ( n  = 1,500) had reported this rare variant, predicted to affect the splicing. RNA sequencing data from the proband confirmed aberrant splicing with intron 11 retention, thereby introducing a stop codon in the resultant mRNA . This nonsense mutation is predicted to result in the premature termination of protein synthesis leading to loss of function of the EMC 1 protein. Conclusion We report, for the first time the role of aberrant EMC 1 RNA splicing as a potential cause of disease pathogenesis. The severe epilepsy observed in our study expands the disease‐associated phenotype and also emphasizes the need for comprehensive screening of intronic splice mutations.