技术资料

Developmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders,resulting in early-onset,therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy,severe developmental delay,progressive microcephaly,visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent,homozygous variant (chr2:64083454A {\textgreater} G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform,which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells,leading to altered glycogen metabolism,upregulated unfolded protein response and premature neuronal differentiation,as modeled during pluripotent stem cell differentiation in vitro. In contrast,the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly,it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease,even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies. View Publication

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmia syndrome characterized by adrenaline induced ventricular tachycardia. The primary genetic aetiologies underlying CPVT are either autosomal dominant or autosomal recessive inheritance,resulting from heterozygous mutations in cardiac ryanodine receptor (RYR2) and homozygous mutations in cardiac calsequestrin-2 (CASQ2),respectively. Recently,a large family with autosomal dominant CPVT due to a heterozygous mutation in CASQ2,p.Lys180Arg,was reported. This resource is the first induced pluripotent stem cell line generated from a patient with autosomal dominant CPVT due to a heterozygous mutation in CASQ2. Induced pluripotent stem cells were generated from the whole blood of a 40-year-old woman with severe CPVT who is heterozygous for the p.Lys180Arg CASQ2 mutation. Induced pluripotent stem cell (iPSC) characterization confirmed expression of pluripotency makers,trilineage differentiation potential,and the absence of exogenous pluripotency vector expression. View Publication

Induced pluripotent stem cells (iPSC) derived from healthy individuals are important controls for disease-modeling studies. Here we apply precision health to create a high-quality resource of control iPSCs. Footprint-free lines were reprogrammed from four volunteers of the Personal Genome Project Canada (PGPC). Multilineage-directed differentiation efficiently produced functional cortical neurons,cardiomyocytes and hepatocytes. Pilot users demonstrated versatility by generating kidney organoids,T lymphocytes,and sensory neurons. A frameshift knockout was introduced into MYBPC3 and these cardiomyocytes exhibited the expected hypertrophic phenotype. Whole-genome sequencing-based annotation of PGPC lines revealed on average 20 coding variants. Importantly,nearly all annotated PGPC and HipSci lines harbored at least one pre-existing or acquired variant with cardiac,neurological,or other disease associations. Overall,PGPC lines were efficiently differentiated by multiple users into cells from six tissues for disease modeling,and variant-preferred healthy control lines were identified for specific disease settings. View Publication