The spectrum of de novo variants in 30,000 individuals with neurodevelopmental disorders

NDD. Trio-exome sequencing is the gold standard to identify the underlying genetic basis in individuals with neurodevelopmental disorders. De novo variants account for the vast majority of causative genetic findings once a diagnosis is made, but the overall genetic landscape is very heterogeneous, with few genes explaining more than 1% of the genetic morbidity. As the largest study of its kind to date, a recent publication in Nature assessed the spectrum of de novo variants in neurodevelopmental disorders in more than 31,000 individuals. The authors identify more than 250 disease-associated genes, highlight 28 novel genetic etiologies, and highlight signals in their data that hint at more than 1,000 disease-associated genes yet to be discovered. In this blog post, I have summarized the five take-home messages from this large study. Continue reading

Pushing the boundary – 27 novel epilepsy genes in the 2017 DDD study

DDD. On January 25, the most recent publication of the Deciphering Developmental Disorders (DDD) study appeared online in Nature. This unprecedented study analyzed the data of 4,293 patient-parent trios with existing data from 3,287 published trios to identify de novo mutations in neurodevelopmental disorders. A study of this size has many aspects that are difficult to fully cover within the limited space of a journal article. Browsing through the data is interesting and will be the foundation for many studies utilizing this data in the near future. Within this first comprehensive blog post of 2017, I try to answer the question what this study means for the field of epilepsy genetics. For example, it provides us with more than 20 epilepsy genes that we did not know about so far. Continue reading

PURA mutations and when diverse phenotypes become a single syndrome

Reverse. With the increasing amount of genetic information available in patients with various neurodevelopmental syndromes, some genes will be observed more than once in patients. In a recent study in the Journal of Medical Genetics, the authors trace back the phenotypes of individuals carrying de novo mutations in PURA. However, there seems to be a wide range of clinical features with a seemingly inverse genotype-phenotype correlation. Continue reading