FORGE Canada Consortium: outcomes of a 2-year national rare-disease gene-discovery project

Abstract

Inherited monogenic disease has an enormous impact on the well-being of children and their families. Over half of the children living with one of these conditions are without a molecular diagnosis because of the rarity of the disease, the marked clinical heterogeneity, and the reality that there are thousands of rare diseases for which causative mutations have yet to be identified. It is in this context that in 2010 a Canadian consortium was formed to rapidly identify mutations causing a wide spectrum of pediatric-onset rare diseases by using whole-exome sequencing. The FORGE (Finding of Rare Disease Genes) Canada Consortium brought together clinicians and scientists from 21 genetics centers and three science and technology innovation centers from across Canada. From nation-wide requests for proposals, 264 disorders were selected for study from the 371 submitted; disease-causing variants (including in 67 genes not previously associated with human disease; 41 of these have been genetically or functionally validated, and 26 are currently under study) were identified for 146 disorders over a 2-year period. Here, we present our experience with four strategies employed for gene discovery and discuss FORGE's impact in a number of realms, from clinical diagnostics to the broadening of the phenotypic spectrum of many diseases to the biological insight gained into both disease states and normal human development. Lastly, on the basis of this experience, we discuss the way forward for rare-disease genetic discovery both in Canada and internationally.

Figure 1

A Map of Canada Depicts the Location of Participating Clinical Sites and S&T ICs Abbreviations are as follows: GQ, Genome Quebec; and S&T ICs, science and technology innovation centers.

Figure 2

Outcomes of the 264 Disorders Studied with Each Strategy Strategy 1 was used for multiple unrelated individuals or families affected by the same very rare but highly recognizable clinical condition (32 disorders); strategy 2a was for consanguineous families (60 disorders); strategy 2b was for autosomal-dominant families (19 disorders); strategy 3 was for nonconsanguineous families with two or more affected siblings (62 disorders); and strategy 4 was for single affected individuals with no family history (91 disorders).