Diagnostic Exome Sequencing (DES) coupled with rules-based candidate gene analysis identifies a causative RRAS lesion in a patient with a novel RASopathy.
Family trio DES is an established test that provides a molecular diagnosis in complex cases that are often refractory to diagnosis. Despite this analytical power, many laboratories and/ or institutions employing DES only analyze the approximately 25% of protein coding genes that are strongly associated with clinical disease; they leave the remainder of genes unanalyzed.
Rules-based candidate gene analysis allows for virtually all of the genes in the human exome to be evaluated for their contribution to a patient’s phenotype.
By employing DES with rules-based candidate gene analysis, we determined RRAS p.G39DUP to be the causative lesion in our proband. Not only does this finding recapitulate the work of Flex and colleagues, it expands the phenotypic spectrum associated with RRAS alterations. We propose that RRAS be added to the list of genes that are commonly sequenced in individuals suspected of having a RASopathy.