A somatic activating NRAS variant associated with kaposiform lymphangiomatosis
Genetics in Medicine, 2019•nature.com
Purpose Kaposiform lymphangiomatosis (KLA) is a rare, frequently aggressive, systemic
disorder of the lymphatic vasculature, occurring primarily in children. Even with multimodal
treatments, KLA has a poor prognosis and high mortality rate secondary to coagulopathy,
effusions, and systemic involvement. We hypothesized that, as has recently been found for
other vascular anomalies, KLA may be caused by somatic mosaic variants affecting vascular
development. Methods We performed exome sequencing of tumor samples from five …
disorder of the lymphatic vasculature, occurring primarily in children. Even with multimodal
treatments, KLA has a poor prognosis and high mortality rate secondary to coagulopathy,
effusions, and systemic involvement. We hypothesized that, as has recently been found for
other vascular anomalies, KLA may be caused by somatic mosaic variants affecting vascular
development. Methods We performed exome sequencing of tumor samples from five …
Purpose
Kaposiform lymphangiomatosis (KLA) is a rare, frequently aggressive, systemic disorder of the lymphatic vasculature, occurring primarily in children. Even with multimodal treatments, KLA has a poor prognosis and high mortality rate secondary to coagulopathy, effusions, and systemic involvement. We hypothesized that, as has recently been found for other vascular anomalies, KLA may be caused by somatic mosaic variants affecting vascular development.
Methods
We performed exome sequencing of tumor samples from five individuals with KLA, along with samples from uninvolved control tissue in three of the five. We used digital polymerase chain reaction (dPCR) to validate the exome findings and to screen KLA samples from six other individuals.
Results
We identified a somatic activating NRAS variant (c.182 A>G, p.Q61R) in lesional tissue from 10/11 individuals, at levels ranging from 1% to 28%, that was absent from the tested control tissues.
Conclusion
The activating NRAS p.Q61R variant is a known “hotspot” variant, frequently identified in several types of human cancer, especially melanoma. KLA, therefore, joins a growing group of vascular malformations and tumors caused by somatic activating variants in the RAS/PI3K/mTOR signaling pathways. This discovery will expand treatment options for these high-risk patients as there is potential for use of targeted RAS pathway inhibitors.
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