Genomic landscape of Juvenile Myelomonocytic Leukemia (JMML) - A real
world context
Abstract
Background: JMML is a pediatric haematopoietic stem cell malignancy
characterised by uncontrolled proliferation of myelomonocytic and
progenitor compartments and a poor outcome. We comprehensively evaluated
the genomic profile of JMML that presented to our hospital for diagnosis
and treatment. Procedure: We developed a 51-gene (151.5kB) low-cost
targeted myeloid panel based on single-molecule molecular inversion
probes. A total of 50 children with clinical and pathological features
of JMML were sequenced at high coverage on an Illumina MiSeq. The
presenting clinical, laboratory and follow-up data were procured from
the electronic medical record system of the institution. Results: The
median age of our cohort was 2 years, with a male preponderance. Among
the 50 patients, 43 (86%)harboured mutations in one of the
RAS/MAPK-pathway genes, most frequently in PTPN11 (14, 28%), and NRAS
(14, 28%), followed by NF1(11. 22%). Interestingly, 20% (10) of
children had more than one mutation, with 5 cases harbouring two
RAS-pathway mutations. Monosomy 7 was detected in 32% (16) patients,
and five of these did not harbour any RAS-pathway mutations. The
follow-up data revealed that 37 (74%) of these children had succumbed
to the disease. Children with monosomy 7 showed shorter overall
survival, compared to their wildtype counterparts (p=0.02). Conclusion:
Our study highlights that comprehensive genomic profiling identifies at
least one mutation in almost 90% of JMML patients. Performing genomic
analysis early in evaluation of JMML might help in triaging patients for
allogenic stem cell transplant in resource-constrained settings.